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Sample records for antireflection coated s-fap

  1. Laser damage initiation and growth of antireflection coated S-FAP crystal surfaces prepared by pitch lap and magnetorheological finishing

    SciTech Connect

    Stolz, C J; Menapace, J A; Schaffers, K I; Bibeau, C; Thomas, M D; Griffin, A J

    2005-10-31

    Antireflection (AR) coatings typically damage at the interface between the substrate and coating. Therefore the substrate finishing technology can have an impact on the laser resistance of the coating. For this study, AR coatings were deposited on Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals that received a final polish by both conventional pitch lap finishing as well as magnetorheological finishing (MRF). SEM images of the damage morphology reveals laser damage originates at scratches and at substrate coating interfacial absorbing defects. Previous damage stability tests on multilayer mirror coatings and bare surfaces revealed damage growth can occur at fluences below the initiation fluence. The results from this study suggest the opposite trend for AR coatings. Investigation of unstable HR and uncoated surface damage morphologies reveals significant radial cracking that is not apparent with AR damage due to AR delamination from the coated surface with few apparent cracks at the damage boundary. Damage stability tests show that coated Yb:S-FAP crystals can operate at 1057 nm at fluences around 20 J/cm{sup 2} at 10 ns; almost twice the initiation damage threshold.

  2. Metasurface optical antireflection coating

    SciTech Connect

    Zhang, Boyang; Hendrickson, Joshua; Nader, Nima; Chen, Hou -Tong; Guo, Junpeng

    2014-12-15

    Light reflection at the boundary of two different media is one of the fundamental phenomena in optics, and reduction of reflection is highly desirable in many optical systems. Traditionally, optical antireflection has been accomplished using single- or multiple-layer dielectric films and graded index surface structures in various wavelength ranges. However, these approaches either impose strict requirements on the refractive index matching and film thickness, or involve complicated fabrication processes and non-planar surfaces that are challenging for device integration. Here, we demonstrate an antireflection coating strategy, both experimentally and numerically, by using metasurfaces with designer optical properties in the mid-wave infrared. Our results show that the metasurface antireflection is capable of eliminating reflection and enhancing transmission over a broad spectral band and a wide incidence angle range. The demonstrated antireflection technique has no requirement on the choice of materials and is scalable to other wavelengths.

  3. Metasurface optical antireflection coating

    DOE PAGESBeta

    Zhang, Boyang; Hendrickson, Joshua; Nader, Nima; Chen, Hou -Tong; Guo, Junpeng

    2014-12-15

    Light reflection at the boundary of two different media is one of the fundamental phenomena in optics, and reduction of reflection is highly desirable in many optical systems. Traditionally, optical antireflection has been accomplished using single- or multiple-layer dielectric films and graded index surface structures in various wavelength ranges. However, these approaches either impose strict requirements on the refractive index matching and film thickness, or involve complicated fabrication processes and non-planar surfaces that are challenging for device integration. Here, we demonstrate an antireflection coating strategy, both experimentally and numerically, by using metasurfaces with designer optical properties in the mid-wave infrared.more » Our results show that the metasurface antireflection is capable of eliminating reflection and enhancing transmission over a broad spectral band and a wide incidence angle range. The demonstrated antireflection technique has no requirement on the choice of materials and is scalable to other wavelengths.« less

  4. Compound semiconductor oxide antireflection coatings

    NASA Astrophysics Data System (ADS)

    Knopp, K. J.; Mirin, R. P.; Bertness, K. A.; Silverman, K. L.; Christensen, D. H.

    2000-05-01

    We report the development of high quality, broad-bandwidth, antireflection (AR) coatings using the low index provided by wet thermally oxidized Al0.98Ga0.02As. We address the design criteria, fabrication, and characterizations of AR coatings composed of surface and buried oxide layers on GaAs. We show, using native-oxide dispersion data, that surface oxide coatings can be designed to offer a nearly zero minimum of reflectance and a reflectance of <1% over bandwidths as large as 500 nm. Surface coatings having a reflectance minimum of 0.4% and a reflectance of <1% over >250 nm have been experimentally demonstrated at a design wavelength of 1 micrometer. Additionally, buried oxide coatings can be designed with an AlxGa1-xAs matching layer of any composition to exactly match the admittance of any substrate with effective index between 2.5 and 3.5. We have demonstrated buried oxide coatings, also designed for 1 micrometer, having a reflectance minimum of 0.4% and a reflectance of <1% over 21 nm. The calculated optical scattering loss from measured roughness data indicates that reflectance minima as low as 10-4 % are ultimately achievable with native-oxide antireflection coatings.

  5. Yb:S-FAP Lasers

    SciTech Connect

    Schaffers, K I

    2004-01-20

    It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass, diode side-pumped amplifier and ELSA in France is implementing Yb:S-FAP in a 985 nm pump for an EDFA, producing 250 mW. Growth of high optical quality crystals of Yb:S-FAP is a challenge due to multiple crystalline defects. However, at this time, a growth process has been developed to produce high quality 3.5 cm diameter Yb:S-FAP crystals and a process is under development for producing 6.5 cm diameter crystals.

  6. Loss/gain-induced ultrathin antireflection coatings

    PubMed Central

    Luo, Jie; Li, Sucheng; Hou, Bo; Lai, Yun

    2016-01-01

    Tradional antireflection coatings composed of dielectric layers usually require the thickness to be larger than quarter wavelength. Here, we demonstrate that materials with permittivity or permeability dominated by imaginary parts, i.e. lossy or gain media, can realize non-resonant antireflection coatings in deep sub-wavelength scale. Interestingly, while the reflected waves are eliminated as in traditional dielectric antireflection coatings, the transmitted waves can be enhanced or reduced, depending on whether gain or lossy media are applied, respectively. We provide a unified theory for the design of such ultrathin antireflection coatings, showing that under different polarizations and incident angles, different types of ultrathin coatings should be applied. Especially, under transverse magnetic polarization, the requirement shows a switch between gain and lossy media at Brewster angle. As a proof of principle, by using conductive films as a special type of lossy antireflection coatings, we experimentally demonstrate the suppression of Fabry-Pérot resonances in a broad frequency range for microwaves. This valuable functionality can be applied to remove undesired resonant effects, such as the frequency-dependent side lobes induced by resonances in dielectric coverings of antennas. Our work provides a guide for the design of ultrathin antireflection coatings as well as their applications in broadband reflectionless devices. PMID:27349750

  7. Loss/gain-induced ultrathin antireflection coatings.

    PubMed

    Luo, Jie; Li, Sucheng; Hou, Bo; Lai, Yun

    2016-01-01

    Tradional antireflection coatings composed of dielectric layers usually require the thickness to be larger than quarter wavelength. Here, we demonstrate that materials with permittivity or permeability dominated by imaginary parts, i.e. lossy or gain media, can realize non-resonant antireflection coatings in deep sub-wavelength scale. Interestingly, while the reflected waves are eliminated as in traditional dielectric antireflection coatings, the transmitted waves can be enhanced or reduced, depending on whether gain or lossy media are applied, respectively. We provide a unified theory for the design of such ultrathin antireflection coatings, showing that under different polarizations and incident angles, different types of ultrathin coatings should be applied. Especially, under transverse magnetic polarization, the requirement shows a switch between gain and lossy media at Brewster angle. As a proof of principle, by using conductive films as a special type of lossy antireflection coatings, we experimentally demonstrate the suppression of Fabry-Pérot resonances in a broad frequency range for microwaves. This valuable functionality can be applied to remove undesired resonant effects, such as the frequency-dependent side lobes induced by resonances in dielectric coverings of antennas. Our work provides a guide for the design of ultrathin antireflection coatings as well as their applications in broadband reflectionless devices. PMID:27349750

  8. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, C.S.; Reed, S.T.

    1988-01-26

    An antireflection film made from reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  9. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, Carol S.; Reed, Scott T.

    1990-01-01

    An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  10. Nanostructural antireflecting coatings: Classification analysis (A review)

    NASA Astrophysics Data System (ADS)

    Baryshnikova, K. V.; Kadochkin, A. S.; Shalin, A. S.

    2015-09-01

    Many modern optical instruments require the use of high-quality antireflecting coatings. Singleand multilayer homogeneous films are mainly used for this purpose. However, an alternative line is rapidly developed at present, which is devoted to the design and use of nanostructural systems for increasing the transparency of different media. Despite the unified principle of operation of these coatings, which is based on the destructive interference of waves in the direction of reflection of light, approaches to their implementation may differ significantly. Different types of nanostructural coatings are considered in detail and classified, their optical properties are compared, and special attention is paid to methods of their manufacture. It is shown that different antireflecting coatings should be used for different purposes, and that coatings that combine properties of several classes often have better antireflecting capabilities.

  11. Broadband antireflection coatings for multifunctional avionic displays

    NASA Astrophysics Data System (ADS)

    Kumari, Neelam; Kumar, Mukesh; Rao, P. K.; Karar, Vinod; Sharma, Amit Lochan

    2015-06-01

    Broadband Multilayer Antireflection (AR) coatings markedly improve the transmission efficiency of any optical component such as lens, prism, beam-splitter, beam combiner or a window. By reducing surface reflections over a wide wavelength range, broadband antireflection coatings improve transmission and enhance contrast which is desired in avionic displays. The broadband antireflection coating consisting of MgF2, ZrO2 and Al2O3 were designed to cover the whole visible spectrum and fabricated on optical grade glass substrate. The optical characterization of these coatings indicates reduction of the reflection to 2.28% as compared to 8.5 % at 545 nm (i.e. design wavelength of most avionic displays) for bare substrate making them useful in optical displays for avionic applications.

  12. Antireflection coating for high index cemented doublets.

    PubMed

    Willey, R R

    1990-11-01

    Uncoated surfaces of high index glasses when cemented to form lens doublets have inferior antireflection properties to doublets of low index glass. This can be overcome by the application of a single layer coating of aluminum oxide prior to cementing. PMID:20577426

  13. Generalized antireflection coatings for complex bulk metamaterials

    NASA Astrophysics Data System (ADS)

    Maas, Ruben; Mann, Sander A.; Sounas, Dimitrios L.; Alù, Andrea; Garnett, Erik C.; Polman, Albert

    2016-05-01

    We present the optimized design of an antireflection coating to efficiently couple an incident plane wave into a metamaterial with a complex field profile. We show that such an antireflection coating must enable spatial engineering of the field profiles at the coating/metamaterial interface to achieve high transmission, and therefore it is required to be inhomogeneous. As a demonstration, we investigate theoretically a waveguide-based negative-index metamaterial, which under normal incidence cannot be excited due to the antisymmetric propagating eigenmode. Through careful engineering of the field profile, lateral position, and thickness of the coating layer, we enhance the transmission under normal incidence from 0 % to 100 % . This principle may generally be applied to overcome low coupling efficiency between incident plane waves and complex mode profiles in metamaterials.

  14. Antireflection coatings for submillimeter silicon lenses

    NASA Astrophysics Data System (ADS)

    Wheeler, Jordan D.; Koopman, Brian; Gallardo, Patricio; Maloney, Philip R.; Brugger, Spencer; Cortes-Medellin, German; Datta, Rahul; Dowell, C. Darren; Glenn, Jason; Golwala, Sunil; McKenney, Chris; McMahon, Jeffery J.; Munson, Charles D.; Niemack, Mike; Parshley, Stephen; Stacey, Gordon

    2014-07-01

    Low-loss lenses are required for submillimeter astronomical applications, such as instrumentation for CCAT, a 25 m diameter telescope to be built at an elevation of 18,400 ft in Chile. Silicon is a leading candidate for dielectric lenses due to its low transmission loss and high index of refraction; however, the latter can lead to large reflection losses. Additionally, large diameter lenses (up to 40 cm), with substantial curvature present a challenge for fabrication of antireflection coatings. Three anti-reflection coatings are considered: a deposited dielectric coating of Parylene C, fine mesh structures cut with a dicing saw, and thin etched silicon layers (fabricated with deep reactive ion etching) for bonding to lenses. Modeling, laboratory measurements, and practicalities of fabrication for the three coatings are presented and compared. Measurements of the Parylene C anti-reflection coating were found to be consistent with previous studies and can be expected to result in a 6% transmission loss for each interface from 0.787 to 0.908 THz. The thin etched silicon layers and fine mesh structure anti-reflection coatings were designed and fabricated on test silicon wafers and found to have reflection losses less than 1% at each interface from 0.787 to 0.908 THz. The thin etched silicon layers are our preferred method because of high transmission efficiency while having an intrinsically faster fabrication time than fine structures cut with dicing saws, though much work remains to adapt the etched approach to curved surfaces and optics < 4" in diameter unlike the diced coatings.

  15. Plasmonic and silicon spherical nanoparticle antireflective coatings

    NASA Astrophysics Data System (ADS)

    Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

    2016-03-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

  16. Plasmonic and silicon spherical nanoparticle antireflective coatings

    PubMed Central

    Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

    2016-01-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

  17. Plasmonic and silicon spherical nanoparticle antireflective coatings.

    PubMed

    Baryshnikova, K V; Petrov, M I; Babicheva, V E; Belov, P A

    2016-01-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

  18. Antireflective Coatings for Glass and Transparent Polymers.

    PubMed

    Buskens, Pascal; Burghoorn, Marieke; Mourad, Maurice Christian Danho; Vroon, Zeger

    2016-07-12

    Antireflective coatings (ARCs) are applied to reduce surface reflections. We review coatings that reduce the reflection of the surface of the transparent substrates float glass, polyethylene terephthalate, poly(methyl methacrylate), and polycarbonate. Three main coating concepts exist to lower the reflection at the interface of a transparent substrate and air: multilayer interference coatings, graded index coatings, and quarter-wave coatings. We introduce and discuss these three concepts, and zoom in on porous quarter-wave coatings comprising colloidal particles. We extensively discuss the four routes for introducing porosity in quarter-wave coatings through the use of colloidal particles, which have the highest potential for application: (1) packing of dense nanospheres, (2) integration of voids through hollow nanospheres, (3) integration of voids through sacrificial particle templates, and (4) packing of nonspherical nanoparticles. Finally, we address the remaining challenges in the field of ARCs, and elaborate on potential strategies for future research in this area. PMID:27187719

  19. Optical enhancing durable anti-reflective coating

    DOEpatents

    Maghsoodi, Sina; Varadarajan, Aravamuthan; Movassat, Meisam

    2016-07-05

    Disclosed herein are polysilsesquioxane based anti-reflective coating (ARC) compositions, methods of preparation, and methods of deposition on a substrate. In embodiments, the polysilsesquioxane of this disclosure is prepared in a two-step process of acid catalyzed hydrolysis of organoalkoxysilane followed by addition of tetralkoxysilane that generates silicone polymers with >40 mol % silanol based on Si-NMR. These high silanol siloxane polymers are stable and have a long shelf-life in the polar organic solvents at room temperature. Also disclosed are low refractive index ARC made from these compositions with and without additives such as porogens, templates, Si--OH condensation catalyst and/or nanofillers. Also disclosed are methods and apparatus for applying coatings to flat substrates including substrate pre-treatment processes, coating processes including flow coating and roll coating, and coating curing processes including skin-curing using hot-air knives. Also disclosed are coating compositions and formulations for highly tunable, durable, highly abrasion-resistant functionalized anti-reflective coatings.

  20. High gain durable anti-reflective coating

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze'ev R.

    2016-07-26

    Disclosed herein are polysilsesquioxane-based anti-reflective coating (ARC) compositions, methods of preparation, and methods of deposition on a substrate. In one embodiment, the polysilsesquioxane of this disclosure is prepared in a two-step process of acid catalyzed hydrolysis of organoalkoxysilane followed by addition of tetralkoxysilane that generates silicone polymers with >40 mol % silanol based on Si-NMR. These high silanol siloxane polymers are stable and have a long shelf-life in polar organic solvents at room temperature. Also disclosed are low refractive index ARC made from these compositions with and without additives such as porogens, templates, thermal radical initiator, photo radical initiators, crosslinkers, Si--OH condensation catalyst and nano-fillers. Also disclosed are methods and apparatus for applying coatings to flat substrates including substrate pre-treatment processes, coating processes and coating curing processes including skin-curing using hot-air knives. Also disclosed are coating compositions and formulations for highly tunable, durable, highly abrasion-resistant functionalized anti-reflective coatings.

  1. Scandium oxide antireflection coatings for superluminescent LEDs

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Zanzucchi, P. J.; Andrews, J. T.; Kane, J.; Depiano, E.

    1986-01-01

    For an employment of laser diodes as superluminescent LEDs (SLDs) or amplifiers, the facets of the diodes must be coated with antireflection films. In the work reported, scandium oxide was evaporated from an e-beam source onto Supersil II fused silica substrates. The obtained samples were used for measurements of absorption and reflectivity. Results of index measurements on e-beam evaporated films are presented. It is shown that excellent coatings with reflectivities of 0.00025 can be obtained using these films. Attention is given to the refractive indices for scandium oxide films as a function of wavelength, the power output vs current for laser before coating and after coating with Sc2O3.

  2. Another Viewpoint On Antireflection Coating Design

    NASA Astrophysics Data System (ADS)

    Willey, Ronald R.

    1990-04-01

    Most antireflection coatings in use today are derived from concepts based on the use of quarter-wave (Q) and half-wave (H) optical thickness layers. We show an alternative and more general way of viewing the concepts and how special cases reduce to the commonly used forms. The monotonically graded inhomogeneous index layer from the substrate to the medium has been extensively reported by Jacobsson and Martensson(1), Dobrowolski and Ho(2), and others. Various oscillating index profiles between the substrate and the medium show promise in producing superior broadband AR coatings. These concepts have evolved from observation of broadband designs using multiple homogeneous quarter- and half-wave optical thickness layers as described by DeBell(3). The viewpoint leads to some further understanding of the possibilities and limitations of AR coatings in general.

  3. Buried nanoantenna arrays: versatile antireflection coating.

    PubMed

    Kabiri, Ali; Girgis, Emad; Capasso, Federico

    2013-01-01

    Reflection is usually a detrimental phenomenon in many applications such as flat-panel-displays, solar cells, photodetectors, infrared sensors, and lenses. Thus far, to control and suppress the reflection from a substrate, numerous techniques including dielectric interference coatings, surface texturing, adiabatic index matching, and scattering from plasmonic nanoparticles have been investigated. A new technique is demonstrated to manage and suppress reflection from lossless and lossy substrates. It provides a wider flexibility in design versus previous methods. Reflection from a surface can be suppressed over a narrowband, wideband, or multiband frequency range. The antireflection can be dependent or independent of the incident wave polarization. Moreover, antireflection at a very wide incidence angle can be attained. The reflection from a substrate is controlled by a buried nanoantenna array, a structure composed of (1) a subwavelength metallic array and (2) a dielectric cover layer referred to as a superstrate. The material properties and thickness of the superstrate and nanoantennas' geometry and periodicity control the phase and intensity of the wave circulating inside the superstrate cavity. A minimum reflectance of 0.02% is achieved in various experiments in the mid-infrared from a silicon substrate. The design can be integrated in straightforward way in optical devices. The proposed structure is a versatile AR coating to optically impedance matches any substrate to free space in selected any narrow and broadband spectral response across the entire visible and infrared spectrum. PMID:24266700

  4. Compatibility of top antireflective coatings and photoresists

    NASA Astrophysics Data System (ADS)

    Li, Ju-Yau; Chuang, Po-Wei; Hsu, Chih-Hsieh F.; Jang, Ben; Chung, Wen-Jye

    1997-08-01

    To improve lithographic process throughput, it has become a general trend to link coater, stepper, and developer to an integrated PHOTO cell. In fine photolithography, TARC (top anti-reflective coating) is utilized intensively to obtain better CD (critical dimension) control. However, the coating of photoresist and TARC is not performed successively. A baking step about 90 seconds is employed in between these two coating steps. Throughput is thus affected and coating step becomes the bottleneck of whole lithography process. A series of experiments were investigated to coat TARC right after photoresist coatings. Results show that throughput was greatly improved. But for certain TARC and photoresist pairs, resist scumming due to inter-mixing of these two chemicals was found after exposure and developing. In some cases, the coater drain piping was stuck by the occurrence of precipitation resulted from the interaction between TARC and photoresist. To prevent this event from happening, precipitation tests of TARC and photoresist are investigated. Experiment was performed by adding TARC to photo resist with/without dilution by thinner. The occurrence of precipitation was observed. Seven kinds of photo resist and three kinds of TARC, provided by different vendors, are studied at different volume ratios on these tests. Results show that the lower photoresist to TARC ratio is, the more precipitation formed. Adding thinner, affecting the precipitation in different ways, induces more precipitation in most cases and cause the precipitation to disappear in some systems. One TARC is found to be inert to most photo resists. Photo resists with higher viscosity turn to gel when interacting with TARC.

  5. A novel approach to antireflection coating using planar metamaterials

    SciTech Connect

    Chen, Hou-tong; Zhou, Jiangfeng; O' Hara, John F; Azad, Abul K; Chen, Frank; Taylor, Antoinette J

    2010-01-01

    We experimentally demonstrate a novel antireflection coating using planar metamaterials. It dramatically reduces the reflectance and enhances the transmittance over a wide range of incidence angles for both polarizations near the designed wavelength.

  6. Advanced Antireflection Coatings for High-Performance Solar Energy Applications

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Phase II objectives: Develop and refine antireflection coatings incorporating lanthanum titanate as an intermediate refractive index material; Investigate wet/dry thermal oxidation of aluminum containing semiconductor compounds as a means of forming a more transparent window layer with equal or better optical properties than its unoxidized form; Develop a fabrication process that allows integration of the oxidized window layer and maintains the necessary electrical properties for contacting the solar cell; Conduct an experimental demonstration of the best candidates for improved antireflection coatings.

  7. High gain durable anti-reflective coating with oblate voids

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze'ev

    2016-06-28

    Disclosed herein are single layer transparent coatings with an anti-reflective property, a hydrophobic property, and that are highly abrasion resistant. The single layer transparent coatings contain a plurality of oblate voids. At least 1% of the oblate voids are open to a surface of the single layer transparent coatings.

  8. Practical anti-reflection coating for metal semiconductor solar cells

    NASA Technical Reports Server (NTRS)

    Yeh, Y.-C. M.; Stirn, R. J.

    1975-01-01

    The metal-semiconductor solar cell is a possible candidate for converting solar to electrical energy for terrestrial application. A method is given for obtaining optical parameters of practical antireflection coatings for the metal-semiconductor solar cell. This method utilizes the measured refractive index obtained from ellipsometry since the surface to be AR coated has a multilayer structure. Both the experimental results and theoretical calculation of optical parameters for Ta2O5 antireflection coatings on Au-GaAs and Au-GaAs(0.78)P(0.22) solar cells are presented for comparison.

  9. Temperature dependence of porous silica antireflective (AR) coating

    NASA Astrophysics Data System (ADS)

    Tang, Yongxing; Le, Yueqin; Zhang, Weiqing; Jiang, Minhua; Sun, Jinren; Liu, Xiaolin

    1998-02-01

    In this paper, the antireflective coatings consisting of porous silica particles from a silica sol are applied by dip method. The relationships among composition, viscosity and temperature have been studied. The coating homogeneity is opium for the laser wavelengths of 1064 nm, 532 nm and 355 nm. The peak transmission of coated BK-7 glass substrate is higher than 99.5%. The laser induced damage thresholds of the antireflective coatings were range of 7 - 10 J/cm2, for 1 ns pulse width and 1064 nm wavelength. These damage thresholds were suitable for our national ICF program. It is noted that the optical homogeneity of coating and the viscosity of coating sol were strongly influenced by the temperatures in the duration of sol ripening.

  10. Measurement of Laser Damage Threshold of 355-nm Antireflection Coating

    NASA Astrophysics Data System (ADS)

    Tamura, Shigeharu; Kimura, Saburo; Sato, Yoshiyuki; Otani, Minoru; Yoshida, Hidetsugu; Yoshida, Kunio

    1989-06-01

    The laser damage thresholds of various types of antireflection (AR) coatings for an UV (355-nm) laser system were measured. Among them, the coatings consisting of two low-index materials, SiO2 and MgF2, had the highest average thresholds: 2.1 J/cm2 on fused silica substrates and 2.6 J/cm2 on sapphire substrates. The SiO2/MgF2 coating is hopeful for UV laser component.

  11. Low-loss antireflection coating for the visible

    NASA Astrophysics Data System (ADS)

    Muscalu, G. L.

    1995-03-01

    It is shown the procedure of achieving a broadband antireflection coating for the visible. The coating structure is composed of 8 layers made of two materials: zirconium dioxide and magnesium fluoride. The experimental efficiency for getting a coating (for the admissibility criterion--specular reflection factor in the spectral (440 - 650) nm coating is achieved under a vacuum system equipped with a photometer that operates at a single wavelength. The coating has the same performances when it is individualized on any type of glass with ne equals 1.48...1.90.

  12. Anti-reflection coatings applied by acid leaching process

    NASA Technical Reports Server (NTRS)

    Pastirik, E.

    1980-01-01

    The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

  13. Anti-reflection coatings applied by acid leaching process

    NASA Astrophysics Data System (ADS)

    Pastirik, E.

    1980-09-01

    The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

  14. Millimeter-wave antireflection coating for cryogenic silicon lenses.

    PubMed

    Lau, Judy; Fowler, Joseph; Marriage, Tobias; Page, Lyman; Leong, Jon; Wishnow, Edward; Henry, Ross; Wollack, Ed; Halpern, Mark; Marsden, Danica; Marsden, Gaelen

    2006-06-01

    We have developed and tested an antireflection (AR) coating method for silicon lenses used at cryogenic temperatures and millimeter wavelengths. Our particular application is a measurement of the cosmic microwave background. The coating consists of machined pieces of Cirlex glued to the silicon. The measured reflection from an AR-coated flat piece is less than 1.5% at the design wavelength. The coating has been applied to flats and lenses and has survived multiple thermal cycles from 300 to 4 K. We present the manufacturing method, the material properties, the tests performed, and estimates of the loss that can be achieved in practical lenses. PMID:16724132

  15. Front surface passivation of silicon solar cells with antireflection coating

    NASA Technical Reports Server (NTRS)

    Crotty, G.; Daud, T.; Kachare, R.

    1987-01-01

    It is demonstrated that the deposition and postdeposition sintering of an antireflection (AR) coating in hydrogen acts to passivate silicon solar cells. Cells with and without an SiO2 passivating layer, coated with a TiO(x)/Al2O3 AR coating, showed comparable enhancements in short-wavelength spectral response and in open-circuit voltage Voc after sintering at 400 C for 5 min in a hydrogen ambient. The improvement in Voc of cells without SiO2 is attributed to front-surface passivation by the AR coating during processing.

  16. Process and performance optimization of bottom antireflective coatings: II

    NASA Astrophysics Data System (ADS)

    Ding, Shuji; Sagan, John P.; Shan, Jianhui; Gonzalez, Eleazar; Dixit, Sunit S.; Liu, Ying; Khanna, Dinesh N.

    1999-06-01

    The newly developed AZ BARLi II coating material is a photoresist solvent-based bottom antireflective coating (BARC) for i-line lithographic application. The coating material has good compatibility with common edge bead removal solvents such as ethyl lactate, PGME, or PGMEA mixed with ethyl lactate or PGME. To evaluate the BARC material, its chemical compatibility with common EBR solvents has been tested by several analytical techniques including liquid particle counts and surface defect studies. Both top and bottom EBR dispense processes have been investigated and optimized. Improvements on edge roughness, visual cleanliness, and the BARC coating buildup at the edge will be discussed in this paper.

  17. Design of broadband omnidirectional antireflection coatings using ant colony algorithm.

    PubMed

    Guo, X; Zhou, H Y; Guo, S; Luan, X X; Cui, W K; Ma, Y F; Shi, L

    2014-06-30

    Optimization method which is based on the ant colony algorithm (ACA) is described to optimize antireflection (AR) coating system with broadband omnidirectional characteristics for silicon solar cells incorporated with the solar spectrum (AM1.5 radiation). It's the first time to use ACA method for optimizing the AR coating system. In this paper, for the wavelength range from 400 nm to 1100 nm, the optimized three-layer AR coating system could provide an average reflectance of 2.98% for incident angles from Raveθ+ to 80° and 6.56% for incident angles from 0° to 90°. PMID:24978076

  18. Visual and energy performance of switchable windows with antireflection coatings

    SciTech Connect

    Jonsson, Andreas; Roos, Arne

    2010-08-15

    The aim of this project was to investigate how the visual appearance and energy performance of switchable or smart windows can be improved by using antireflective coatings. For this study clear float glass, low-e glass and electrochromic glass were treated with antireflection (AR) coatings. Such a coating considerably increases the transmittance of solar radiation in general and the visible transmittance in particular. For switchable glazing based on absorptive electrochromic layers in their dark state it is necessary to use a low-emissivity coating on the inner pane of a double glazed window in order to reject the absorbed heat. In principle all surfaces can be coated with AR coatings, and it was shown that a thin AR coating on the low-e surface neither influences the thermal emissivity nor the U-value of the glazing. The study showed that the use of AR coatings in switchable glazing significantly increases the light transmittance in the transparent state. It is believed that this is important for a high level of user acceptance of such windows. (author)

  19. Bilayer structures optimization as antireflective coating for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Zuccon, S.; Zuppella, P.; Corso, A. J.; Pelizzo, M. G.

    2014-10-01

    The optimization of a silicon solar cell involves also the design of a proper antireflective coating (AR). We have considered different bilayer structures. The use of bilayers is oriented to have an antireflective effect on a broader range of wavelengths compared to single film AR. The materials considered include silicon oxide, magnesium fluoride, silicon nitride and titanium oxide. The thickness of each film in each structure has been optimized by theoretical calculations in order to minimize the weighted reflectivity, Rw. This is calculated taking into account the optical reflectivity, the internal quantum efficiency of the silicon solar cell and the solar flux on all the range of wavelengths of interest. Some of these optimized structures have been realized by e-beam vapor deposition as first tests. The improved optical performance of the samples have been verified at the UV-vis-NIR spectrophotometer.

  20. Development of nanostructured antireflection coatings for EO/IR sensor applications

    NASA Astrophysics Data System (ADS)

    Pethuraja, Gopal G.; Welser, Roger E.; Sood, Ashok K.; Efstathiadis, Harry; Haldar, Pradeep; Wijewarnasuriya, Priyalal S.; Dhar, Nibir K.

    2016-05-01

    Electro-optical/infrared (EO/IR) nanosensors are being developed for a variety of defense and commercial systems applications. One of the critical technologies that will enhance EO/IR sensor performance is the development of advanced antireflection coatings. In this paper, we review our latest work on high quality nanostructure-based antireflection structures, including recent efforts to deposit nanostructured antireflection coatings on IR substrates. Nanostructured antireflection coatings fabricated via oblique angle deposition are shown to enhance the optical transmission through transparent windows by minimizing reflection losses at the spectral band of interest to less than one percent, a substantial improvement over conventional thin-film antireflection coating technologies. Step-graded antireflection structures also exhibit excellent omnidirectional performance, and have recently been demonstrated with good performance in medium wavelength and long wavelength IR spectral bands.

  1. NIF Anti-Reflective Coating Solutions: Preparation, Procedures and Specifications

    SciTech Connect

    Suratwala, T; Carman, L; Thomas, I

    2003-07-01

    The following document contains a detailed description of the preparation procedures for the antireflective coating solutions used for NIF optics. This memo includes preparation procedures for the coating solutions (sections 2.0-4.0), specifications and vendor information of the raw materials used and on all equipment used (section 5.0), and QA specifications (section 6.0) and procedures (section 7.0) to determine quality and repeatability of all the coating solutions. There are different five coating solutions that will be used to coat NIF optics. These solutions are listed below: (1) Colloidal silica (3%) in ethanol (2) Colloidal silica (2%) in sec-butanol (3) Colloidal silica (9%) in sec-butanol (deammoniated) (4) HMDS treated silica (10%) in decane (5) GR650 (3.3%) in ethanol/sec-butanol The names listed above are to be considered the official name for the solution. They will be referred to by these names in the remainder of this document. Table 1 gives a summary of all the optics to be coated including: (1) the surface to be coated; (2) the type of solution to be used; (3) the coating method (meniscus, dip, or spin coating) to be used; (4) the type of coating (broadband, 1?, 2?, 3?) to be made; (5) number of optics to be coated; and (6) the type of post processing required (if any). Table 2 gives a summary of the batch compositions and measured properties of all five of these solutions.

  2. Antireflective coatings applied from metal-organic derived liquid precursors.

    PubMed

    Yoldas, B E; O'Keeffe, T W

    1979-09-15

    Antireflective (AR) coatings, which are produced from organometallic driven solutions containing oxide constituents in a chemically polymerized form, are presented. These solutions leave a film on substrates which, upon heat treatment, converts to a glasslike oxide film having the desired optical thickness and index of refraction. The index can be varied continuously from 1.4 to 2.4; thus the AR coatings can be fine-tuned for different substrates and for specific wavelengths of light. Silicon solar cells AR-coated by this technique showed as much as 49% improvement in efficiency over the uncoated state. The real advantage of the process, however, lies in the fact that it is simple, well-suited for automated mass production of photovoltaic cells, and reduces the cost of coating application from an estimated $0.20 per W-package to about $0.01 per W-package. PMID:20212817

  3. Abrasion-resistant antireflective coating for polycarbonate

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.

    1978-01-01

    Following plasma-polymerization technique, treatment in oxygen glow discharge further enhances abrasion resistance and transmission. Improvement in abrasion resistance was shown by measuring percentage of haze resulting from abrasion. Coating samples were analyzed for abrasion using standard fresh rubber eraser. Other tests included spectra measurements and elemental analysis with spectrometers and spectrophotometers.

  4. Silicon Nitride Antireflection Coatings for Photovoltaic Cells

    NASA Technical Reports Server (NTRS)

    Johnson, C.; Wydeven, T.; Donohoe, K.

    1984-01-01

    Chemical-vapor deposition adapted to yield graded index of refraction. Silicon nitride deposited in layers, refractive index of which decreases with distance away from cell/coating interface. Changing index of refraction allows adjustment of spectral transmittance for wavelengths which cell is most effective at converting light to electric current. Average conversion efficiency of solar cells increased from 8.84 percent to 12.63 percent.

  5. Technical and historical overview of the study at Livermore of porous antireflection coatings

    SciTech Connect

    Milam, D.

    1985-04-04

    The testing program leading to selection of antireflection coatings for the NOVA laser is reviewed. Limiting problems that prevented use of some coating technologies are described, and estimates are made of the current value of pursuing solutions to those problems.

  6. Novel Passivating/Antireflective Coatings for Space Solar Cells

    NASA Technical Reports Server (NTRS)

    Faur, Mircea; Faur, Maria; Bailey, S. G.; Flood, D. J.; Faur, H. M.; Mateescu, C. G.; Alterovitz, S. A.; Scheiman, D.; Jenkins, P. P.; Brinker, D. J.

    2005-01-01

    We are developing a novel process to grow passivating/antireflective (AR) coatings for terrestrial and space solar cells. Our approach involves a Room Temperature Wet Chemical Growth (RTWCG) process, which was pioneered, and is under development at SPECMAT, Inc., under a Reimbursable Space Act Agreement with NASA Glenn Research Center. The RTWCG passivating/AR coatings with graded index of refraction are applied in one easy step on finished (bare) cells. The RTWCG coatings grown on planar, textured and porous Si, as well as on poly-Si, CuInSe2, and III-V substrates, show excellent uniformity irrespective of surface topography, crystal orientation, size and shape. In this paper we present some preliminary results of the RTWCG coatings on Si and III-V substrates that show very good potential for use as a passivation/AR coating for space solar cell applications. Compared to coatings grown using conventional techniques, the RTWCG coatings have the potential to reduce reflection losses and improve current collection near the illuminated surface of space solar cells, while reducing the fabrication costs.

  7. Ultraviolet antireflection coatings for use in silicon detector design

    NASA Astrophysics Data System (ADS)

    Hamden, Erika T.; Greer, Frank; Hoenk, Michael E.; Blacksberg, Jordana; Dickie, Matthew R.; Nikzad, Shouleh; Martin, D. Christopher; Schiminovich, David

    2011-07-01

    We report on the development of coatings for a charged-coupled device (CCD) detector optimized for use in a fixed dispersion UV spectrograph. Because of the rapidly changing index of refraction of Si, single layer broadband antireflection (AR) coatings are not suitable to increase quantum efficiency at all wavelengths of interest. Instead, we describe a creative solution that provides excellent performance over UV wavelengths. We describe progress in the development of a coated CCD detector with theoretical quantum efficiencies (QEs) of greater than 60% at wavelengths from 120 to 300nm. This high efficiency may be reached by coating a backside-illuminated, thinned, delta-doped CCD with a series of thin film AR coatings. The materials tested include MgF2 (optimized for highest performance from 120--150nm), SiO2 (150--180nm), Al2O3 (180--240nm), MgO (200--250nm), and HfO2 (240--300nm). A variety of deposition techniques were tested and a selection of coatings that minimized reflectance on a Si test wafer were applied to functional devices. We also discuss future uses and improvements, including graded and multilayer coatings.

  8. Protective infrared antireflection coating based on sputtered germanium carbide

    NASA Astrophysics Data System (ADS)

    Gibson, Des; Waddell, Ewan; Placido, Frank

    2011-09-01

    This paper describes optical, durablility and environmental performance of a germanium carbide based durable antireflection coating. The coating has been demonstrated on germanium and zinc selenide infra-red material however is applicable to other materials such as zinc sulphide. The material is deposited using a novel reactive closed field magnetron sputtering technique, offering significant advantages over conventional evaporation processes for germanium carbide such as plasma enhanced chemical vapour deposition. The sputtering process is "cold", making it suitable for use on a wide range of substrates. Moreover, the drum format provide more efficient loading for high throughput production. The use of the closed field and unbalanced magnetrons creates a magnetic confinement that extends the electron mean free path leading to high ion current densities. The combination of high current densities with ion energies in the range ~30eV creates optimum thin film growth conditions. As a result the films are dense, spectrally stable, supersmooth and low stress. Films incorporate low hydrogen content resulting in minimal C-H absorption bands within critical infra-red passbands such as 3 to 5um and 8 to 12um. Tuning of germanium carbide (Ge(1-x)Cx) film refractive index from pure germanium (refractive index 4) to pure germanium carbide (refractive index 1.8) will be demonstrated. Use of film grading to achieve single and dual band anti-reflection performance will be shown. Environmental and durability levels are shown to be suitable for use in harsh external environments.

  9. Contamination-resistant silica antireflective coating with closed ordered mesopores.

    PubMed

    Sun, Jinghua; Zhang, Qinghua; Ding, Ruimin; Lv, Haibing; Yan, Hongwei; Yuan, Xiaodong; Xu, Yao

    2014-08-21

    Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability. PMID:25000419

  10. Nanowire-based multifunctional antireflection coatings for solar cells

    NASA Astrophysics Data System (ADS)

    Hiralal, Pritesh; Chien, Chihtao; Lal, Niraj N.; Abeygunasekara, Waranatha; Kumar, Abhishek; Butt, Haider; Zhou, Hang; Unalan, Husnu Emrah; Baumberg, Jeremy J.; Amaratunga, Gehan A. J.

    2014-11-01

    Organic (P3HT/PCBM) solar cells are coated with ZnO nanowires as antireflection coatings and show up to 36% enhancement in efficiency. The improvement is ascribed to an effective refractive index which results in Fabry-Perot absorption bands which match the polymer band-gap. The effect is particularly pronounced at high light incidence angles. Simultaneously, the coating is used as a UV-barrier, demonstrating a 50% reduction in the rate of degradation of the polymers under accelerated lifetime testing. The coating also allows the surface of the solar cell to self-clean via two distinct routes. On one hand, photocatalytic degradation of organic material on ZnO is enhanced by the high surface area of the nanowires and quantified by dye degradation measurements. On the other, the surface of the nanowires can be functionalized to tune the water contact angle from superhydrophilic (16°) to superhydrophobic (152°), resulting in self-cleaning via the Lotus effect. The multifunctional ZnO nanowires are grown by a low cost, low temperature hydrothermal method, compatible with process limitations of organic solar cells.Organic (P3HT/PCBM) solar cells are coated with ZnO nanowires as antireflection coatings and show up to 36% enhancement in efficiency. The improvement is ascribed to an effective refractive index which results in Fabry-Perot absorption bands which match the polymer band-gap. The effect is particularly pronounced at high light incidence angles. Simultaneously, the coating is used as a UV-barrier, demonstrating a 50% reduction in the rate of degradation of the polymers under accelerated lifetime testing. The coating also allows the surface of the solar cell to self-clean via two distinct routes. On one hand, photocatalytic degradation of organic material on ZnO is enhanced by the high surface area of the nanowires and quantified by dye degradation measurements. On the other, the surface of the nanowires can be functionalized to tune the water contact angle

  11. Antireflective graded index silica coating, method for making

    DOEpatents

    Yoldas, Bulent E.; Partlow, Deborah P.

    1985-01-01

    Antireflective silica coating for vitreous material is substantially non-reflecting over a wide band of radiations. This is achieved by providing the coating with a graded degree of porosity which grades the index of refraction between that of air and the vitreous material of the substrate. To prepare the coating, there is first prepared a silicon-alkoxide-based coating solution of particular polymer structure produced by a controlled proportion of water to alkoxide and a controlled concentration of alkoxide to solution, along with a small amount of catalyst. The primary solvent is alcohol and the solution is polymerized and hydrolized under controlled conditions prior to use. The prepared solution is applied as a film to the vitreous substrate and rapidly dried. It is thereafter heated under controlled conditions to volatilize the hydroxyl radicals and organics therefrom and then to produce a suitable pore morphology in the residual porous silica layer. The silica layer is then etched in order to enlarge the pores in a graded fashion, with the largest of the pores remaining being sufficiently small that radiations to be passed through the substrate are not significantly scattered. For use with quartz substrates, extremely durable coatings which display only 0.1% reflectivity have been prepared.

  12. Infrared 8- to 15-μm high-efficiency antireflection coating on germanium substrate

    NASA Astrophysics Data System (ADS)

    Ye, Ke-fei; Su, Zhaoxu; Liu, JiaHuan; Yang, Chongming

    1998-08-01

    To increase the strength of infrared high efficiency antireflection coatings is a problem difficult to be resolved. A mixture of BaF2 and CeF2 has been used as a low refractive index material to design and prepare infrared 8 - 11.5 (mu) high efficiency anti-reflection coating to acquire good strength of film layer. The processing conditions of the films deposition have also been introduced. The spectral transmittance measured, physical and chemical properties of the infrared anti-reflection coating are given.

  13. Nanowire-based multifunctional antireflection coatings for solar cells.

    PubMed

    Hiralal, Pritesh; Chien, Chihtao; Lal, Niraj N; Abeygunasekara, Waranatha; Kumar, Abhishek; Butt, Haider; Zhou, Hang; Unalan, Husnu Emrah; Baumberg, Jeremy J; Amaratunga, Gehan A J

    2014-11-01

    Organic (P3HT/PCBM) solar cells are coated with ZnO nanowires as antireflection coatings and show up to 36% enhancement in efficiency. The improvement is ascribed to an effective refractive index which results in Fabry-Perot absorption bands which match the polymer band-gap. The effect is particularly pronounced at high light incidence angles. Simultaneously, the coating is used as a UV-barrier, demonstrating a 50% reduction in the rate of degradation of the polymers under accelerated lifetime testing. The coating also allows the surface of the solar cell to self-clean via two distinct routes. On one hand, photocatalytic degradation of organic material on ZnO is enhanced by the high surface area of the nanowires and quantified by dye degradation measurements. On the other, the surface of the nanowires can be functionalized to tune the water contact angle from superhydrophilic (16°) to superhydrophobic (152°), resulting in self-cleaning via the Lotus effect. The multifunctional ZnO nanowires are grown by a low cost, low temperature hydrothermal method, compatible with process limitations of organic solar cells. PMID:25350481

  14. Anti-reflection Coatings on Large Area Glass Sheets

    NASA Technical Reports Server (NTRS)

    Pastirik, E.

    1979-01-01

    The first quarter of a one-year program designed to research and perfect a method of producing antireflective coatings on large glass sheets through the use of sodium silicate hardened by exposure to acid is reported. The requirements for a linear motion device used to produce uniform sodium silicate films were determined. A search for a commercially available device is underway. Sodium silicate solutions of varying concentrations were prepared. Determinations of the physical properties relevant to film thickness are in progress. In addition, material costs are being recorded for later use in a cost analysis of the method. All tasks of the project are proceeding according to schedule. Of the tasks, only the sodium silicate solution preparation is complete.

  15. Optimization of multilayer antireflection coating for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Sikder, Urmita; Zaman, Mohammad Asif

    2016-05-01

    Multilayer antireflection coating (ARC) for photovoltaics is optimized using Differential Evolution (DE) algorithm. A general transfer-matrix based mathematical formulation is used for evaluating reflection spectra of the system. Exact and complete values of refractive indices are used in the analysis to provide higher accuracy of the results. The proposed optimization method takes into account the solar irradiance spectra, absorption characteristics of semiconductors and angle of incidence to maximize efficiency. This method is found to reduce the average reflectance for a wide range of angles of incidence. The proposed method is used to design ARC for silicon solar cell and a multi-junction AlGaAs/GaAs/Ge solar cell. Finally, comparative analysis of different ARC designs is provided in terms of corresponding solar cell characteristics.

  16. Modeling Multilayer Antireflection Coating Systems Based on LiNbO3

    NASA Astrophysics Data System (ADS)

    Karaomerlioglu, Filiz

    Antireflection coatings have had the greatest impact on optics. The antireflection (AR) coating is the critically important technology in obtaining high performance of optoelectronic devices. In the present paper, characteristics of the ferroelectric based multilayered antireflection coating systems are investigated. Multilayer antireflection coatings consisting of insulator thin films have been modeled in the region between the 400 nm and 800 nm visible bands of electromagnetic spectrum to reduce reflectance from ferroelectric based substrate. In this type of antireflection coating we can regulate the optical properties of a system by external electric (or thermal field) and design a broadband low reflection coating system for optoelectronic devices. In order to design and simulate the normal incidence wideband visible multilayer AR coatings, we have developed a Fortran software program based upon Fresnell equations. Different types of layers which are two-different materials like ZnSe and ZrO2 for even-folded multilayer (two-, four-, six-, eight-, ten-, and twelve-layer) antireflection coatings are used. Ferroelectric material, LiNbO3 is used as the substrate. The optical thicknesses of each layer are equal to a quarter-wave thick at a certain wavelength.

  17. Challenges of non-PFOS top antireflective coating material

    NASA Astrophysics Data System (ADS)

    Hsu, Shu-Hao; Vermeir, Inge; Scholze, Matthias; Voigt, Matthias; Gierth, Janine; Mittermeier, Armelle; Mäge, Iris; Voelkel, Lars

    2008-03-01

    Top anti-reflective coating (TARC) material is very useful in decreasing standing waves and minimizing swing amplitude of critical dimensions (CD) because it can reduce the reflectivity of structures by interference. TARC can also help to control resist defects, improve CD uniformity, and solve CD variation issues caused by post exposure bake (PEB) delay. The perfluorooctyl sulfonate (PFOS) or perfluorooctanoic acid (PFOA) are used as a surfactant in actual TARC materials. They can reduce surface tension to improve the coating performance of TARC. However, PFOS and PFOA are restricted for future applications due to environmental concerns and should be omitted from TARC materials. Therefore, material vendors start working hard on Non-PFOS TARC material development. In this paper, the PEB delay behavior with and without TARC was discussed. The effect of PEB delay is not only related to the pattern density, but also strongly related to resist material. According to the testing results, there are still some issues in Non-PFOS TARC materials such as coating performance, material removing, defect control, and film loss etc. Taking these Non-PFOS TARC materials as examples, Non-PFOS TARC-3 could not be dissolved completely in alkaline developer. There are serious embedded defects of Non-PFOS TARC-2 on patterned wafer. Additionally, Non-PFOS TARC-1 shows an acceptable defect level without TARC baking, but it has poor edge coating and more film loss issues. The issue of poor film coating could be solved by coating recipe modification and also by improvements on the material itself made by the material vendor. Therefore, Non-PFOS TARC-1 without TARC baking can be a candidate for a Non-PFOS TARC process because of its acceptable Litho performances and defect density.

  18. New protective antireflecting coating for multispectral ZnS

    NASA Astrophysics Data System (ADS)

    Clark, Caspar C.; Lettington, Alan H.; Wakeham, Steven J.; Jones, Peter S.; Waterman, Dave

    2001-09-01

    With the advent of common aperture systems comes a requirement for substrates and coatings that are transparent in both the visible and IR bands. While there are many suitable bulk materials there are surprisingly few coatings available that offer both antireflecting properties and substrate protection. Materials that need little environmental protection tend to be costly to fabricate and machine while others are far too soft to be of any great use. It is for this reason that particular attention has been given to multispectral zinc sulfide which is a relatively cheap material and has good transparency both in the visible and the IR up to -13micrometers . Although it is a soft material (~150kg.mm-2) it may be protected by a range of coatings. This paper will look at two main materials, ZrN deposited by RF reactive sputtering and YF3 by ion assisted deposition (IAD) which when used in conjunction offer both increased durability to the substrate and good tri-color transmittance for practical window applications.

  19. Applications of antireflection coatings in sonic crystal-based acoustic devices

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Deng, Ke; Xu, Shengjun; Qiu, Chunyin; Yang, Hai; Liu, Zhengyou

    2011-03-01

    The unwanted reflection seriously baffles the practical applications of sonic crystals, such as for various acoustic lenses designed by utilizing the in-band properties of sonic crystals. Herein we introduce the concept of the antireflection coating into the sonic crystal-based devices. The efficiency of such accessorial structures is demonstrated well by an originally high reflection system. Promising perspectives can be anticipated in extending the antireflection coating layers into more general acoustic applications through a flexible design process.

  20. Broad Band Antireflection Coatings for Silicon and Germanium Substrates.

    NASA Astrophysics Data System (ADS)

    Bezuidenhout, Dirk Francois

    Infrared antireflection coatings for silicon and germanium substrates and some of the associated problems are addressed in this thesis. One of the first problems identified and investigated was that of the adhesion of ZnS films to germanium substrates. The cleaning of the Ge discs was evaluated by means of Auger spectroscopy. The main contaminant species found were carbon, oxygen and in the case of germanium substrates sulphur. No sulphur was found on silicon substrates. A wash in a series of organic solutions followed by a bake inside the vacuum chamber lead to much improved though still not acceptable adhesion of ZnS films to germanium substrates. The influence of a contact layer between the substrate and ZnS was investigated. Firstly, metal contact layers (Ni, Cr, Cu) were tried to improve the adhesion of the ZnS films. These samples (germanium-metal-zinc sulphide) were annealed in air in order to transfer the germanium -metal film to a germanide region and thus high optical transmission at long wave-lengths. Slight absorption still results even after the annealing of these samples. A dielectric material, Y_2O_3 , was therefore tested replacing the metal films. The system Ge-Y_2O_3 -ZnS in conjunction with an organic wash and vacuum bake lead to excellent adhesion of the ZnS layers to the germanium substrates. The next problem area addressed was that of a low refractive index material replacement for ThF _4. Four materials were investigated, i.e. ZnS, PbF_2, Y_2O _3 and YF_3. The refractive indices found for these compounds in thin film form at a wavelength of 10 μm is 2,18 for ZnS, 1,7 for PbF_2, 1,42 for Y_2O_3 and 1,3 for YF_3. From these results YF_3 was chosen as low refractive index material in the coating designs. Multi-layer coatings incorporating ZnS, Ge and YF_3 films were designed and evaporated. Measured reflectance values below 0,2% were obtained from 9 μm to 11 mum. These systems were stable and robust. Finally, a silicon ball lens was

  1. Thin film type 248-nm bottom antireflective coatings

    NASA Astrophysics Data System (ADS)

    Enomoto, Tomoyuki; Nakayama, Keisuke; Mizusawa, Kenichi; Nakajima, Yasuyuki; Yoon, Sangwoong; Kim, Yong-Hoon; Kim, Young-Ho; Chung, Hoesik; Chon, Sang Mun

    2003-06-01

    A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 0.13-micron, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity towards resist. SAMSUNG Electronics has developed the advanced Organic BARC with Nissan Chemical Industries, Ltd. and Brewer Science, Inc. for achieving the above purpose. As a result, the suitable high performance SNAC2002 series KrF Organic BARCs were developed. Using CF4 gas as etchant, the plasma etch rate of SNAC2002 series is about 1.4 times higher than that of conventional KrF resists and 1.25 times higher than the existing product. The SNAC2002 series can minimize the substrate reflectivity at below 40nm BARC thickness, shows excellent litho performance and coating properties.

  2. Reactively evaporated multilayer antireflection coatings for Ge optical window

    NASA Astrophysics Data System (ADS)

    Asghar, M. H.; Placido, F.; Naseem, S.

    2007-04-01

    Two multilayer antireflection (AR) coating configurations are designed, prepared and characterized. These AR coatings are designed for a 1 mm thick Ge optical window in the 3.25-5.25 µm band. Ta2O5 and TiO2 are used as high index materials along with SiO2 as low index material. Configuration 1 comprises nine alternating layers of SiO2 and Ta2O5, whereas configuration 2 comprises seven alternating layers of SiO2 and TiO2. Post-deposition annealing is also carried out in the temperature range 150-450 °C for 10 h. The prepared multilayered structures are characterized optically and structurally using a spectrophotometer, an atomic force microscope, x-ray diffraction and a scanning electron microscope. Optical characterization shows that multilayered structures have high absorption for as-deposited samples. A considerable improvement in the transmission profiles for the two multilayered configurations is observed at 350 °C with peak and average transmission for both the configurations exceeding 90%. The as-prepared samples show predominantly amorphous-like structure with pronounced peaks for configuration 2 only. Delamination (for configuration 1) and cracking (for configuration 2) of the multilayered structures are witnessed at an annealing temperature of 450 °C.

  3. Graded index antireflective coatings for glass. Second annual report

    SciTech Connect

    Haggerty, J.S.

    1980-05-01

    M.I.T. is conducting research which will lead to a process for forming broad band antireflective (AR) coatings on glass. Use of these coatings increases the extractable heat from flat-plate solar collectors by 30 to 50% compared with their performance under equivalent solar flux, surface temperature and ambient conditions without broad band AR coatings. Graded index surface films can virtually eliminate reflection losses if controlled properly. Graded index films on a borosilicate glass (Corning Glass Works No. 7740, Pyrex) has been demonstrated. While glass treated this way exhibited adequate optical properties, the glass itself, cannot be fabricated by the float glass process because of excessive working temperatures, and consequently is too expensive for solar applications. The objective of this work is to define glass compositions and processing steps which will result in graded index surface films (which exhibit broad band AR characteristics) on glasses which can be fabricated by the float glass process. The mechanism by which these graded index surface films are produced on glass surfaces consists of preferentially etching one phase from a phase separated glass. The film which remains consists of a porous structure in which the fraction of solid phase increases continuously from the free surface toward the bulk glass. Scattering effects are eliminated by limiting the size of the pore structure to dimensions which are substantially less than the wavelength of light. With this structure, the local index of refraction is proportional to the fraction of solid phase which is present. Characterizations are intended to define the microstructural and chemical nature of the surface film throughout its thickness. Progress is reported. (WHK)

  4. Transformation-optics-inspired anti-reflective coating design for gradient index lenses.

    PubMed

    Morgan, Kenneth L; Brocker, Donovan E; Campbell, Sawyer D; Werner, Douglas H; Werner, Pingjuan L

    2015-06-01

    Recent developments in transformation optics have led to burgeoning research on gradient index lenses for novel optical systems. Such lenses hold great potential for the advancement of complex optics for a wide range of applications. Despite the plethora of literature on gradient index lenses, previous works have not yet considered the application of anti-reflective coatings to these systems. Reducing system reflections is crucial to the development of this technology for highly sensitive optical applications. Here, we present effective anti-reflective-coating designs for gradient index lens systems. Conventional anti-reflective-design methodologies are leveraged in conjunction with transformation optics to develop coatings that significantly reduce reflections of a flat gradient index lens. Finally, the resulting gradient-index anti-reflective coatings are compared and contrasted with conventional homogeneous anti-reflective coatings. PMID:26030547

  5. Optimization of antireflection coating design for multijunction solar cells and concentrator systems

    NASA Astrophysics Data System (ADS)

    Valdivia, Christopher E.; Desfonds, Eric; Masson, Denis; Fafard, Simon; Carlson, Andrew; Cook, John; Hall, Trevor J.; Hinzer, Karin

    2008-06-01

    Photovoltaic solar cells are a route towards local, environmentally benign, sustainable and affordable energy solutions. Antireflection coatings are necessary to input a high percentage of available light for photovoltaic conversion, and therefore have been widely exploited for silicon solar cells. Multi-junction III-V semiconductor solar cells have achieved the highest efficiencies of any photovoltaic technology, yielding up to 40% in the laboratory and 37% in commercial devices under varying levels of concentrated light. These devices benefit from a wide absorption spectrum (300- 1800 nm), but this also introduces significant challenges for antireflection coating design. Each sub-cell junction is electrically connected in series, limiting the overall device photocurrent by the lowest current-producing junction. Therefore, antireflection coating optimization must maximize the current from the limiting sub-cells at the expense of the others. Solar concentration, necessary for economical terrestrial deployment of multi-junction solar cells, introduces an angular-dependent irradiance spectrum. Antireflection coatings are optimized for both direct normal incidence in air and angular incidence in an Opel Mk-I concentrator, resulting in as little as 1-2% loss in photocurrent as compared to an ideal zero-reflectance solar cell, showing a similar performance to antireflection coatings on silicon solar cells. A transparent conductive oxide layer has also been considered to replace the metallic-grid front electrode and for inclusion as part of a multi-layer antireflection coating. Optimization of the solar cell, antireflection coating, and concentrator system should be considered simultaneously to enable overall optimal device performance.

  6. General optimization of tapered anti-reflective coatings.

    PubMed

    Good, Brandon L; Simmons, Shaun; Mirotznik, Mark

    2016-07-25

    An efficient, general optimized method is outlined that achieves antireflective tapers using lossless, non-dispersive dielectrics. The method modifies the derivative of a perfect antireflective wave amplitude distribution rather than the index of refraction distribution. Modifying the derivative of the wave amplitude distribution minimizes the potential index of refraction distributions and ensures perfect antireflection at one frequency, incidence angle, and linear polarization combination. Additional combinations of frequency, incident angle, and linear polarization can be targeted at a particular reflection coefficient within the optimization. After the method is outlined, three examples are shown with one being fabricated and validated at radiofrequencies. PMID:27464116

  7. Inorganic antireflective coating process for deep-UV lithography

    NASA Astrophysics Data System (ADS)

    He, Qizhi; Lee, Wei W.; Hanratty, Maureen A.; Rogers, Daty; Xing, Guoqiang; Singh, Abha; Zielinski, Eden

    1998-06-01

    Antireflective coatings (ARCs) have been used to enhance IC lithography for years, however, many conventional bottom ARCs can no longer maintain acceptable linewidth control, cannot meet stringent deep-UV (DUV) photoresist processing requirements, and increase the etch complexity. In this paper, we report the development of an inorganic ARC for DUV lithography in sub-0.25 micrometer advanced device applications. Plasma-enhanced chemical vapor deposition (PECVD) is employed to deposit a dielectric film silicon oxynitride (SixOyNz) with specific optical properties. The three optical parameters of the SixOyNz film: refractive index n, extinction coefficient k, and thickness d are specifically designed to ensure that the reflection light that passes through the ARC/substrate is equal in amplitude and opposite in phase to the reflected light from the resist/ARC interface. The reflection light is canceled by destructive interference and therefore photoresist receives the minimum substrate reflection wave. Using this technique, we have successfully patterned features at 0.25 micrometer and below. The dielectric film can not only function as an ARC layer, but also serve as a hardmask for the pattern transfer etch process. With an aggressive etch bias process, linewidths down to 0.60 micrometer poly-Si gate are achieved with good linewidth control (3(sigma) less than 12 nm) and a near perfect linearity. For the marginal metal etch resistance of DUV photoresist, the designed SixOyNz is effective in imparting more etch resistance and suppressing metal substrate reflection. Excellent optical uniformity of the n, k and thickness d of the SixOyNz ARC is obtained with a manufacturable PECVD deposition process.

  8. Wideband antireflection coatings on germanium and filters for second optical window

    NASA Astrophysics Data System (ADS)

    Ciosek, Jerzy; Firak, Jozef; Stanislawek, Urszula; Kwasny, Miroslaw; Kopczynski, Krzysztof

    2003-10-01

    The investigation results of wideband (8-12 μm) antireflection coatings on germanium substrate and spectral characteristics of interference wideband filter for spectral range of 8-12 μm are presented. For design of filters and antireflection coatings the following layer materials were used: Ge, ZnS and Mira, and substrate materials such as: Ge for antireflection coatings and ZnSe for interference filters. Wideband filter for the range of 8-12 μm requires application of additional two filters cutting off radiation from the range of 1-7 μm. The cutting off filters are interference filters for which construction germanium, Mira, and ZnS were used. The constructions of basic and cutting off filters were designed considering technical possibilities of vacuum device BAK 550 of the Balzers firm.

  9. Effects of positive ion implantation into antireflection coating of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Middleton, A. E.; Harpster, J. W.; Collis, W. J.; Kim, C. K.

    1971-01-01

    The state of technological development of Si solar cells for highest obtained efficiency and radiation resistance is summarized. The various theoretical analyses of Si solar cells are reviewed. It is shown that factors controlling blue response are carrier diffusion length, surface recombination, impurity concentration profile in surface region, high level of surface impurity concentration (degeneracy), reflection coefficient of oxide, and absorption coefficient of Si. The theory of ion implantation of charge into the oxide antireflection coating is developed and side effects are discussed. The experimental investigations were directed at determining whether the blue response of Si solar cells could be improved by phosphorus ion charges introduced into the oxide antireflection coating.

  10. Anti-reflective and anti-soiling coatings for self-cleaning properties

    DOEpatents

    Brophy, Brenor L.; Nair, Vinod; Dave, Bakul Champaklal

    2016-05-31

    The disclosure discloses abrasion resistant, persistently hydrophobic and oleophobic, anti-reflective and anti-soiling coatings for glass. The coatings described herein have wide application, including for example the front cover glass of solar modules. Methods of applying the coatings using various apparatus are disclosed. Methods for using the coatings in solar energy generation plants to achieve greater energy yield and reduced operations costs are disclosed. Coating materials are formed by combinations of hydrolyzed silane-base precursors through sol-gel processes. Several methods of synthesis and formulation of coating materials are disclosed.

  11. Tuning the peak position of subwavelength silica nanosphere broadband antireflection coatings

    PubMed Central

    2014-01-01

    Subwavelength nanostructures are considered as promising building blocks for antireflection and light trapping applications. In this study, we demonstrate excellent broadband antireflection effect from thin films of monolayer silica nanospheres with a diameter of 100 nm prepared by Langmuir-Blodgett method on glass substrates. With a single layer of compact silica nanosphere thin film coated on both sides of a glass, we achieved maximum transmittance of 99% at 560 nm. Furthermore, the optical transmission peak of the nanosphere thin films can be tuned over the UV-visible range by changing processing parameters during Langmuir-Blodgett deposition. The tunable optical transmission peaks of the Langmuir-Blodgett films were correlated with deposition parameters such as surface pressure, surfactant concentration, ageing of suspensions and annealing effect. Such peak-tunable broadband antireflection coating has wide applications in diversified industries such as solar cells, windows, displays and lenses. PMID:25136278

  12. Tuning the peak position of subwavelength silica nanosphere broadband antireflection coatings.

    PubMed

    Tao, Fei; Hiralal, Pritesh; Ren, Lianbing; Wang, Yong; Dai, Qing; Amaratunga, Gehan Aj; Zhou, Hang

    2014-01-01

    Subwavelength nanostructures are considered as promising building blocks for antireflection and light trapping applications. In this study, we demonstrate excellent broadband antireflection effect from thin films of monolayer silica nanospheres with a diameter of 100 nm prepared by Langmuir-Blodgett method on glass substrates. With a single layer of compact silica nanosphere thin film coated on both sides of a glass, we achieved maximum transmittance of 99% at 560 nm. Furthermore, the optical transmission peak of the nanosphere thin films can be tuned over the UV-visible range by changing processing parameters during Langmuir-Blodgett deposition. The tunable optical transmission peaks of the Langmuir-Blodgett films were correlated with deposition parameters such as surface pressure, surfactant concentration, ageing of suspensions and annealing effect. Such peak-tunable broadband antireflection coating has wide applications in diversified industries such as solar cells, windows, displays and lenses. PMID:25136278

  13. Reflectance Profile of BaTiO3 on Multilayer Antireflection Coating Systems

    NASA Astrophysics Data System (ADS)

    Karaomerlioglu, Filiz

    2011-05-01

    Antireflection (AR) coating systems are very important technology for optoelectronic devices. The optical characteristics of the system can be regulated by external electric or thermal field, and designed broadband ultra low reflection coating systems. It is investigated optical properties of multilayer AR coatings based on different ferroelectric materials to reduce reflectance in other studies. In this study, reflectance profile of BaTiO3 on multilayer AR coating systems has been developed in the visible region. It has been used ZnSe and ZrO2 as multilayer AR coatings, and BaTiO3 as the substrate. Fortran program has been simulated on Fresnell equations base.

  14. Reactively sputtered silicon oxy-nitride films for solar absorber anti-reflection coatings

    NASA Astrophysics Data System (ADS)

    Wilson, A. D.

    1984-05-01

    The optical properties of films of SiO(x)N(y) produced by reactive sputtering in argon/oxygen/nitrogen are reported. The refractive index of the films can be continuously varied between 1.46 and 3.4. This large range of index allows considerable freedom in the design of multilayer thin film stacks. The practical use of these films is demonstrated by the fabrication of double layer antireflection coatings for amorphous silicon based solar thermal absorbers. An AM1 solar absorptance of 0.95 has been obtained with an emittance increment due to the antireflecting layers of only 0.055. Other possible uses are also identified.

  15. Moth eye antireflection coated GaInP/GaAs/GaInNAs solar cell

    NASA Astrophysics Data System (ADS)

    Aho, Arto; Tommila, Juha; Tukiainen, Antti; Polojärvi, Ville; Niemi, Tapio; Guina, Mircea

    2014-09-01

    The performance of a GaInP/GaAs/GaInNAs solar cell incorporating AlInP moth eye antireflection coating is reported and compared with the performance of a similar cell comprising TiO2/SiO2 antireflection coating. The moth eye coating exhibits an average reflectance of only 2% within the spectral range from 400 nm to 1600 nm. EQE measurements revealed absorption-related losses in the AlInP moth eye coating at wavelengths below 510 nm. Short wavelength absorption decreases the current generation in the top GaInP junction by 10%. Despite the absorption losses, the moth eye patterned GaInP/GaAs/GaInNAs solar cell exhibited higher current generation under AM1.5G real sun illumination.

  16. Ge 1- xC x double-layer antireflection and protection coatings

    NASA Astrophysics Data System (ADS)

    Hu, C. Q.; Zheng, W. T.; Li, J. J.; Jiang, Q.; Tian, H. W.; Lu, X. Y.; Liu, J. W.; Xu, L.; Wang, J. B.

    2006-09-01

    The antireflection Germanium carbide (Ge 1- xC x) coating, deposited using RF reactive sputtering, on both sides of ZnS substrate wafer has been developed. The infrared (IR) transmittance spectra show that the IR transmittance in the wavelength region between 8 and 12 μm for the designed system Ge 1- xC x/ZnS/Ge 1- xC x is greatly enhanced compared to that for ZnS substrate. In addition, the double-layer coated ZnS substrate is approximately four times as hard as uncoated ZnS substrate. This investigation indicates that a double-layer Ge 1- xC x coating can be used as an effective antireflection and protection coating on ZnS infrared window.

  17. Anti-reflection coatings applied by acid-leaching process. Final report

    SciTech Connect

    Pastirik, E.

    1980-09-01

    The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar cell panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

  18. Plasma-enhanced CVD silicon nitride antireflection coatings for solar cells

    NASA Technical Reports Server (NTRS)

    Johnson, C. C.; Wydeven, T.; Donohoe, K.

    1983-01-01

    Multilayer plasma-enhanced chemical vapor deposition (PECVD) silicon nitride antireflection coatings were deposited on space quality silicon solar cells. Preliminary experiments indicated that multilayer coatings decreased the total reflectance of polished silicon from 35 percent to less than 3 percent over the spectral range 0.4-1.0 micron. The solar cell energy conversion efficiency was increased from an average of 8.84 percent to an average of 12.63 percent.

  19. Modified porous silica antireflective coatings with laser damage resistance for Ti:sapphire

    NASA Astrophysics Data System (ADS)

    Jia, Qiaoying; Li, Haiyuan; Liu, Ruijun; Tang, Yongxing; Jiang, Zhonghong

    2005-04-01

    Porous SiO2 antireflective (AR) coatings are prepared from the colloidal silica solution modified with methyltriethoxysilane (MTES) based on the sol-gel route. The viscosity of modified silica suspensions changes but their stability keeps when MTES is introduced. The refractive indices of modified coatings vary little after bake treatment from 100 to 150 Celsius. The modified silica coatings on Ti:sapphire crystal, owning good homogeneity, display prominent antireflective effect within the laser output waveband (750-850 nm) of Ti:sapphire lasers, with average transmission above 98.6%, and own laser induced damage thresholds (LIDTs) of more than 2.2 J/cm2 at 800 nm with the pulse duration of 300 ps.

  20. High performance anti-reflection coatings for broadband multi-junction solar cells

    SciTech Connect

    AIKEN,DANIEL J.

    2000-02-23

    The success of bandgap engineering has made high efficiency broadband multi-junction solar cells possible with photo-response out to the band edge of Ge. Modeling has been conducted which suggests that current double layer anti-reflection coating technology is not adequate for these devices in certain cases. Approaches for the development of higher performance anti-reflection coatings are examined. A new AR coating structure based on the use of Herpin equivalent layers is presented. Optical modeling suggests a decrease in the solar weighted reflectance of over 2.5{percent} absolute as a result. This structure requires no additional optical material development and characterization because no new optical materials are necessary. Experimental results and a sensitivity analysis are presented.

  1. Anti-reflection Coating for Cryogenic Silicon and Alumina Lenses in Millimeter-Wave Bands

    NASA Astrophysics Data System (ADS)

    Nitta, Tom; Sekiguchi, Shigeyuki; Sekimoto, Yutaro; Mitsui, Kenji; Okada, Norio; Karatsu, Kenichi; Naruse, Masato; Sekine, Masakazu; Matsuo, Hiroshi; Noguchi, Takashi; Seta, Masumichi; Nakai, Naomasa

    2014-09-01

    A dielectric lens with high refractive index is suitable for focusing cryogenic devices in millimeter-wave bands when an appropriate anti-reflection (AR) coating is applied. Two types of AR coatings for silicon and alumina were studied at the millimeter-wave (220 GHz) band: one is by direct machining of mixed epoxy for a silicon lens array, while the other is by laser machining of an antireflective subwavelength structure for a large alumina lens used in a re-imaging optics system. The millimeter-wave optical properties of silicon, alumina, aluminum nitride, and Stycast epoxies were measured with a Fourier Transform Spectrometer (FTS) at cryogenic temperatures. The measured refractive index of the AR coating with a mixture of Stycast 1266 (n = 1.68) and Stycast 2850FTJ (n = 2.2) for silicon at 30 K was 1.84. The thickness of the epoxy AR coating was precisely controlled with direct machining. Transmittance of the AR-coated silicon substrate, measured with FTS, was approximately 95 % at the center frequency of the 220 GHz band with a bandwidth of 25 % at 27 K. An antireflective subwavelength structure was designed for an alumina sample with periodic cylindrical holes. The measured 220-GHz-band transmittance was above 90 % with a bandwidth of 25 % at 25 K.

  2. Enhanced light extraction of Bi3Ge4O12 scintillator by graded-refractive-index antireflection coatings

    NASA Astrophysics Data System (ADS)

    Tong, Fei; Liu, Bo; Chen, Hong; Zhu, Zhichao; Gu, Mu

    2013-08-01

    A three-layer graded-refractive-index antireflection coating is designed and prepared on the one surface of the Bi3Ge4O12 scintillator by sol-gel technology. The emission intensity of the Bi3Ge4O12 with a graded-refractive-index antireflection coating exhibits a broadband and omnidirectional enhancement of 15.9% compared with the reference sample without coating. This significant enhancement is attributed to the decrease of Fresnel reflection, which is consistent with the measurement of transmission spectra. Additionally, it is evident that the graded-refractive-index coating is superior to the conventional quarter-wave coating due to the omnidirectionality advantage.

  3. Fabrication of superhydrophilic and antireflective silica coatings on poly(methyl methacrylate) substrates

    SciTech Connect

    Geng, Zhi; He, Junhui; Xu, Ligang

    2012-06-15

    Graphical abstract: Self-cleaning and antireflection properties were successfully achieved by assembling (PDDA/S-20){sub n} coatings on PMMA substrates followed by oxygen plasma treatment. Highlights: ► Porous silica coatings were created by layer-by-layer assembly on PMMA substrates. ► Silica coatings were treated by oxygen plasma. ► Porous silica coatings were highly antireflective and superhydrophilic on PMMA substrates. -- Abstract: Silica nanoparticles of ca. 20 nm in size were synthesized, from which hierarchically porous silica coatings were fabricated on poly(methyl methacrylate) (PMMA) substrates via layer-by-layer (LbL) assembly followed by oxygen plasma treatment. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 99%, whereas that of the PMMA substrate is only 92%. After oxygen plasma treatment, the time for a water droplet to spread to a contact angle of lower than 5° decreased to as short as 0.5 s. Scanning and transmission electron microscopy were used to observe the morphology and structure of nanoparticles and coating surfaces. Transmission and reflection spectra were recorded on UV–vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.

  4. Interference multilayer antireflection coatings for two wavelengths in the near infrared

    NASA Astrophysics Data System (ADS)

    Pencheva, Tamara G.; Nenkov, Milen; Michev, Javor

    2001-04-01

    The investigation deals with analysis of antireflection coatings of two transparent materials with high (H) and low (L) refractive index for two wavelengths 1.30 micrometer and 1.55 micrometer in the near IR on glass/silica substrates. The results are obtained by numerical optimization approach which algorithms are realized using programming language DELPHI. The initial structures of LHL three-layer and LHLH four-layer coating (optimized for both wavelengths) are modifications of double-layer antireflection coating for one wavelength 1.4 micrometer. It is shown that the highest transmittance near 1.30 and 1.55 micrometer (practically equal to 100%) shows LHLH four-layer coating structure. The total physical and optical thickness of optimized LHLH four-layer coating is smaller than corresponding value for optimized LHL three-layer coating. Four-layer LHLH coating is more stable with respect to small n and d variations and corresponding transmittance changes are less than in case of LHL three-layer coating.

  5. Observation of the waveguide resonance in a periodically patterned high refractive index broadband antireflection coating.

    PubMed

    Stenzel, O; Wilbrandt, S; Chen, X; Schlegel, R; Coriand, L; Duparré, A; Zeitner, U; Benkenstein, T; Wächter, C

    2014-05-10

    Grating waveguide structures have been prepared by the deposition of a high refractive index broadband antireflection coating onto a patterned fused silica substrate. Aluminum oxide and hafnium oxide as well as mixtures thereof have been used as coating materials. Optical reflection measurements combined with atomic force microscopy have been used to characterize the structures. Upon illumination with a TE wave, the best structure shows a narrow reflection peak located at 633 nm at an incidence angle of about 17°. The peak reflectance of that sample accounts for more than 89%. Off-resonance interference structures appear strongly suppressed in the spectrum between 450 and 800 nm because of the characteristics of the designed antireflection layer. The structure thus possesses a notch filter spectral characteristic in a broad spectral range. PMID:24922038

  6. Bifacial silicon solar cells in space: Antireflection (AR) coatings and thermal behavior

    NASA Astrophysics Data System (ADS)

    Correig, X.; Calderer, J.

    1986-11-01

    An approach to antireflection coating (ARC) design which recognizes that bifacial silicon solar cell efficiency is related to antireflection coating design and operating temperature by optical, electrical, and thermal behavior of the structure, is proposed. Maximum efficiency coincides neither with minimum temperature nor maximum absorptance. A compromise among these variables can be reached. Calculations make it possible to design ARC to reach an absorptance value near 0.6. Calculations of back side reflectance show that reflectance of isotropic incident light is larger than that of normal incident. Efficiency values are much less affected by ARC thickness. Mass budgets of bifacial arrays are similar to those of monofacial ones, so the only difference in thermal cycle amplitude is due to differences in operating temperature.

  7. Antireflection coatings with SiOx-TiO2 multilayer structures

    NASA Astrophysics Data System (ADS)

    Lu, Jong-Hong; Luo, Jen-Wei; Chuang, Shiou-Ruei; Chen, Bo-Ying

    2014-11-01

    In this study, we used SiOx-TiO2 multilayer antireflective coatings to achieve optical average transmittances of 94.93 and 98.07% for one-sided and double-sided coatings on a glass substrate, respectively. A SiOx film was employed as the material with a low refractive index and a TiO2 film as the material with a high refractive index. Results showed that when any layer thickness of the SiOx-TiO2 nano-multilayer (NML) structure is much less than the wavelength of visible light, the SiOx-TiO2 thickness ratio can be used to adjust the optical refractive index of the entire NML film. In this study, we produced dense antireflective coatings of three layers (SiOx, TiO2, and SiOx-TiO2 NML/glass substrate) and four layers (SiOx, TiO2, SiOx, and TiO2/glass substrate) with film thicknesses and refractive indices controlled by reactive magnetron sputtering. Thermal treatment at 600 °C in an air atmosphere was also shown to reduce the absorption of visible light, resolving the issue of degraded transparency caused by increasing sputtering speed. The microhardness of the antireflective film was 8.44 GPa, similar to that of the glass substrate. Process window analysis demonstrated the feasibility of the antireflective coating process window from an engineering standpoint. The thickness of the film deviated by less than 10% from the ideal thickness, corresponding to a 98% transmittance range, and the simulation and experimental results were relatively consistent.

  8. Plasma polymerized coating for polycarbonate - Single layer, abrasion resistant, and antireflection

    NASA Technical Reports Server (NTRS)

    Wydeven, T.

    1977-01-01

    Plasma polymerized vinyltrimethoxy silane films were deposited on transparent polycarbonate substrates. The adherent, clear films protected the substrates from abrasion and also served as antireflection coatings. Posttreatment of the vinyltrimethoxy silane films in an oxygen glow discharge further improved the abrasion resistance. ESCA (electron spectroscopy for chemical analysis) and IR transmission spectra of some films were recorded, and an elemental analysis of the films was obtained.

  9. Far-infrared filters utilizing small particle scattering and antireflection coatings

    NASA Technical Reports Server (NTRS)

    Armstrong, K. R.; Low, F. J.

    1974-01-01

    High-transmission, low-pass scatter filters for blocking at wavelengths from 3.5 to 50 microns and single-layer antireflection coatings for optical materials used in the 25- to 300-micron region of the spectrum are described. The application of both techniques to liquid-He-cooled filters permits the construction of efficient low-pass and medium-width bandpass filters for use throughout the far infrared.

  10. Moisture resistant and anti-reflection optical coatings produced by plasma polymerization of organic compounds

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1975-01-01

    The need for protective coatings on critical optical surfaces, such as halide crystal windows or lenses used in spectroscopy, has long been recognized. It has been demonstrated that thin, one micron, organic coatings produced by polymerization of flourinated monomers in low temperature gas discharge (plasma) exhibit very high degrees of moisture resistence, e.g., hundreds of hours protection for cesium iodide vs. minutes before degradation sets in for untreated surfaces. The index of refraction of these coatings is intermediate between that of the halide substrate and air, a condition for anti-reflection, another desirable property of optical coatings. Thus, the organic coatings not only offer protection, but improved transmittance as well. The polymer coating is non-absorbing over the range 0.4 to 40 microns with an exception at 8.0 microns, the expected absorption for C-F bonds.

  11. Single-Step Soft-Imprinted Large-Area Nanopatterned Antireflection Coating.

    PubMed

    van de Groep, Jorik; Spinelli, Pierpaolo; Polman, Albert

    2015-06-10

    We demonstrate an effective nanopatterned antireflection coating on glass that is based on sol-gel chemistry and large-area substrate-conformal soft-imprint technology. The printed 120 nm tall silica nanocylinders with a diameter of 245 nm in a square array with 325 nm pitch form an effective-index (n = 1.20) antireflection coating that reduces the double-sided reflection from a borosilicate glass slide from 7.35% to 0.57% (averaged over the visible spectral range) with a minimum reflectance <0.05% at 590 nm. The nanoglass coating is made using a simple process involving only spin-coating and an imprint step, without vacuum technology or annealing required. The refractive index of the nanoglass layers can be tailored over a broad range by controlling the geometry (1.002 < n < 1.44 in theory), covering a wide range that is not achievable with natural materials. We demonstrate that the nanoglass coating effectively eliminates glare from smart-phone display windows and significantly improves the efficiency of glass-encapsulated solar cells. These features, that are achieved over an angular range as wide as ±50°, together with strong hydrophobicity and mechanical durability, make nanoglass coatings a promising technology to improve the functionality of optoelectronic devices based on glass encapsulation. PMID:26010375

  12. Wideband antireflection coatings combining interference multilayers and subwavelength structures prepared by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Bruynooghe, S.; Helgert, M.; Challier, M.; Tonova, D.; Sundermann, M.; Koch, T.; Gatto, A.; Schulze, M.; Kley, E.-B.

    2015-08-01

    To further reduce the intensity of the Fresnel reflections of optical components, subwavelength structures prepared by reactive ion etching of SiO2 thin films are combined as outermost layer with a multilayer system made of conventional thin film materials and prepared by magnetron sputtering. In this approach, a hybrid coating is realized in which the nanoscaled structured outermost layer is expected to further improve the antireflection properties of common interference stacks. The subwavelength structures are examined by spectroscopic ellipsometry, spectral photometry and scanning electron microscopy. The microscopic and optical spectroscopic analysis revealed that pillar-shaped nanostructures are formed during etching which exhibit low-index properties and have a depth-dependent refractive index. To take into account the index gradient in the coating design, the optical properties of the nanostructures are modeled using the effective medium approximation. The calculated average effective refractive index is 1.11 at 500 nm wavelength. A hybrid coating was designed to minimize the residual reflectance in the 400 - 900 nm spectral range for BK7 glass substrate. Experimental results showed that the hybrid coating achieves a low residual reflectance with very good omni-directional properties, owing to the properties of its nanostructured surface. The residual reflection of the hybrid coating is found to be two times smaller than the reflection obtained by applying a common interference multilayer system which demonstrates the benefit of the use of hybrid systems for the realization of broadband antireflective coatings with wide-angle properties.

  13. Ion-assisted deposition of yttrium fluoride as a substitute for thorium fluoride: application to infrared antireflection coating on germanium

    NASA Astrophysics Data System (ADS)

    Robic, Jean-Yves; Rolland, Bernard; Deutsch, Jean-Claude; Gallais, Patrick

    1994-11-01

    Yttrium fluoride has been proposed as a substitute for thorium fluoride in anti-reflection coatings for the infrared range. We have studied the ion assisted deposition (IAD) of YF3 in order to obtain dense and low absorbency layers in the 8 to 12 mm spectral window. Refractive index and extinction coefficient of this fluoride were determined from spectrophotometry measurements. We have then associated the YF3 with ZnS and Ge layers so as to obtain four layer anti-reflection coatings on germanium. The stress induced by each layer in the coating was measured and the sum was shown to be equal to the stress of the total coating. Eventually, an industrial, high efficiency, both side anti-reflection coating on germanium was developed using IAD YF3 film.

  14. Broad-bandwidth Metamaterial Antireflection Coatings for Sub-Millimeter Astronomy and CMB Foreground Removal

    NASA Astrophysics Data System (ADS)

    McMahon, Jeff

    Sub-millimeter observations are crucial for answering questions about star and galaxy formation; understanding galactic dust foregrounds; and for removing these foregrounds to detect the faint signature of inflationary gravitational waves in the polarization of the Cosmic Microwave Background (CMB). Achieving these goals requires improved, broad-band antireflection coated lenses and half-wave plates (HWPs). These optical elements will significantly boost the sensitivity and capability of future sub-millimeter and CMB missions. We propose to develop wide-bandwidth metamaterial antireflection coatings for silicon lenses and sapphire HWPs with 3:1 ratio bandwidth that are scalable across the sub-millimeter band from 300 GHz to 3 THz. This is an extension of our successful work on saw cut metamaterial AR coatings for silicon optics at millimeter wave lengths. These, and the proposed coatings consist of arrays of sub-wavelength scale features cut into optical surfaces that behave like simple dielectrics. We have demonstrated saw cut 3:1 bandwidth coatings on silicon lenses, but these coatings are limited to the millimeter wave band by the limitations of dicing saw machining. The crucial advance needed to extend these broad band coatings throughout the sub-millimeter band is the development of laser cut graded index metamaterial coatings. The proposed work includes developing the capability to fabricate these coatings, optimizing the design of these metamaterials, fabricating and testing prototype lenses and HWPs, and working with the PIPER collaboration to achieve a sub-orbital demonstration of this technology. The proposed work will develop potentially revolutionary new high performance coatings for the sub-millimeter bands, and cary this technology to TRL 7 paving the way for its use in space. We anticipate that there will be a wide range of applications for these coatings on future NASA balloons and satellites.

  15. Plasma-polymerized coating for polycarbonate: Single-layer, abrasion resistant, and antireflection

    NASA Technical Reports Server (NTRS)

    Wydeven, Theodore

    1991-01-01

    Plasma-polymerized vinyl trimethoxy silane films were deposited on transparent polycarbonate substrates. The adherent, clear films protected the substrates from abrasion and also served as antireflection coatings. Post-treatment of the vinyl trimethoxy silane films in an oxygen glow discharge further improved their abrasion resistance. The coatings were characterized by elemental analysis of the bulk, ESCA analysis of the surface, transmission, thickness, abrasion resistance, haze, and adhesion. This patented process is currently used by the world's largest manufacturers of non-prescription sunglasses to protect the plastic glasses from scratching and thereby to increase their useful lifetime.

  16. High-performance antireflective coatings with a porous nanoparticle layer for visible wavelengths.

    PubMed

    Murata, Tsuyoshi; Ishizawa, Hitoshi; Tanaka, Akira

    2011-03-20

    Ghosts and flares are well-known problems that are caused by reflections from lens surfaces when we take photographs. It is more difficult to prevent such stray light in a digital camera than in a film camera because of high reflectance from the low-pass filter and diffraction from the image sensor. To prevent such stray light, we introduce an ultralow refractive index layer into the antireflective (AR) coatings. We used the solgel method to form porous fluoride layers with ultralow refractive indices, and we succeeded in developing a unique process to form AR coatings with superior performance. PMID:21460972

  17. Broadband antireflective coatings based on two-dimensional arrays of subwavelength nanopores

    NASA Astrophysics Data System (ADS)

    Baranov, D. A.; Dmitriev, P. A.; Mukhin, I. S.; Samusev, A. K.; Belov, P. A.; Simovski, C. R.; Shalin, A. S.

    2015-04-01

    A broadband thin-film antireflective coating (ARC)—a regular array of nanopores in a dielectric substrate—is studied theoretically and experimentally. Tuning the geometrical parameters of the array allows for strong suppression of reflection. For a fused silica substrate, reflectivity is lower than 1% over a range with a relative bandwidth, 60%-70%, reaching 0.05% in the minimum. The underlying physics is the spatial dispersion in the porous medium which enables phase compensation for the partially reflected waves in a broad band. This allows for more broadband antireflection than any flat homogeneous single-layer ARC can provide. Importantly, the studied ARC is universal for any transparent dielectric substrate.

  18. Fabrication of broadband antireflection coating at terahertz frequency using a hot emboss method

    NASA Astrophysics Data System (ADS)

    Li, YunZhou; Cai, Bin; Zhu, YiMing

    2014-11-01

    We fabricated a terahertz anti-reflective structure on a polystylene by using a hot-embossing method. Polystylene was spin-coated onto a silicon substrate and then transformed by using a metallic mould comprising a bunch of Chinese acupuncture needles. The transformation layer yielded gradient refractive index profiles on the substrate which can reduce the surface reflection effectively. The samples were evaluated by a terahertz time-domain spectroscope. Compared with a bare silicon substrate, we observed an increase of ~30% in the transmittance. We also observed broader bandwidth properties compared with a single-layer antireflective structure. The process imposes no substrate limiting; i.e., it has great potential to be applied onto various THz devices.

  19. A Metasurface Anti-reflection Coating for Enhancing Surface Plasmon-Polariton of Metallic Hole Array

    NASA Astrophysics Data System (ADS)

    Bhattarai, Khagendra; Jeon, Jiyeon; Kim, Jun; Ku, Zahyun; Lee, Sang Jun; Zhou, Jiangfeng; Usf, Usa Collaboration; Kriss, Korea Collaboration; Afrl, Usa Collaboration

    We demonstrate a metasurface made of metallic disk resonator array as an anti-reflection (AR) coating to enhance (reduce) the transmission (reflection) through metal hole array (MHA). Our result show that the simulated (measured) transmission at the first order surface plasmon-polariton (SPP) resonance is increased up to 82 %(88%) compared to uncoated MHA. The electric field of the surface wave is also enhanced by 33%. Using an effective medium theory, we show that the metasurface operates at off-resonance wavelengths and can be understood as a thin film that exhibits high effective permittivity (~30) with very low loss (loss tangent ~0.005). Thus we reveal the mechanism of the metasurface AR coating as the traditional thin film AR coating. With tunable effective permittivity, our structure provides great flexibility to achieve AR coating for general substance at any wavelength.

  20. High durability antireflection coatings for silicon and multispectral ZnS

    NASA Astrophysics Data System (ADS)

    Joseph, Shay; Marcovitch, Orna; Yadin, Ygal; Klaiman, Dror; Koren, Nitzan; Zipin, Hedva

    2007-04-01

    In the current complex battle field, military platforms are required to operate on land, at sea and in the air in all weather conditions both day and night. In order to achieve such capabilities, advanced electro-optical systems are being constantly developed and improved. These systems such as missile seeker heads, reconnaissance and target acquisition pods and tracking, monitoring and alert systems have external optical components (window or dome) which must remain operational even at extreme environmental conditions. Depending on the intended use of the system, there are a few choices of window and dome materials. Amongst the more common materials one can point out sapphire, ZnS, germanium and silicon. Other materials such as spinel, ALON and yittria may also be considered. Most infrared materials have high indices of refraction and therefore they reflect a large part of radiation. To minimize the reflection and increase the transmission, antireflection (AR) coatings are the most common choice. Since these systems operate at different environments and weather conditions, the coatings must be made durable to withstand these extreme conditions. In cases where the window or dome is made of relatively soft materials such as multispectral ZnS, the coating may also serve as protection for the window or dome. In this work, several antireflection coatings have been designed and manufactured for silicon and multispectral ZnS. The coating materials were chosen to be either oxides or fluorides which are known to have high durability. Ellipsometry measurements were used to characterize the optical constants of the thin films. The effects of the deposition conditions on the optical constants of the deposited thin films and durability of the coatings will be discussed. The coatings were tested according to MIL-STD-810E and were also subjected to rain erosion tests at the University of Dayton Research Institute (UDRI) whirling arm apparatus in which one of the coatings showed

  1. Performance of "Moth Eye" Anti-Reflective Coatings for Solar Cell Applications

    SciTech Connect

    Clark, E.; Kane, M.; Jiang, P.

    2011-03-14

    An inexpensive, effective anti-reflective coating (ARC) has been developed at the University of Florida to significantly enhance the absorption of light by silicon in solar cells. This coating has nano-scale features, and its microstructure mimics that of various night active insects (e.g. a moth's eye). It is a square array of pillars, each about 700 nm high and having a diameter of about 300 nm. Samples of silicon having this coating were exposed either to various combinations of either elevated temperature and humidity or to gamma irradiation ({sup 60}Co) at the Savannah River National Laboratory, or to a broad spectrum ultraviolet light and to a 532 nm laser light at the University of Florida. The anti-reflective properties of the coatings were unaffected by any of these environmental stresses, and the microstructure of the coating was also unaffected. In fact, the reflectivity of the gamma irradiated ARC became lower (advantageous for solar cell applications) at wavelengths between 400 and 1000 nm. These results show that this coating is robust and should be tested in actual systems exposed to either weather or a space environment. Structural details of the ARCs were studied to optimize their performance. Square arrays performed better than hexagonal arrays - the natural moth-eye coating is indeed a square array. The optimal depth of the templated nanopillars in the ARC was investigated. A wet etching technology for ARC formation was developed that would be less expensive and much faster than dry etching. Theoretical modeling revealed that dimple arrays should perform better than nipple arrays. A method of fabricating both dimple and nipple arrays having the same length was developed, and the dimple arrays performed better than the nipple arrays, in agreement with the modeling. The commercial viability of the technology is quite feasible, since the technology is scalable and inexpensive. This technology is also compatible with current industrial fabrication of

  2. Atomic Layer Deposition of Chemical Passivation Layers and High Performance Anti-Reflection Coatings on Back-Illuminated Detectors

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Nikzad, Shouleh (Inventor)

    2014-01-01

    A back-illuminated silicon photodetector has a layer of Al2O3 deposited on a silicon oxide surface that receives electromagnetic radiation to be detected. The Al2O3 layer has an antireflection coating deposited thereon. The Al2O3 layer provides a chemically resistant separation layer between the silicon oxide surface and the antireflection coating. The Al2O3 layer is thin enough that it is optically innocuous. Under deep ultraviolet radiation, the silicon oxide layer and the antireflection coating do not interact chemically. In one embodiment, the silicon photodetector has a delta-doped layer near (within a few nanometers of) the silicon oxide surface. The Al2O3 layer is expected to provide similar protection for doped layers fabricated using other methods, such as MBE, ion implantation and CVD deposition.

  3. Antireflective coatings for multijunction solar cells under wide-angle ray bundles.

    PubMed

    Victoria, Marta; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2012-03-26

    Two important aspects must be considered when optimizing antireflection coatings (ARCs) for multijunction solar cells to be used in concentrators: the angular light distribution over the cell created by the particular concentration system and the wide spectral bandwidth the solar cell is sensitive to. In this article, a numerical optimization procedure and its results are presented. The potential efficiency enhancement by means of ARC optimization is calculated for several concentrating PV systems. In addition, two methods for ARCs direct characterization are presented. The results of these show that real ARCs slightly underperform theoretical predictions. PMID:22453483

  4. Optimized 2D array of thin silicon pillars for efficient antireflective coatings in the visible spectrum

    PubMed Central

    Proust, Julien; Fehrembach, Anne-Laure; Bedu, Frédéric; Ozerov, Igor; Bonod, Nicolas

    2016-01-01

    Light reflection occuring at the surface of silicon wafers is drastically diminished by etching square pillars of height 110 nm and width 140 nm separated by a 100 nm gap distance in a square lattice. The design of the nanostructure is optimized to widen the spectral tolerance of the antireflective coatings over the visible spectrum for both fundamental polarizations. Angle and polarized resolved optical measurements report a light reflection remaining under 5% when averaged in the visible spectrum for both polarizations in a wide angular range. Light reflection remains almost insensitive to the light polarization even in oblique incidence. PMID:27109643

  5. Investigation on antireflection coating for high resistance to potential-induced degradation

    NASA Astrophysics Data System (ADS)

    Mishina, Ken; Ogishi, Atsufumi; Ueno, Kiyoshi; Doi, Takuya; Hara, Kohjiro; Ikeno, Norihiro; Imai, Daisuke; Saruwatari, Tetsuya; Shinohara, Makoto; Yamazaki, Toshiharu; Ogura, Atsushi; Ohshita, Yoshio; Masuda, Atsushi

    2014-01-01

    In this study, we focus on the relationship between potential-induced degradation (PID) and characteristics of antireflection coating (ARC) on crystalline silicon solar cells. We evaluated the PID of general industrial multicrystalline p-type silicon solar cell groups with various ARCs. The module, which has an ARC deposited by plasma-enhanced chemical vapor deposition (PE-CVD) using a hollow cathode, indicated high resistance to PID with maintained conventional refractive index (RI). This ARC had properties of high conductivity and low oxygen concentration. It has the potential to suppress PID on crystalline silicon solar cells with maintained conventional RI.

  6. Development of processing procedures for advanced silicon solar cells. [antireflection coatings and short circuit currents

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1975-01-01

    Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing.

  7. Optimized 2D array of thin silicon pillars for efficient antireflective coatings in the visible spectrum.

    PubMed

    Proust, Julien; Fehrembach, Anne-Laure; Bedu, Frédéric; Ozerov, Igor; Bonod, Nicolas

    2016-01-01

    Light reflection occuring at the surface of silicon wafers is drastically diminished by etching square pillars of height 110 nm and width 140 nm separated by a 100 nm gap distance in a square lattice. The design of the nanostructure is optimized to widen the spectral tolerance of the antireflective coatings over the visible spectrum for both fundamental polarizations. Angle and polarized resolved optical measurements report a light reflection remaining under 5% when averaged in the visible spectrum for both polarizations in a wide angular range. Light reflection remains almost insensitive to the light polarization even in oblique incidence. PMID:27109643

  8. Millimeter-wave broadband antireflection coatings using laser ablation of subwavelength structures

    NASA Astrophysics Data System (ADS)

    Matsumura, Tomotake; Young, Karl; Wen, Qi; Hanany, Shaul; Ishino, Hirokazu; Inoue, Yuki; Hazumi, Masashi; Koch, Jürgen; Suttman, Oliver; Schütz, Viktor

    2016-05-01

    We report on the first use of laser ablation to make sub-millimeter, broad-band, anti-reflection coatings (ARC) based on sub-wavelength structures (SWS) on alumina and sapphire. We used a 515 nm laser to produce pyramid-shaped structures with pitch of about 320 $\\mu$m and total height of near 800 $\\mu$m. Transmission measurements between 70 and 140 GHz are in agreement with simulations using electromagnetic propagation software. The simulations indicate that SWS ARC with the fabricated shape should have a fractional bandwidth response of $\\Delta \

  9. Optimization of hybrid antireflection structure integrating surface texturing and multi-layer interference coating

    NASA Astrophysics Data System (ADS)

    Kubota, Shigeru; Kanomata, Kensaku; Suzuki, Takahiko; Hirose, Fumihiko

    2014-10-01

    The antireflection structure (ARS) for solar cells is categorized to mainly two different techniques, i.e., the surface texturing and the single or multi-layer antireflection interference coating. In this study, we propose a novel hybrid ARS, which integrates moth eye texturing and multi-layer coat, for application to organic photovoltaics (OPVs). Using optical simulations based on the finite-difference time-domain (FDTD) method, we conduct nearly global optimization of the geometric parameters characterizing the hybrid ARS. The proposed optimization algorithm consists of two steps: in the first step, we optimize the period and height of moth eye array, in the absence of multi-layer coating. In the second step, we optimize the whole structure of hybrid ARS by using the solution obtained by the first step as the starting search point. The methods of the simple grid search and the Hooke and Jeeves pattern search are used for global and local searches, respectively. In addition, we study the effects of deviations in the geometric parameters of hybrid ARS from their optimized values. The design concept of hybrid ARS is highly beneficial for broadband light trapping in OPVs.

  10. Anti-Reflective Coatings R&D for Next Generation Neutrinoless Double Beta Experiments

    NASA Astrophysics Data System (ADS)

    Leder, Alexander; Cuore Collaboration

    2016-03-01

    The Cyogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic source=detector experiment designed to search for the Neutrinoless Double Beta Decay (0 νββ) of 130Te. CUORE currently utilizes a single phonon readout channel per crystal; adding a second channel for scintillation or Cherenkov light would improve particle identification for actively rejecting background events. This light would be collected via semiconductor wafers covered with anti-reflective coatings. These coatings maximize light absorption. In this talk, I will discuss the coating optimization regarding material and structure, and its implications for designing the next generation CUORE-style experiment. In addition, I will discuss projections for possible sensitivities of next generation 0 νββ searches that use dual channel light-phonon readouts.

  11. Broadband Plasma-Sprayed Anti-reflection Coating for Millimeter-Wave Astrophysics Experiments

    NASA Astrophysics Data System (ADS)

    Jeong, O.; Lee, A.; Raum, C.; Suzuki, A.

    2016-08-01

    We have developed a plasma-sprayed anti-reflection (AR) coating technology for millimeter-wave astrophysics experiments with cryogenic optics which achieves minimal dissipative loss and broad bandwidth and is easily and accurately applied. Plasma spraying is a coating process through which melted or heated materials are sprayed onto a substrate. The dielectric constants of the plasma-sprayed coatings were tuned between 2.7 and 7.9 by mixing hollow ceramic microspheres with alumina powder as the base material and varying the plasma energy of the spray. By spraying low loss ceramic materials with a tunable dielectric constant, we can apply multiple layers of AR coating for broadband millimeter-wave detection. At 300 K, we achieved a fractional bandwidth of 106 over 90% transmission using a three-layer AR coating. Applying ceramic coatings on ceramic lenses offers an additional benefit of preventing cryogenic delamination of the coatings. We report on methodology of coating application and measurement of uniformity, repeatability, transmission property, and cryogenic adhesion performance.

  12. Solgel derived tantalum pentoxide films as ultraviolet antireflective coatings for silicon.

    PubMed

    Rehg, T J; Ochoa-Tapia, J A; Knoesen, A; Higgins, B G

    1989-12-15

    A solgel process is described to produce Ta(2)O(5) films as short wavelength antireflective (AR) coatings for silicon. The AR coatings were optimized for 370 nm by controlling the acid catalyzed hydrolysis of Ta(OC(2)H(5))(5), the spin coating parameters, and the heat treatment process (rapid thermal processing (RTP) and muffle furnace). Film thickness uniformity across the wafer was better than 1%, and all the coatings tested passed the standard scotch tape test before and after heat treatment and exhibited no change in optical properties after submersion in liquid N(2). Several heat treatment protocols for densifying the films were studied. Spin coated films heat treated in a muffle furnace at 275 degrees C yielded Ta(2)O(5) AR coatings that reduced the reflectance losses from silicon at 370 nm by 86%, the reduction being within 1% of the theoretical value. Films subjected to RTP at temperatures ranging from 300 to 1000 degrees C reduced the reflectance loss in some cases by as much as 95%. The results demonstrate that spin coated solgel derived Ta(2)O(5) films subjected to a low temperature (<300 degrees C) heat treatment can form durable films suitable for near UV AR coatings for high index silicon devices, such as charge couple imagers and photovoltaic cells. PMID:20556030

  13. Broadband Plasma-Sprayed Anti-reflection Coating for Millimeter-Wave Astrophysics Experiments

    NASA Astrophysics Data System (ADS)

    Jeong, O.; Lee, A.; Raum, C.; Suzuki, A.

    2016-02-01

    We have developed a plasma-sprayed anti-reflection (AR) coating technology for millimeter-wave astrophysics experiments with cryogenic optics which achieves minimal dissipative loss and broad bandwidth and is easily and accurately applied. Plasma spraying is a coating process through which melted or heated materials are sprayed onto a substrate. The dielectric constants of the plasma-sprayed coatings were tuned between 2.7 and 7.9 by mixing hollow ceramic microspheres with alumina powder as the base material and varying the plasma energy of the spray. By spraying low loss ceramic materials with a tunable dielectric constant, we can apply multiple layers of AR coating for broadband millimeter-wave detection. At 300 K, we achieved a fractional bandwidth of 106 over 90% transmission using a three-layer AR coating. Applying ceramic coatings on ceramic lenses offers an additional benefit of preventing cryogenic delamination of the coatings. We report on methodology of coating application and measurement of uniformity, repeatability, transmission property, and cryogenic adhesion performance.

  14. Characterization of Silicon Moth-Eye Antireflection Coatings for Astronomical Applications in the Infrared

    NASA Astrophysics Data System (ADS)

    Jeram, Sarik; Ge, Jian; Jiang, Peng; Phillips, Blayne

    2016-01-01

    Silicon moth-eye antireflective structures have emerged to be an excellent approachfor reducing the amount of light that is lost upon incidence on a given surface of optics made of silicon. This property has been exploited for a wide variety of products ranging from eyeglasses and flat-panel displays to solar panels. These materials typically come in the form of coatings that are applied to an optical substrate such as glass. Moth-eye coatings, made of a periodic array of subwavelength pillars on silicon substrates or other substrates, can produce the desired antireflection (AR) performance for a broad wavelength range and over a wide range of incident angles. In the field of astronomy, every photon striking a detector is significant - and thus, losses from reflectivity at the various optical interfaces before a detector can have significant implications to the science at hand. Moth-eye AR coatings on these optical interfaces may minimize their reflection losses while maximizing light throughput for a multitude of different astronomical instruments. In addition, moth-eye AR coatings, which are patterned directly on silicon surfaces, can significantly enhance the coating durability. At the University of Florida, we tested two moth-eye filters designed for use in the near-infrared regime at 1-8 microns by examining their optical properties, such as transmission, the scattered light, and wavefront quality, and testing the coatings at cryogenic temperatures to characterize their viability for use in both ground- and space-based infrared instruments. This presentation will report our lab evaluation results.

  15. Advancements in organic antireflective coatings for dual-damascene processes

    NASA Astrophysics Data System (ADS)

    Deshpande, Shreeram V.; Shao, Xie; Lamb, James E., III; Brakensiek, Nickolas L.; Johnson, Joe; Wu, Xiaoming; Xu, Gu; Simmons, William J.

    2000-06-01

    Dual Damascene (DD) process has been implemented in manufacturing semiconductor devices with smaller feature sizes (coating (BARC) is used, then the resist thickness variations are minimized thus enhancing the resolution and CD control in trench patterning. Via fill organic BARC materials can also act as etch blocks at the base of the via to protect the substrate from over etch. In this paper we review the important role of via fill organic BARCs in improving the efficiency of via first DD process now being implemented in semiconductor manufacturing.

  16. Conducting antireflection coatings with low polarization dependent loss for telecommunication applications.

    PubMed

    Dobrowolski, J; Ford, Joseph; Sullivan, Brian; Lu, Liping; Osborne, Norman

    2004-12-13

    Conducting optical coatings for the visible light range are commonly made of Indium Tin Oxide (ITO), but ITO is unsuitable for near-infrared telecommunications wavelengths because it can become absorptive after extended illumination. In this paper we show an alternative approach which uses conventional coating materials to create either non-conducting or conducting antireflection (AR) coatings that are effective over a fairly broad spectral region ( lambdalong/lambdashort approximately 1.40) and also usable for a wide range of angles of incidence (0-38 masculine, or 0-55 masculine) in the telecom wavelength range. Not only is the transmittance of windows treated with such coatings quite high, but they can be made to have extreme polarization independence (low polarization dependent loss values). A number of such coating designs are presented in the paper. A prototype of one of the conducting AR coating designs was fabricated and the measurements were found to be in reasonable agreement with the calculated performance. Such AR coatings should be of interest for telecommunication applications and especially for anti-static hermetic packaging of MEMS devices such as optical switches. PMID:19488272

  17. Anti-Reflective Coating On Borosilicate Long Tubes Industrial Process And Quality Control

    NASA Astrophysics Data System (ADS)

    Eisenberg, N.; Ben-Dor, Y.; Warschawski, J. P.

    1989-07-01

    It has been shown that in order to improve the optical efficiency of a solar trough evacuated pipe used for Luz solar electricity generating systems, an appropriate low cost anti-reflective coating process should be implemented in the solar collector production line, and that a dip process is the optimal choice for this application. It is shown in this paper that pumping the coating solution out of the coating container rather than withdrawing the tubes is the most appropriate coating process for Luz's needs. The same method was employed for the second coating solution which was used both for mechanical abrasion resistance improvement and for increasing optical transmissivity. The measuring procedure for quality insurance of the coated tube was investigated thoroughly and an "in-house" technique, including solar simulation and spiral movement of the tested tube, was chosen in preference to the other standard procedures (spectrophotometry, reflectometry). The complete AR coating facility and production procedure is described and the results of the industrial process are analyzed.

  18. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    NASA Astrophysics Data System (ADS)

    Fang, H. S.; Qiu, S. R.; Zheng, L. L.; Schaffers, K. I.; Tassano, J. B.; Caird, J. A.; Zhang, H.

    2008-08-01

    Yb:S-FAP [Yb 3+:Sr 5(PO 4) 3F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF 2-rich melts often encounters cracks during the post-growth cool-down stage. To suppress cracking during cool-down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool-down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented, which produced high-quality, crack-free Yb:S-FAP crystals.

  19. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    SciTech Connect

    Fang, H; Qiu, S; Kheng, L; Schaffers, K; Tassano, J; Caird, J; Zhang, H

    2007-08-20

    Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF{sub 2}-rich melts often encounter cracks during the post growth cool down stage. To suppress cracking during cool down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented and produced high quality, crack-free Yb:S-FAP crystals.

  20. An In-House Thermal Evaporation System for Anti-Reflection An In-House Thermal Evaporation System for Anti-Reflection Coating of Laser Diodes

    NASA Astrophysics Data System (ADS)

    Nagel, Sarah; Nguyen, Duong; Killian, Thomas; Hulet, Randall

    2006-05-01

    Laser diodes have become a very popular and powerful tool in AMO research due to their frequency tunability, small size and low cost. These devices are often used in external cavity diode lasers (ECDL) and injection locked amplifers. In both cases, in order to maintain frequency stability, the reflectivity of the diode facet must be as low as possible. Anti-reflection coating these devices is a commerically available, but rather expensive, procedure. In this poster, we present an in-house thermal evaporation system designed for coating diode lasers with SiO in a vacuum chamber capable of reaching 10-5 torr. We monitor the coating process by measuing the threshold current of the laser diode in-situ. We present reflectivity and coating stability results.

  1. Novel conformal organic antireflective coatings for advanced I-line lithography

    NASA Astrophysics Data System (ADS)

    Deshpande, Shreeram V.; Nowak, Kelly A.; Fowler, Shelly; Williams, Paul; Arjona, Mikko

    2001-08-01

    Flash memory chips are playing a critical role in semiconductor devices due to increased popularity of hand held electronic communication devices such as cell phones and PDAs (personal Digital Assistants). Flash memory offers two primary advantages in semiconductor devices. First, it offers flexibility of in-circuit programming capability to reduce the loss from programming errors and to significantly reduce commercialization time to market for new devices. Second, flash memory has a double density memory capability through stacked gate structures which increases the memory capability and thus saves significantly on chip real estate. However, due to stacked gate structures the requirements for manufacturing of flash memory devices are significantly different from traditional memory devices. Stacked gate structures also offer unique challenges to lithographic patterning materials such as Bottom Anti-Reflective Coating (BARC) compositions used to achieve CD control and to minimize standing wave effect in photolithography. To be applicable in flash memory manufacturing a BARC should form a conformal coating on high topography of stacked gate features as well as provide the normal anti-reflection properties for CD control. In this paper we report on a new highly conformal advanced i-line BARC for use in design and manufacture of flash memory devices. Conformal BARCs being significantly thinner in trenches than the planarizing BARCs offer the advantage of reducing BARC overetch and thus minimizing resist thickness loss.

  2. Low-cost and broadband terahertz antireflection coatings based on DMSO-doped PEDOT/PSS.

    PubMed

    Yan, Fei; Parrott, Edward P J; Liu, Xu Dong; Pickwell-MacPherson, Emma

    2015-06-15

    We report the potential application of 6% dimethylsulfoxide (DMSO)-doped poly (3, 4-ethylenedioxythiophene)/poly (4-styrenesulfonate) (PEDOT/PSS) as a low cost and broadband terahertz (THz) antireflection coating based on the impedance matching effect. The reflected pulses from the quartz and silicon substrates are observed to change with the thickness of the PEDOT/PSS layer. Theoretical analysis based on an equivalent transmission line circuit model and FDTD computational simulations have been used to understand the experimental results. Excellent impedance matching is achieved by a ∼39-nm-thick 6% DMSO-doped PEDOT/PSS layer on quartz, and a ∼101-nm-thick 6% DMSO-doped PEDOT/PSS layer on silicon due to the almost-frequency-independent conductivity of the thin film between 0.3 and 2.5 THz. In the critical conditions, the normalized main pulse transmission remains as high as 74% and 64%, for the quartz and silicon substrates, respectively, significantly higher than the existing state of the art THz antireflection coatings. PMID:26076287

  3. Surface structured optical coatings with near-perfect broadband and wide-angle antireflective properties.

    PubMed

    Perl, Emmett E; McMahon, William E; Farrell, Robert M; DenBaars, Steven P; Speck, James S; Bowers, John E

    2014-10-01

    Optical thin-film coatings are typically limited to designs where the refractive index varies in only a single dimension. However, additional control over the propagation of incoming light is possible by structuring the other two dimensions. In this work, we demonstrate a three-dimensional surface structured optical coating that combines the principles of thin-film optical design with bio-inspired nanostructures to yield near-perfect antireflection. Using this hybrid approach, we attain average reflection losses of 0.2% on sapphire and 0.6% on gallium nitride for 300-1800 nm light. This performance is maintained to very wide incidence angles, achieving less than 1% reflection at all measured wavelengths out to 45° for sapphire. This hybrid design has the potential to significantly enhance the broadband and wide-angle properties for a number of optical systems that require high transparency. PMID:25238041

  4. New artificial dielectric metamaterial and its application as a terahertz antireflection coating.

    PubMed

    Zhang, J; Ade, P A R; Mauskopf, P; Moncelsi, L; Savini, G; Whitehouse, N

    2009-12-10

    We describe a novel artificial dielectric material that has applications at millimeter and submillimeter wavelengths. The material is manufactured from layers of metal mesh patterned onto thin polypropylene sheets, which are then bonded together using a hot pressing process to provide planar rugged discs that can be reliably cycled to cryogenic temperatures. The refractive index of this material can be tuned by adjusting the geometry and spacing of the metal mesh layers. We demonstrate its usage by designing and characterizing a broadband antireflection coating for a Z-cut crystalline quartz plate. The coating was fabricated and applied to the quartz using the hot press technique and characterized using a Fourier transform spectrometer. The performance is shown to be in good agreement with a high frequency structure simulator and transmission line modeling results. PMID:20011003

  5. Recovery Act: A Low Cost Spray Deposited Solar PV Anti-Reflection Coating Final Technical Report

    SciTech Connect

    Harvey, Michael D.

    2010-08-30

    PV module glass is typically low iron glass which exhibits extremely low absorption of light at solar wavelengths. However, reflection losses from typical high quality solar glass are about 4.5% of the input solar energy. By applying an antireflection coating to the cover glass of their modules, a PV module maker will gain at least a 3% increase in the light passing through the glass and being converted to electricity. Thus achieving an increase of >3% in electricity output from the modules. This Project focussed on developing a process that deposits a layer of porous silica (SiO2) on glass or plastic components, and testing the necessary subcomponents and subsystems required to demonstrate the commercial technology. This porous layer acts as a broadband single layer AR coating for glass and plastics, with the added benefit of being a hydrophilic surface for low surface soiling.

  6. An anti-reflection coating for use with PMMA at 193 nm

    NASA Technical Reports Server (NTRS)

    Yen, Anthony; Smith, Henry I.; Schattenburg, M. L.; Taylor, Gary N.

    1992-01-01

    An antireflection coating (ARC) for use with poly(methyl methacrylate) (PMMA) resist for ArF excimer laser lithography (193 nm) was formulated. It consists of PMMA and a bis-azide, 4.4-prime-diazidodiphenyl sulfone (DDS) which crosslinks the film after deep UV (260 nm) irradiation and subsequent annealing. The reacted DDS then serves as the absorber for the 193 nm radiation and also prevents mixing of the ARC and PMMA during PMMA spin-coating and development. The effectiveness of the ARC was demonstrated by exposing, in PMMA, using achromatic holographic lithography, gratings of 100 nm period (about 50 nm linewidth) that are almost entirely free of an orthogonal standing wave.

  7. Diamondlike carbon as a moisture barrier and antireflecting coating on optical materials

    NASA Technical Reports Server (NTRS)

    Woollam, John A.; De, Bhola N.; Chen, L. Y.; Pouch, John J.; Alterovitz, Samuel A.

    1990-01-01

    Diamondlike carbon (DLC) is amorphous, hard, semitransparent, and is under consideration for use as a coating material for infrared optics. DLC is also designated as a-C:H to indicate its amorphous nature as well as to indicate the presence of large (20 to 55 percent) amounts of hydrogen in the film. Two important questions arise with respect to use of DLC in infrared optics. Will the lack of grain boundaries help to keep moisture from penetrating the film. Secondly, application as an antireflection coating places restrictions on the allowed values of the index of refraction of the film relative to the particular substrate material being used. Will DLC have the correct index range. These two questions are addressed in this paper.

  8. An anti-reflection coating for use with PMMA at 193 nm

    NASA Astrophysics Data System (ADS)

    Yen, Anthony; Smith, Henry I.; Schattenburg, M. L.; Taylor, Gary N.

    1992-02-01

    An antireflection coating (ARC) for use with poly(methyl methacrylate) (PMMA) resist for ArF excimer laser lithography (193 nm) was formulated. It consists of PMMA and a bis-azide, 4.4-prime-diazidodiphenyl sulfone (DDS) which crosslinks the film after deep UV (260 nm) irradiation and subsequent annealing. The reacted DDS then serves as the absorber for the 193 nm radiation and also prevents mixing of the ARC and PMMA during PMMA spin-coating and development. The effectiveness of the ARC was demonstrated by exposing, in PMMA, using achromatic holographic lithography, gratings of 100 nm period (about 50 nm linewidth) that are almost entirely free of an orthogonal standing wave.

  9. Large-aperture wide-bandwidth antireflection-coated silicon lenses for millimeter wavelengths.

    PubMed

    Datta, R; Munson, C D; Niemack, M D; McMahon, J J; Britton, J; Wollack, E J; Beall, J; Devlin, M J; Fowler, J; Gallardo, P; Hubmayr, J; Irwin, K; Newburgh, L; Nibarger, J P; Page, L; Quijada, M A; Schmitt, B L; Staggs, S T; Thornton, R; Zhang, L

    2013-12-20

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n=3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30° with low cross polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth. PMID:24513939

  10. Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, Manuel A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n 3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating.We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30deg with low cross polarization.We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  11. Recent developments in highly durable protective/antireflection coatings for Ge and ZnS substrates

    NASA Astrophysics Data System (ADS)

    Hasan, Wasim; Propst, Steven H.

    1994-11-01

    Antireflection coated ZnS and Ge substrates erode under severe operational environmental conditions. High velocity water drop impact and high velocity sand particle impact are primarily military concerns that originated with the advent of faster aircraft. High speed flight through rain and sand storms seriously erodes forward facing components such as infrared transmitting windows and/or domes. This erosion of windows and/or domes causes reduction in transmission, resulting in the reduction of detection and recognition sensitivity of the electro-optical sensor. A single film of one quarterwave thick hard-carbon coating has been used on germanium to increase optical transmission (reducing Fresnel's reflection losses on Ge surface) as well as to reduce rain and sand impact damage to some extent, at a lower speed. At high speed, the damage becomes more severe, resulting in unacceptable large transmission losses. Recently, new hard carbon coatings have been developed for Ge which have substantially increased the damage threshold of the coated substrates. The rain erosion test was performed at Wright-Patterson AFB facility in Dayton, Ohio, and the sand tests were performed at PDA Engineering in Santa Ana, California. In addition, a multilayer AR coating utilizing hard carbon film as one of the low index films has also been developed at Hughes for ZnS substrates. The optical properties, rain erosion, sand erosion, and sand abrasion test results of these coatings are also presented in this paper.

  12. Anti-Reflective and Waterproof Hard Coating for High Power Laser Optical Elements

    NASA Astrophysics Data System (ADS)

    Murahara, Masataka; Yabe, Takashi; Uchida, Shigeaki; Yoshida, Kunio; Okamoto, Yoshiaki

    2006-05-01

    A hard coating method of single crystalline porous silica film is widely used for high power laser optical elements in the air. However, there is no protective hard coating method for the elements to survive high power laser irradiance while in the water. We, thus, developed a new method for a waterproof coating with photo-oxidation of silicone oil. The silicone oil was spin-coated onto the surface of optical elements, and then irradiated with a xenon excimer lamp in the air. In this treatment, a protective coating for plastic lenses, mirrors, and nonlinear optical crystals, which are highly deliquescent, was developed by taking advantage of the phenomenon in which organic silicone oil is transformed to inorganic amorphous glass by a process of photo-oxidation. This technique has enabled an optical thin coating film to transmit ultraviolet rays of wavelengths under 200 nm and possess the characteristics of homogeneity, high density, resistance to environment, anti-reflectiveness, resistance to water, and Mohs' scale of 5, which is comparable to apatite. This allows us to cool a slab laser head and use as a mirror for underwater laser welding.

  13. Monolithic graded-refractive-index glass-based antireflective coatings. Broadband/omnidirectional light harvesting and self-cleaning characteristics

    SciTech Connect

    Aytug, Tolga; Lupini, Andrew R.; Jellison, Gerald E.; Joshi, Pooran C.; Ivanov, Ilia H.; Liu, Tao; Wang, Peng; Menon, Rajesh; Trejo, Rosa M.; Lara-Curzio, Edgar; Hunter, Scott R.; Simpson, John T.; Paranthaman, M. Parans; Christen, David K.

    2015-04-23

    The design of multifunctional coatings impact impact the performance of many optical systems and components. Such coatings should be mechanically robust, and combine user-defined optical and wetting functions with scalable fabrication formulations. By taking cues from the properties of some natural biological structures, we report here the formation of low-refractive index antireflective glass films that embody omni-directional optical properties over a wide range of wavelengths, while also possessing specific wetting capabilities. The coatings comprise an interconnected network of nanoscale pores surrounded by a nanostructured silica framework. These structures result from a novel fabrication method that utilizes metastable spinodal phase separation in glass-based materials. The approach not only enables design of surface microstructures with graded-index antireflection characteristics, where the surface reflection is suppressed through optical impedance matching between interfaces, but also facilitates self-cleaning ability through modification of the surface chemistry. Based on near complete elimination of Fresnel reflections (yielding >95% transmission through a single-side coated glass) and corresponding increase in broadband transmission, the fabricated nanostructured surfaces are found to promote a general and an invaluable ~3–7% relative increase in current output of multiple direct/indirect bandgap photovoltaic cells. Moreover, these antireflective surfaces also demonstrate superior resistance against mechanical wear and abrasion. Unlike conventional counterparts, the present antireflective coatings are essentially monolithic, enabling simultaneous realization of graded index anti-reflectivity, self-cleaning capability, and mechanical stability within the same surface. Moreover, the concept represents a fundamental basis for development of advanced coated optical quality products, especially where environmental exposure is required.

  14. Monolithic graded-refractive-index glass-based antireflective coatings. Broadband/omnidirectional light harvesting and self-cleaning characteristics

    DOE PAGESBeta

    Aytug, Tolga; Lupini, Andrew R.; Jellison, Gerald E.; Joshi, Pooran C.; Ivanov, Ilia H.; Liu, Tao; Wang, Peng; Menon, Rajesh; Trejo, Rosa M.; Lara-Curzio, Edgar; et al

    2015-04-23

    The design of multifunctional coatings impact impact the performance of many optical systems and components. Such coatings should be mechanically robust, and combine user-defined optical and wetting functions with scalable fabrication formulations. By taking cues from the properties of some natural biological structures, we report here the formation of low-refractive index antireflective glass films that embody omni-directional optical properties over a wide range of wavelengths, while also possessing specific wetting capabilities. The coatings comprise an interconnected network of nanoscale pores surrounded by a nanostructured silica framework. These structures result from a novel fabrication method that utilizes metastable spinodal phase separationmore » in glass-based materials. The approach not only enables design of surface microstructures with graded-index antireflection characteristics, where the surface reflection is suppressed through optical impedance matching between interfaces, but also facilitates self-cleaning ability through modification of the surface chemistry. Based on near complete elimination of Fresnel reflections (yielding >95% transmission through a single-side coated glass) and corresponding increase in broadband transmission, the fabricated nanostructured surfaces are found to promote a general and an invaluable ~3–7% relative increase in current output of multiple direct/indirect bandgap photovoltaic cells. Moreover, these antireflective surfaces also demonstrate superior resistance against mechanical wear and abrasion. Unlike conventional counterparts, the present antireflective coatings are essentially monolithic, enabling simultaneous realization of graded index anti-reflectivity, self-cleaning capability, and mechanical stability within the same surface. Moreover, the concept represents a fundamental basis for development of advanced coated optical quality products, especially where environmental exposure is required.« less

  15. Broadband durable antireflection coating for an E-O system window having multiple-wavelength applications

    NASA Astrophysics Data System (ADS)

    Hasan, Wasim; Bui, Hoa T.

    1992-12-01

    Conventional ZnS, clear ZnS, ZnSe, and ZnS/ZnSe sandwich materials along with 8 to 12 micrometers anti-reflection (AR) coatings have been used as windows for forward looking infrared (FLIR) thermal imaging electro-optical sensors (such as those incorporated on PAVE TACK, F-18, and LANTIRN pods). Conventional ZnS also has been used as dome material for IR Maverick missiles and other missile applications. All of these systems have separate windows/systems for target designation, rangefinding, and low light level television (LLLTV) applications. New generation system require that a single window provide multispectral capabilities to perform various functions. A graded index AR coating developed at Hughes Danbury Optical Systems (HDOS) provides the multispectral capabilities and is highly durable for subsonic aircraft and missile applications. The spectral performance, durability, rain- erosion, and some sand and dust data of such a coating are presented in this paper. The data is also presented for this coating in conjunction with grids for EMI attenuation. The transmission of the coating as a function angle of incidence is also presented.

  16. The Broadband Anti-reflection Coated Extended Hemispherical Silicon Lenses for uc(Polarbear-2) Experiment

    NASA Astrophysics Data System (ADS)

    Siritanasak, P.; Aleman, C.; Arnold, K.; Cukierman, A.; Hazumi, M.; Kazemzadeh, K.; Keating, B.; Matsumura, T.; Lee, A. T.; Lee, C.; Quealy, E.; Rosen, D.; Stebor, N.; Suzuki, A.

    2015-12-01

    uc(Polarbear-2) (PB-2) is a next-generation receiver that is part of the Simons Array cosmic microwave background (CMB) polarization experiment which is located in the Atacama desert in Northern Chile. The primary scientific goals of the Simons Array are a deep search for the CMB B-mode signature of gravitational waves from inflation and the characterization of large-scale structure using its effect on CMB polarization. The PB-2 receiver will deploy with 1897 dual-polarization sinuous antenna-coupled pixels, each with a directly contacting extended hemispherical silicon lens. Every pixel has dual polarization sensitivity in two spectral bands centered at 95 and 150 GHz, for a total of 7588 transition edge sensor bolometers operating at 270 mK. To achieve the PB-2 detector requirements, we developed a broadband anti-reflection (AR) coating for the extended hemispherical lenses that uses two molds to apply two layers of epoxy, Stycast 1090 and Stycast 2850FT. Our measurements of the absorption loss from the AR coating on a flat surface at cryogenic temperatures show less than 1 % absorption, and the coating has survived multiple thermal cycles. We can control the diameter of the coating within 25 \\upmu m and translation errors are within 25 \\upmu m in all directions, which results in less than 1 % decrease in transmittance. We also find the performance of the AR-coated lens matches very well with simulations.

  17. Comparisons between laser damage and optical electric field behaviors for hafnia/silica antireflection coatings

    SciTech Connect

    Bellum, John; Kletecka, Damon; Rambo, Patrick; Smith, Ian; Schwarz, Jens; Atherton, Briggs

    2011-03-20

    We compare designs and laser-induced damage thresholds (LIDTs) of hafnia/silica antireflection (AR) coatings for 1054 nm or dual 527 nm/1054 nm wavelengths and 0 deg. to 45 deg. angles of incidence (AOIs). For a 527 nm/1054 nm, 0 deg. AOI AR coating, LIDTs from three runs arbitrarily selected over three years are {approx}20 J/cm{sup 2} or higher at 1054 nm and <10 J/cm{sup 2} at 527 nm. Calculated optical electric field intensities within the coating show two intensity peaks for 527 nm but not for 1054 nm, correlating with the lower (higher) LIDTs at 527 nm (1054 nm). For 1054 nm AR coatings at 45 deg. and 32 deg. AOIs and S and P polarizations (Spol and Ppol), LIDTs are high for Spol (>35 J/cm{sup 2}) but not as high for Ppol (>30 J/cm{sup 2} at 32 deg. AOI; {approx}15 J/cm{sup 2} at 45 deg. AOI). Field intensities show that Ppol discontinuities at media interfaces correlate with the lower Ppol LIDTs at these AOIs. For Side 1 and Side 2 dual 527 nm/1054 nm AR coatings of a diagnostic beam splitter at 22.5 deg. AOI, Spol and Ppol LIDTs (>10 J/cm{sup 2} at 527 nm; >35 J/cm{sup 2} at 1054 nm) are consistent with Spol and Ppol intensity behaviors.

  18. Evaporation of uniform antireflection coatings on hemispherical lenses to enhance infrared antenna gain

    NASA Astrophysics Data System (ADS)

    Slovick, Brian A.; Krenz, Peter M.; Zummo, Guy; Boreman, Glenn D.

    2010-03-01

    Infrared dipole-coupled bolometers receive radiation more efficiently when illuminated through a high permittivity, antireflection (AR) coated, hemispherical immersion lens. To maintain the enhanced responsivity for all illumination angles, the AR coating must be uniform over the hemispherical surface. An evaporation method for depositing a uniform AR coating on the hemispherical surface is presented. The lens is tilted relative to the source, which can be either electron-beam or thermal, and rotated throughout the deposition. Evaporation at an angle of 70° yields a uniform film with less than 10% thickness variation over a 120° full angle of the hemispherical surface. A theoretical model is developed and compared to profilometer measurements. In all cases, there is general agreement between theory and measurement. A single dipole is fabricated onto the flat surface of an AR-coated germanium immersion lens and the responsivity is measured for both substrate-side and air-side illumination. With a zinc sulfide (ZnS) single-layer AR coating, substrate-side illumination yields a broadside antenna response 49 ± 2.7 times greater than air-side illumination.

  19. The Broadband Anti-reflection Coated Extended Hemispherical Silicon Lenses for Polarbear-2 Experiment

    NASA Astrophysics Data System (ADS)

    Siritanasak, P.; Aleman, C.; Arnold, K.; Cukierman, A.; Hazumi, M.; Kazemzadeh, K.; Keating, B.; Matsumura, T.; Lee, A. T.; Lee, C.; Quealy, E.; Rosen, D.; Stebor, N.; Suzuki, A.

    2016-08-01

    Polarbear-2 (PB-2) is a next-generation receiver that is part of the Simons Array cosmic microwave background (CMB) polarization experiment which is located in the Atacama desert in Northern Chile. The primary scientific goals of the Simons Array are a deep search for the CMB B-mode signature of gravitational waves from inflation and the characterization of large-scale structure using its effect on CMB polarization. The PB-2 receiver will deploy with 1897 dual-polarization sinuous antenna-coupled pixels, each with a directly contacting extended hemispherical silicon lens. Every pixel has dual polarization sensitivity in two spectral bands centered at 95 and 150 GHz, for a total of 7588 transition edge sensor bolometers operating at 270 mK. To achieve the PB-2 detector requirements, we developed a broadband anti-reflection (AR) coating for the extended hemispherical lenses that uses two molds to apply two layers of epoxy, Stycast 1090 and Stycast 2850FT. Our measurements of the absorption loss from the AR coating on a flat surface at cryogenic temperatures show less than 1 % absorption, and the coating has survived multiple thermal cycles. We can control the diameter of the coating within 25 {\\upmu }m and translation errors are within 25 {\\upmu }m in all directions, which results in less than 1 % decrease in transmittance. We also find the performance of the AR-coated lens matches very well with simulations.

  20. An experimental study of antireflective coatings in Ge light detectors for scintillating bolometers

    NASA Astrophysics Data System (ADS)

    Mancuso, M.; Beeman, J. W.; Giuliani, A.; Dumoulin, L.; Olivieri, E.; Pessina, G.; Plantevin, O.; Rusconi, C.; Tenconi, M.

    2014-01-01

    Luminescent bolometers are double-readout devices able to measure simultaneously the phonon and the light yields after a particle interaction in the detector. This operation allows in some cases to tag the type of the interacting quantum, crucial issue for background control in rare event experiments such as the search for neutrinoless double beta decay and for interactions of particle dark matter candidates. The light detectors used in the LUCIFER and LUMINEU searches (projects aiming at the study of the double beta interesting candidates 82Se and 100Mo using ZnSe and ZnMoO4 scintillating bolometers) consist of hyper-pure Ge thin slabs equipped with NTD thermistors. A substantial sensitivity improvement of the Ge light detectors can be obtained applying a proper anti-reflective coatings on the Ge side exposed to the luminescent bolometer. The present paper deals with the investigation of this aspect, proving and quantifying the positive effect of a SiO2 and a SiO coating and setting the experimental bases for future tests of other coating materials. The results confirm that an appropriate coating procedure helps in improving the sensitivity of bolometric light detectors by an important factor (in the range 20% - 35%) and needs to be included in the recipe for the development of an optimized radio-pure scintillating bolometer.

  1. Titanium dioxide antireflection coating for silicon solar cells by spray deposition

    NASA Technical Reports Server (NTRS)

    Kern, W.; Tracy, E.

    1980-01-01

    A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

  2. Antireflection coatings for deep ultraviolet optics deposited by magnetron sputtering from Al targets.

    PubMed

    Liao, Bo-Huei; Lee, Cheng-Chung

    2011-04-11

    We introduce an innovative technique for the deposition of fluorine doped oxide (F:Al(2)O(3)) films by DC pulse magnetron sputtering from aluminum targets at room temperature. There was almost no change in transmittance even after the film was exposed to air for two weeks. Its refractive index was around 1.69 and the extinction coefficient was smaller than 1.9 × 10(-4) at 193 nm. An AlF(3)/F:Al(2)O(3) antireflection coating was deposited on both sides of a quartz substrate. A high transmittance of 99.32% was attained at the 193 nm wavelength. The cross-sectional morphology showed that the surface of the multilayer films was smooth and there were no columnar or porous structures. PMID:21503058

  3. Highly transparent triboelectric nanogenerator for harvesting water-related energy reinforced by antireflection coating

    NASA Astrophysics Data System (ADS)

    Liang, Qijie; Yan, Xiaoqin; Gu, Yousong; Zhang, Kui; Liang, Mengyuan; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-03-01

    Water-related energy is an inexhaustible and renewable energy resource in our environment, which has huge amount of energy and is not largely dictated by daytime and sunlight. The transparent characteristic plays a key role in practical applications for some devices designed for harvesting water-related energy. In this paper, a highly transparent triboelectric nanogenerator (T-TENG) was designed to harvest the electrostatic energy from flowing water. The instantaneous output power density of the T-TENG is 11.56 mW/m2. Moreover, with the PTFE film acting as an antireflection coating, the maximum transmittance of the fabricated T-TENG is 87.4%, which is larger than that of individual glass substrate. The T-TENG can be integrated with silicon-based solar cell, building glass and car glass, which demonstrates its potential applications for harvesting waste water energy in our living environment and on smart home system and smart car system.

  4. Indium doped zinc oxide nanowire thin films for antireflection and solar absorber coating applications

    SciTech Connect

    Shaik, Ummar Pasha; Krishna, M. Ghanashyam

    2014-04-24

    Indium doped ZnO nanowire thin films were prepared by thermal oxidation of Zn-In metal bilayer films at 500°C. The ZnO:In nanowires are 20-100 nm in diameter and several tens of microns long. X-ray diffraction patterns confirm the formation of oxide and indicate that the films are polycrystalline, both in the as deposited and annealed states. The transmission which is <2% for the as deposited Zn-In films increases to >90% for the ZnO:In nanowire films. Significantly, the reflectance for the as deposited films is < 10% in the region between 200 to 1500 nm and < 2% for the nanowire films. Thus, the as deposited films can be used solar absorber coatings while the nanowire films are useful for antireflection applications. The growth of nanowires by this technique is attractive since it does not involve very high temperatures and the use of catalysts.

  5. Characterization and simulation on antireflective coating of amorphous silicon oxide thin films with gradient refractive index

    NASA Astrophysics Data System (ADS)

    Huang, Lu; Jin, Qi; Qu, Xingling; Jin, Jing; Jiang, Chaochao; Yang, Weiguang; Wang, Linjun; Shi, Weimin

    2016-08-01

    The optical reflective properties of silicon oxide (SixOy) thin films with gradient refractive index are studied both theoretically and experimentally. The thin films are widely used in photovoltaic as antireflective coatings (ARCs). An effective finite difference time domain (FDTD) model is built to find the optimized reflection spectra corresponding to structure of SixOy ARCs with gradient refractive index. Based on the simulation analysis, it shows the variation of reflection spectra with gradient refractive index distribution. The gradient refractive index of SixOy ARCs can be obtained in adjustment of SiH4 to N2O ratio by plasma-enhanced chemical vapor deposition (PECVD) system. The optimized reflection spectra measured by UV-visible spectroscopy confirms to agree well with that simulated by FDTD method.

  6. Laser-induced damage behaviors of antireflective coatings at cryogenic condition.

    PubMed

    Wang, He; Zhang, Weili; He, Hongbo

    2012-12-20

    The laser-induced damage to antireflective coatings on Yb:YAG crystals under different temperatures was investigated. An optical profiler, field-emission scanning-electron microscopy, and a step profiler were used to determine the damage morphology, including size and depth. The results show that there is about 5 J/cm(2) decrease in the laser-induced damage threshold of cryogenic conditions compared to that of room temperature in 1-on-1 test mode, and a 3 J/cm(2) decrease in 100-on-1 mode. There is an accumulation effect in both cases. Meanwhile, the damage areas and depths are also much larger under cryogenic conditions. The precipitation of the subsurface defects in the substrate and the thermal stress in the interface between the film and the substrate under cryogenic conditions are considered to be the key factors in the unique damage behaviors. PMID:23262610

  7. Three-layer antireflection coatings - A new method for design and optimization

    NASA Astrophysics Data System (ADS)

    Nagendra, C. L.; Thutupalli, G. K. M.

    1983-12-01

    An algorithm offering a simpler and faster optimization procedure is developed for the design of multilayer antireflection coatings, and a closed-loop nonlinear approximation technique is used to arrive at the exact thickness of each layer. The method has been used in the design of systems with high- and low-index substrates normally used in IR regions and in visible to near-IR regions, respectively. In a comparative study with other techniques the present design was preferred over Dobrowolski's (1981, 1982) if a wider spectral bandwidth is of more importance than spectral losses. The use of this method permits optimum design with refinement in only one thickness. This non-lambda/4 system gives higher flexibility in choosing the refractive index of the materials and correcting the system in in-situ conditions.

  8. New generation of bottom anti-reflective coatings (BARCs): photodefinable BARCs

    NASA Astrophysics Data System (ADS)

    Guerrero, Douglas J.; Trudgeon, Tonya

    2003-06-01

    Three polymer systems, polycarbonates, polysulfonyl esters, and hybrid carbonate-sulfones, were evaluated as materials for a new generation of bottom anti-reflective coatings (BARCs). The polymers were tested for their solubility in accepted industry solvents, resistance to photoresist solvents after casting, thermal stability, and photosensitivity. From these, polysulfonyl esters show more promising properties as photodefinable BARCs than the other systems because of their good solvent solubility and resistance to photoresist solvents after casting. These polymers can be formulated in ethyl lactate (EL) or 1-methoxy-2-acetoxypropane (PGMEA) but are insoluble in the same solvents after curing above 170°C. The polysulfonyl esters were thermally stable up to ~300°C in air. The cured films were exposed with DUV light at 200 to 600 mJ/cm2. After exposure, the films can be easily removed in alkaline developer.

  9. Millimeter-wave broadband antireflection coatings using laser ablation of subwavelength structures.

    PubMed

    Matsumura, Tomotake; Young, Karl; Wen, Qi; Hanany, Shaul; Ishino, Hirokazu; Inoue, Yuki; Hazumi, Masashi; Koch, Jürgen; Suttman, Oliver; Schütz, Viktor

    2016-05-01

    We report on the first use of laser ablation to make submillimeter, broadband, antireflection coatings (ARCs) based on subwavelength structures (SWSs) on alumina and sapphire. We used a 515 nm laser to produce pyramid-shaped structures with a pitch of about 320 μm and a total height of near 800 μm. Transmission measurements between 70 and 140 GHz are in agreement with simulations using electromagnetic propagation software. The simulations indicate that SWS-ARCs with the fabricated shape should have a fractional bandwidth response of Δν/νcenter=0.55 centered on 235 GHz for which reflections are below 3%. Extension of the bandwidth to both lower and higher frequencies, between a few tens of gigahertz and a few terahertz, should be straightforward with appropriate adjustment of laser ablation parameters. PMID:27140362

  10. Preparation of a Functionally Graded Fluoropolymer Thin Film and Its Application to Antireflective Coating

    NASA Astrophysics Data System (ADS)

    Senda, Kazuo; Matsuda, Tsuyoshi; Kawanishi, Takumi; Tanaka, Kuniaki; Usui, Hiroaki

    2013-05-01

    Fluoropolymer thin films were prepared by the ion-assisted vapor deposition polymerization (IAD) of 2-(perfluorohexyl) ethylacrylate (Rf-6) under Ar ion irradiation. The ion acceleration voltage Va largely affected the film characteristics. With increasing Va, the adhesion strength between the film and the substrate improved, while the surface energy and the refractive index increased. To attain a high adhesion strength, a low surface energy, and a low optical reflectivity simultaneously, a functionally graded film was prepared by varying Va from 300 to 0 V continually in the course of film growth. As a consequence, an antireflective coating with good adhesion and low surface energy was obtained. The optical reflectivity of a glass substrate was reduced from 4.9 to 0.55% at a wavelength of 400 nm by depositing a 100-nm-thick single-layer functionally graded fluoropolymer film. The surface energy of this film was 8.5 mJ/m2.

  11. Optical breathing of nano-porous antireflective coatings through adsorption and desorption of water

    NASA Astrophysics Data System (ADS)

    Nielsen, Karsten H.; Kittel, Thomas; Wondraczek, Katrin; Wondraczek, Lothar

    2014-10-01

    We report on the direct consequences of reversible water adsorption on the optical performance of silica-based nanoporous antireflective (AR) coatings as they are applied on glass in photovoltaic and solar thermal energy conversion systems. In situ UV-VIS transmission spectroscopy and path length measurements through high-resolution interferometric microscopy were conducted on model films during exposure to different levels of humidity and temperature. We show that water adsorption in the pores of the film results in a notable increase of the effective refractive index of the coating. As a consequence, the AR effect is strongly reduced. The temperature regime in which the major part of the water can be driven-out rapidly lies in the range of 55°C and 135°C. Such thermal desorption was found to increase the overall transmission of a coated glass by ~ 1%-point. As the activation energy of isothermal desorption, we find a value of about 18 kJ/mol. Within the experimental range of our data, the sorption and desorption process is fully reversible, resulting in optical breathing of the film. Nanoporous AR films with closed pore structure or high hydrophobicity may be of advantage for maintaining AR performance under air exposure.

  12. Optical breathing of nano-porous antireflective coatings through adsorption and desorption of water.

    PubMed

    Nielsen, Karsten H; Kittel, Thomas; Wondraczek, Katrin; Wondraczek, Lothar

    2014-01-01

    We report on the direct consequences of reversible water adsorption on the optical performance of silica-based nanoporous antireflective (AR) coatings as they are applied on glass in photovoltaic and solar thermal energy conversion systems. In situ UV-VIS transmission spectroscopy and path length measurements through high-resolution interferometric microscopy were conducted on model films during exposure to different levels of humidity and temperature. We show that water adsorption in the pores of the film results in a notable increase of the effective refractive index of the coating. As a consequence, the AR effect is strongly reduced. The temperature regime in which the major part of the water can be driven-out rapidly lies in the range of 55°C and 135°C. Such thermal desorption was found to increase the overall transmission of a coated glass by ~ 1%-point. As the activation energy of isothermal desorption, we find a value of about 18 kJ/mol. Within the experimental range of our data, the sorption and desorption process is fully reversible, resulting in optical breathing of the film. Nanoporous AR films with closed pore structure or high hydrophobicity may be of advantage for maintaining AR performance under air exposure. PMID:25307536

  13. Effect of substrate index of refraction on the design of antireflection coatings

    NASA Astrophysics Data System (ADS)

    Willey, Ronald R.

    2011-09-01

    Formulae to estimate the average percent reflectance (Rave) of a broadband antireflection (AR) coating as a function of the bandwidth (B), the overall thickness (C), the index of refraction of the last layer (L), and the difference between the indices of the high- and low-index layers (D) were reported in 1991. Various refinements of these formulae and other insights into the underlying behavior of such coating designs have been reported up until the present time. Dobrowolski, et al.6 and Tikhonravov, et al.7 have also added independent viewpoints to this subject over this period. In the previous studies, the effects of the index of refraction of the substrate have mostly been ignored and have appeared to be very minor. This study has investigated the influence of the substrate index on the Rave results. It has been found that there seem to be two classes of designs with respect to the effect of substrate index. In the class of "step down" AR designs, there is a significant effect, in the other class, there is no significant effect. Even in the step-down case, there is no effect of substrate index if any and all indices of refraction for the coating materials are available from that of the index of the substrate to the index of the media.

  14. Optical breathing of nano-porous antireflective coatings through adsorption and desorption of water

    PubMed Central

    Nielsen, Karsten H.; Kittel, Thomas; Wondraczek, Katrin; Wondraczek, Lothar

    2014-01-01

    We report on the direct consequences of reversible water adsorption on the optical performance of silica-based nanoporous antireflective (AR) coatings as they are applied on glass in photovoltaic and solar thermal energy conversion systems. In situ UV-VIS transmission spectroscopy and path length measurements through high-resolution interferometric microscopy were conducted on model films during exposure to different levels of humidity and temperature. We show that water adsorption in the pores of the film results in a notable increase of the effective refractive index of the coating. As a consequence, the AR effect is strongly reduced. The temperature regime in which the major part of the water can be driven-out rapidly lies in the range of 55°C and 135°C. Such thermal desorption was found to increase the overall transmission of a coated glass by ~ 1%-point. As the activation energy of isothermal desorption, we find a value of about 18 kJ/mol. Within the experimental range of our data, the sorption and desorption process is fully reversible, resulting in optical breathing of the film. Nanoporous AR films with closed pore structure or high hydrophobicity may be of advantage for maintaining AR performance under air exposure. PMID:25307536

  15. Broadband anti-reflective and water-repellent coatings on glass substrates for self-cleaning photovoltaic cells

    SciTech Connect

    Li, Xiaoyu; He, Junhui; Liu, Weiyi

    2013-07-15

    Graphical abstract: High performance broadband antireflective and water-repellent coatings were fabricated on glass substrates, which can improve the short-circuit current of solar cells as much as 6.6% in comparison with glass substrates without the coatings. - Highlights: • Broadband anti-reflective and water-repellent coatings were fabricated. • Transmittance increased to 99.0%, significantly higher than that of commercial solar glasses. • The performance of standard solar cells with the AR coating was enhanced as much as 6.6%. - Abstract: High performance broadband antireflective (AR) and water-repellent coatings were fabricated on glass substrates by assembly of silica nanoparticles and polyelectrolytes via the layer-by-layer (LbL) assembly technique, followed by calcination and hydrophobic modification. A porous poly(diallyladimethylammonium chloride) (PDDA)/20 nm SiO{sub 2} nanoparticles (S-20) multilayer coating with AR property was prepared first. The maximum transmittance is as high as 99.0%, while that of the glass substrate is only 91.3%. After calcination and hydrophobic modification, the coating became water-repellent while maintaining the good AR property. Such water-repellent AR coatings can improve the short-circuit current of solar cells as much as 6.6% in comparison with glass substrates without the coatings. Scanning electron microscopy (SEM) was used to observe the morphology and thickness of coatings. Transmission spectra and reflection spectra were characterized by UV–vis spectrophotometer. The surface wettability was studied by a contact angle/interface system.

  16. Infrared durable protective/antireflection coatings with high performance on Ge and Si substrates

    NASA Astrophysics Data System (ADS)

    Yao, XiLin; Xiong, ChangXin; Yang, ChangCheng; Tong, NanChun

    2006-02-01

    Firstly, a reverse synthesis method is outlined for the determination of the optical constants of infrared coatings from transmittance spectrum data by optimizing the physical thickness, refractive index and extinction coefficient, which can apply to all kinds of transmission spectra and do not rely on the existence of interference fringe patterns and the absorption of substrates. A lot of deposition experiments with the ion-assisted deposition (IAD) technique have firstly done about infrared optical materials ZnS, YF3, Ge and DLC (diamond-like-carbon), in order to obtain high dense and low absorbance layers in the 3-5μm and 8-12μm spectral windows. Using the reverse synthesis method, the refractive index and extinction coefficient of these materials have been obtained accurately. The appropriate deposition parameters and the problems from the deposition process are in detail discussed in this paper. YF3 has been then associated with ZnS and Ge layers so as to obtain antireflection coatings with high performance on Ge and Si substrates in 3-5μm and/or 8-12μm range. In addition, a novel multi-layer infrared AR coating utilizing DLC film as one of the low index films has also been developed for Si and Ge substrates. The optical performance is satisfied (average transmittance is no less than 97%, maximum transmittance is more than 98%, from 8μm to 11.5μm), which is better than that of a single film of one quarterwave DLC coating with interior surface multi-layer AR coated on Ge substrates. However, the adhesion between multi-layer AR coatings and DLC coating is not well, leading to coatings falling off from substrates after humidity test and moderate abrasion test, according to MIL-F-48497. Through a lot of experiments, a non-absorbing coating material has been found as bonding layer to solve this problem. The optical properties of three kinds of infrared coatings and the environmental and physical durability test results including high/low temperature test

  17. Responsivity enhancement of mid-infrared PbSe detectors using CaF2 nano-structured antireflective coatings

    NASA Astrophysics Data System (ADS)

    Weng, Binbin; Qiu, Jijun; Yuan, Zijian; Larson, Preston R.; Strout, Gregory W.; Shi, Zhisheng

    2014-01-01

    The CaF2 nano-structures grown by thermal vapor deposition are presented. Significant responsivity improvement (>200%) of mid-infrared PbSe detectors incorporating a 200 nm nano-structured CaF2 coating was observed. The detector provides a detectivity of 4.2 × 1010 cm . Hz1/2/W at 3.8 μm, which outperforms all the reported un-cooled PbSe detectors. Structural investigations show that the coating is constructed by tapered-shape nanostructures, which creates a gradient refractive-index profile. Analogy to moth-eye antireflective mechanism, the gradient refractive-index nanostructures play the major roles for this antireflection effect. Some other possible mechanisms that help enhance the device performance are also discussed in the work.

  18. Process development and impurities analysis for the bottom antireflective coating material

    NASA Astrophysics Data System (ADS)

    Ko, Fu-Hsiang; Chen, Hsuen-Li; Huang, Tiao-Yuan; Cheng, Hsu-Chun; Ko, Chu-Jung; Chu, Tieh-Chi

    2001-08-01

    The optical behavior of semiconductor bottom antireflective coating (BARC) material was investigated by both the measurement and simulation methods. The effects of spin- coating rate, interface reflection, BARC layer thickness and photoresist layer thickness were studied. Our results indicated that the 62.5 nm of BARC layer had strong effect on suppressing the light reflection of wavelength of 248 nm form the wafer surface, irrespective of the photoresist layer thickness. Based on the gravimetric method, a high throughput and one-step microwave digestion procedure was developed for the BARC materials. The digestion efficiency increased with the digestion duration and the temperature. By following the established one-step microwave digestion method and inductively coupled plasma mass spectrometry determination, the detection limits obtained for Cr, Ni, Cu, An and Pb were in 0.1 to 1.11 ppb levels. The spike recoveries of the metallic impurities were in the range 86- 102% for the BARC materials. The analytical results of the BARC samples were found to be in reasonably good agreement with our previous method, and the analytical throughput can achieve up to 20 samples per hour for the analysis of 5 elements.

  19. Antireflective Coatings using Layer-by-Layer Self Assembly of Silica and Titania Nanoparticles

    NASA Astrophysics Data System (ADS)

    Velasco Castedo, Raisa; Lal, Anitesh Anand; Mazilu, Dan

    2011-03-01

    It is known that glass substrates (borosilicate glass) reflect about 4% of light at each air/glass interface and thus, they transmit only 92% of light. For some devices like camera lenses, it is important to maximize the amount of transmitted light. Previous research has demonstrated that it is possible to do so by adding antireflective coatings to the substrates. Our research aimed to deposit thin films on glass substrates that would minimize the reflectance of light and thus, maximize its transmittance. The thin films consisted of multiple alternating layers of silica and titania nanoparticles following the theory behind double-quarter periodic systems and were deposited on the substrates via the ISAM (ionically self-assembled monolayers) technique. Several experiments were conducted in order to investigate the factors that affected the quality of the coatings and some of the significant factors observed were the pH and the molarity of the silica, titania and PDDA solutions. A number of factor-level combinations yielded transmittances in excess of 96%, well above the value for uncoated substrates. R.E.Lee Summer Research Program at Washington and Lee University.

  20. Broadband terahertz absorption enabled by coating an ultrathin antireflection film on doped semiconductor.

    PubMed

    Wu, Hongxing; Shi, Fenghua; Chen, Yihang

    2016-09-01

    We show that perfect absorption of terahertz wave can be achieved in a compact system where an ultrathin film of lossless dielectric is coated on a doped semiconductor substrate. Due to the nontrivial reflection phase shift at the interface between the two media, strong resonant behavior and the concomitant antireflection occur at wavelengths that are much larger than the thickness of the dielectric film, resulting in strong absorption of the incident wave in a wide frequency range. Using this mechanism, we design a broadband terahertz absorber by coating a Ge film on a highly doped GaAs substrate. We show that such a system not only has a perfect absorption peak, but also exhibits high absorptance (over 0.9) within a fractional bandwidth of over 20%. By varying the free carrier density in the GaAs substrate, the central frequency of the absorption band can be tuned from 1.79 to 2.69 THz. In addition, the absorption performance of the proposed system is shown to be insensitive to both incident angle and polarization. Our results offer a low-cost way for the design of absorption-based THz devices. PMID:27607670

  1. The POLARBEAR Cosmic Microwave Background Polarization Experiment and Anti-Reflection Coatings for Millimeter Wave Observations

    NASA Astrophysics Data System (ADS)

    Quealy, Erin Elizabeth

    polarized reflections off of the refractive optics inside the receiver. Specifically, the antenna-coupled detector scheme relies on a high dielectric lenslet for each pixel on the focal plane. A large portion of this thesis discusses development of anti-reflection (AR) coatings for the high curvature lenslet surface. The AR coating technologies discussed are also applicable to other optical elements, such as reimaging lenses and half-wave plates. A single layer coating is used on the pbone lenslet array, and a two layer coating is presented for use in pbtwo. The two layer coating method can be extended to wider bandwidth AR coatings.

  2. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    SciTech Connect

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defect density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.

  3. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    DOE PAGESBeta

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defectmore » density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.« less

  4. Highly transparent triboelectric nanogenerator for harvesting water-related energy reinforced by antireflection coating.

    PubMed

    Liang, Qijie; Yan, Xiaoqin; Gu, Yousong; Zhang, Kui; Liang, Mengyuan; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-01-01

    Water-related energy is an inexhaustible and renewable energy resource in our environment, which has huge amount of energy and is not largely dictated by daytime and sunlight. The transparent characteristic plays a key role in practical applications for some devices designed for harvesting water-related energy. In this paper, a highly transparent triboelectric nanogenerator (T-TENG) was designed to harvest the electrostatic energy from flowing water. The instantaneous output power density of the T-TENG is 11.56 mW/m(2). Moreover, with the PTFE film acting as an antireflection coating, the maximum transmittance of the fabricated T-TENG is 87.4%, which is larger than that of individual glass substrate. The T-TENG can be integrated with silicon-based solar cell, building glass and car glass, which demonstrates its potential applications for harvesting waste water energy in our living environment and on smart home system and smart car system. PMID:25765205

  5. Robust antireflection coatings By UV cross-linking of silica nanoparticles and diazo-resin polycation

    NASA Astrophysics Data System (ADS)

    Ridley, Jason I.; Heflin, James R.; Ritter, Alfred L.

    2007-09-01

    Antireflection coatings have been fabricated by self-assembly using silica nanoparticles. The ionic self-assembled multilayer (ISAM) films are tightly packed and homogeneous. While the geometric properties of a matrix of spherical particles with corresponding void interstices are highly suitable to meet the conditions for minimal reflectivity, it is also a cause for the lack of cohesion within the constituent body, as well as to the substrate surface. This study investigates methods for improving the interconnectivity of the nanoparticle structure. One such method involves UV curing of diazo-resin (DAR)/silica nanoparticle films, thereby converting the ionic interaction into a stronger covalent bond. Factorial analysis and response surface methods are incorporated to determine factors that affect film properties, and to optimize their optical and adhesive capabilities. The second study looks at the adhesive strength of composite multilayer films. Films are fabricated with silica nanoparticles and poly(allylamine hydrochloride) (PAH), and dipped into aqueous solutions of PAH and poly(methacrylic acid, sodium salt) (PMA) to improve cohesion of silica nanoparticles in the matrix, as well as binding strength to the substrate surface. The results of the two studies are discussed.

  6. Highly transparent triboelectric nanogenerator for harvesting water-related energy reinforced by antireflection coating

    PubMed Central

    Liang, Qijie; Yan, Xiaoqin; Gu, Yousong; Zhang, Kui; Liang, Mengyuan; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-01-01

    Water-related energy is an inexhaustible and renewable energy resource in our environment, which has huge amount of energy and is not largely dictated by daytime and sunlight. The transparent characteristic plays a key role in practical applications for some devices designed for harvesting water-related energy. In this paper, a highly transparent triboelectric nanogenerator (T-TENG) was designed to harvest the electrostatic energy from flowing water. The instantaneous output power density of the T-TENG is 11.56 mW/m2. Moreover, with the PTFE film acting as an antireflection coating, the maximum transmittance of the fabricated T-TENG is 87.4%, which is larger than that of individual glass substrate. The T-TENG can be integrated with silicon-based solar cell, building glass and car glass, which demonstrates its potential applications for harvesting waste water energy in our living environment and on smart home system and smart car system. PMID:25765205

  7. Ga-doped ZnO conducting antireflection coatings for crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Estrich, N. A.; Hook, D. H.; Smith, A. N.; Leonard, J. T.; Laughlin, B.; Maria, J.-P.

    2013-06-01

    Transparent, conductive gallium-doped ZnO thin films are evaluated for application as conducting antireflection coatings (ARC) for crystalline silicon solar cells as a means to enhance efficiency by reducing the overall resistivity of the photovoltaic circuit. All Ga-doped ZnO thin films in this study were deposited using pulsed laser deposition. Synthesis conditions were first optimized for maximum electrical resistivity and minimal visible light absorption. The ideal combination contained 1 mol. % Ga doping and exhibited ˜90% transmission, with resistivity in the 1 × 10-3 ohm-cm range. Optimized films were prepared on reference flat silicon wafers with known dopant densities and on commercially obtained solar cell emitters without ARCs. Circular transmission line method measurements were used to measure specific contact resistivity (ρc). For n-type doped solar cell emitters, contact resistivity values of 0.1 mΩ cm2 were observed repeatedly. These values are consistent with, or lower than, contact resistivities associated with conventional silver paste metallization.

  8. Anti-reflection coatings for silicon solar cells from hydrogenated diamond like carbon

    NASA Astrophysics Data System (ADS)

    Das, Debajyoti; Banerjee, Amit

    2015-08-01

    Aiming towards a specific application as antireflection coatings (ARC) in Si solar cells, the growth of hydrogenated diamond like carbon (HDLC) films, by RF magnetron sputtering, has been optimized through comprehensive optical and structural studies. Various physical properties of the films e.g., (ID/IG) ratio in the Raman spectra, percentage of sp3 hybridization in XPS spectra, H-content in the network, etc., have been correlated with different ARC application properties e.g., transmittance, reflectance, optical band gap, refractive index, surface roughness, etc. The ARC properties have been optimized on unheated substrates, through systematic variations of RF power, gas flow rate, gas pressure and finally controlled introduction of hydrogen to the DLC network at its most favorable plasma parameters. The optimum HDLC films possess (T700)max ∼ 95.8%, (R700)min ∼ 3.87%, (n700)min ∼ 1.62 along with simultaneous (Eg)max ∼ 2.53 eV and ∼75.6% of sp3 hybridization in the C-network, corresponding to a bonded H-content of ∼23 at.%. Encouraging improvements in the ARC properties over the optimized DLC film were obtained with the controlled addition of hydrogen, and the optimum HDLC films appear quite promising for applications in Si solar cells. Systematic materials development has been performed through comprehensive understanding of the parameter space and its optimization, as elaborately discussed.

  9. Optimization of the antireflection coating of thin epitaxial crystalline silicon solar cells

    DOE PAGESBeta

    Selj, Josefine K.; Young, David; Grover, Sachit

    2015-08-28

    In this study we use an effective weighting function to include the internal quantum efficiency (IQE) and the effective thickness, Te, of the active cell layer in the optical modeling of the antireflection coating (ARC) of very thin crystalline silicon solar cells. The spectrum transmitted through the ARC is hence optimized for efficient use in the given cell structure and the solar cell performance can be improved. For a 2-μm thick crystalline silicon heterojunction solar cell the optimal thickness of the Indium Tin Oxide (ITO) ARC is reduced by ~8 nm when IQE data and effective thickness are taken intomore » account compared to the standard ARC optimization, using the AM1.5 spectrum only. The reduced ARC thickness will shift the reflectance minima towards shorter wavelengths and hence better match the absorption of very thin cells, where the short wavelength range of the spectrum is relatively more important than the long, weakly absorbed wavelengths. For this cell, we find that the optimal thickness of the ITO starts at 63 nm for very thin (1 μm) active Si layer and then increase with increasing Te until it saturates at 71 nm for Te > 30 μm.« less

  10. Modification Pathways for Copoly(2-oxazoline)s Enabling Their Application as Antireflective Coatings in Photolithography.

    PubMed

    Fimberger, Martin; Behrendt, Andreas; Jakopic, Georg; Stelzer, Franz; Kumbaraci, Volkan; Wiesbrock, Frank

    2016-02-01

    Chromophore-functionalized copoly(2-oxazoline)s are successfully evaluated as bottom antireflective coatings (BARCs) in high-resolution photolithography. With respect to UV light sources used in photolithographic production routines, anthracene is chosen as a chromophore. For application as polymer in BARCs, the copolymer poly(2-ethyl-2-oxazolin)45 -stat-poly(2-dec-9'-enyl-2-oxazolin)20 -stat-poly(2-(3'-(1"-(anthracen-9-ylmethyl)-1",2",3"-triazol-4-yl)propyl)-2-oxazolin)35 can be synthesized by the Huisgen cycloaddition click reaction of the copolymer poly(2-ethyl-2-oxazolin)45 -stat-poly(2-dec-9'-enyl-2-oxazolin)20 -stat-poly(2-pent-4'-inyl-2-oxazolin)35 and the corresponding azide-functionalized anthracenes. These copolymers can be crosslinked by the thermally induced thiol-ene reaction involving the unsaturated C=C bonds of the poly(2-dec-9'-enyl-2-oxazoline) repetition units and a multifunctional thiol as crosslinker. Tests of this BARC in a clean room under production conditions reveal a significant decrease of the swing-curve of a chemically amplified positive photoresist by more than 50%, hence significantly increasing the resolution of the photoresist. PMID:26619063

  11. Optimization of the antireflection coating of thin epitaxial crystalline silicon solar cells

    SciTech Connect

    Selj, Josefine K.; Young, David; Grover, Sachit

    2015-08-28

    In this study we use an effective weighting function to include the internal quantum efficiency (IQE) and the effective thickness, Te, of the active cell layer in the optical modeling of the antireflection coating (ARC) of very thin crystalline silicon solar cells. The spectrum transmitted through the ARC is hence optimized for efficient use in the given cell structure and the solar cell performance can be improved. For a 2-μm thick crystalline silicon heterojunction solar cell the optimal thickness of the Indium Tin Oxide (ITO) ARC is reduced by ~8 nm when IQE data and effective thickness are taken into account compared to the standard ARC optimization, using the AM1.5 spectrum only. The reduced ARC thickness will shift the reflectance minima towards shorter wavelengths and hence better match the absorption of very thin cells, where the short wavelength range of the spectrum is relatively more important than the long, weakly absorbed wavelengths. For this cell, we find that the optimal thickness of the ITO starts at 63 nm for very thin (1 μm) active Si layer and then increase with increasing Te until it saturates at 71 nm for Te > 30 μm.

  12. Study of major factors to affect photoresist profile on developable bottom anti-reflective coating process

    NASA Astrophysics Data System (ADS)

    Roh, Hyo Jung; Ju, Dong Kyu; Kim, Hyun Jin; Kim, Jaehyun

    2011-04-01

    As critical dimensions continue to shrink in lithography, new materials will be needed to meet the new demands imposed by this shrinkage. Recently, there are needs for novel materials with various substrates and immersing process, including double patterning process, a high resolution implant process, and so on. Among such materials, Developable Bottom Anti-reflective Coating material (DBARC) is a good candidate for high resolution implant application as well as double patterning. DBARC should have reflectivity control function as an ordinary BARC, as well as an appropriate solubility in TMAH-based conventional developer after exposure and bake process. The most distinguished advantage of DBARC is to skip BARC etch process that is required in normal BARC process. In spite of this advantage, the photoresist profile on DBARC could be influenced by components and process conditions of DBARC. Several groups have tried to solve this issue to implement DBARC to new process. We have studied material-related factors affecting photoresist profiles, such as a polymer, photo-acid generators (PAGs), and additives. And we explored the effect of process condition for photoresist and DBARC. In case of polymer, we studied the effect of dissolution rate in developer and crosslinking functionality. For PAGs and additives, the effect of acid diffusivity and cross-linking degree according to their bulkiness were examined. We also evaluated coated film stability in a photoresist solvent after BARC bake process and compared lithographic performance of various DBARC formulations. In addition, the effect of photoresist profile with bake condition of photoresist and DBARC were investigated. In this paper, we will demonstrate the most influential factors of DBARC to photoresist profile and suggest the optimum formulation and process condition for DBARC application.

  13. Studies and testing of antireflective (AR) coatings for soda-lime glass

    NASA Technical Reports Server (NTRS)

    Pastirik, E. M.; Sparks, T. G.; Coleman, M. G.

    1978-01-01

    Processes for producing antireflection films on glass are concentrated in three areas: acid etching of glass, plasma etching of glass, and acid development of sodium silicate films on glass. The best transmission was achieved through the acid etching technique, while the most durable films were produced from development of sodium silicate films. Control of the acid etching technique is presently inadequate for production implementation. While films having excellent antireflective properties were fabricated by plasma etching techniques, all were water soluble.

  14. Reflective and antireflective coatings for the optical chain of the ASTRI SST-2M prototype

    NASA Astrophysics Data System (ADS)

    Bonnoli, Giacomo; Canestrari, Rodolfo; Catalano, Osvaldo; Pareschi, Giovanni; Perri, Luca; Stringhetti, Luca

    2013-09-01

    ASTRI is a Flagship Project of the Italian Ministry of Education, University and Research, led by the Italian National Institute of Astrophysics, INAF. One of the main aims of the ASTRI Project is the design, construction and on-field verification of a dual mirror (2M) end-to-end prototype for the Small Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array. The ASTRI SST-2M prototype is designed according to the Schwarzschild-Couder optical scheme, and adopts a camera based on Silicon Photo Multipliers (SiPM); it will be assembled at the INAF astronomical site of Serra La Nave on mount Etna (Catania, Italy) in the second half of 2014, and will start scientific validation phase soon after. With its 4m wide primary dish, the telescope will be sensitive to multi-TeV Very High Energy (VHE) gamma rays up to 100 TeV and above, with a point spread function of ~2 arcminutes and a wide (semiaperture 4.8°) corrected field of view. The peculiarities of the optical design and of the SiPM bandpass pushed towards specifically optimized choices in terms of reflective coatings for both the primary and the secondary mirror. Fully dielectric multi-layer coatings have been developed and tested as an option for the primary mirror, aiming to filter out the large Night Sky Background contamination at wavelengths λ>~700 nm. On the other hand, for the large monolithic secondary mirror a simpler design with quartz-overcoated aluminium has been optimized for incidences far from normality. The conformation of the ASTRI camera in turn pushed towards the design of a reimaging system based on thin pyramidal light guides, that could be optionally integrated in the focal surface, aiming to increase the fill factor. An anti-reflective coating optimized for a wide range of incident angles faraway from normality was specifically developed to enhance the UV-optical transparency of these elements. The issues, strategy, simulations and experimental results are thoroughly

  15. The effects of the bottom anti-reflective coating with different baked temperatures and thicknesses on nanoscale patterns

    NASA Astrophysics Data System (ADS)

    Zheng, Jie; Li, Ling; Chen, Weidong

    2015-12-01

    The bottom anti-reflective coating (BARC) material can enhance the resolution of the nanopatterns structures in laser interference lithography process. In this study, WIDE-B ARC material was investigated to confirm the reduction of the vertical standing wave which leads to defect of nanopatterns. And the critical dimension (CD) of 100 nm L/S patterns with and without the application of BARC material was fabricated by laser interference lithography technology. The compared results showed that BARC can effectively reduce CD swing and obtain more uniform nanopatterns. Meanwhile, we also verified the influence of cured temperature and film thickness of BARC on the uniformity of nanopatterns.

  16. Evaluation of self-focusing influence on laser-induced damage threshold of anti-reflective coated windows

    NASA Astrophysics Data System (ADS)

    Rakickas, T.; Kudriašov, V.; Sirutkaitis, V.; Grigonis, R.; Gaižauskas, E.

    2005-12-01

    For high intensity lasers it is very important to choose appropriate optical elements. Since invention of high power lasers laser-induced damage of optical coatings was subject of extensive investigations. At high laser intensities the self-focusing in optical elements appears and intensity at rear optics surface can be much higher than at the front surface. Due to this damage of rear-surface can be reached much faster than damage of the front surface. We investigated the influence of self-focusing on damage threshold in fused-silica windows with anti-reflective coatings on both sides. In our experiments we used titanium-sapphire chirped pulse amplification system (130 fs, 2 mJ, 1 kHz repetition rate pulses at 800 nm). We have tested 1 mm, 3 mm and 6 mm thickness fused-silica windows with identical anti-reflective coatings. The front surface of the samples was placed in the waist of focused beam. The experiments were performed for effective spot diameters on the front 145 μm, 95 μm and 43 μm respectively. The experiments showed the self-focusing of beam inside the fused silica window and self-focusing dependence on initial beam diameter. The damage behavior was dependent on irradiation history. Also we found quite strong nonlinear absorption in fused silica.

  17. Wide band antireflective coatings Al2O3 / HfO2 / MgF2 for UV region

    NASA Astrophysics Data System (ADS)

    Winkowski, P.; Marszałek, Konstanty W.

    2013-07-01

    Deposition technology of the three layers antireflective coatings consists of hafnium compound are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5x10-5 mbar in presence of oxygen and fluoride films by thermal evaporation. Substrate temperature was 250°C. Coatings were deposited onto optical lenses made from quartz glass (Corning HPFS). Thickness and deposition rate were controlled by thickness measuring system Inficon XTC/2. Simulations leading to optimization of thickness and experimental results of optical measurements carried during and after deposition process were presented. Physical thickness measurements were made during deposition process and were equal to 43 nm/74 nm/51 nm for Al2O3 / HfO2 / MgF2 respectively. Optimization was carried out for ultraviolet region from 230nm to the beginning of visible region 400 nm. In this region the average reflectance of the antireflective coating was less than 0.5% in the whole range of application.

  18. A simplified method for generating periodic nanostructures by interference lithography without the use of an anti-reflection coating

    NASA Astrophysics Data System (ADS)

    Kapon, Omree; Muallem, Merav; Palatnik, Alex; Aviv, Hagit; Tischler, Yaakov. R.

    2015-11-01

    Interference lithography has proven to be a useful technique for generating periodic sub-diffraction limited nanostructures. Interference lithography can be implemented by exposing a photoresist polymer to laser light using a two-beam arrangement or more simply a one beam configuration based on a Lloyd's Mirror Interferometer. For typical photoresist layers, an anti-reflection coating must be deposited on the substrate to prevent adverse reflections from cancelling the holographic pattern of the interfering beams. For silicon substrates, such coatings are typically multilayered and complex in composition. By thinning the photoresist layer to a thickness well below the quarter wavelength of the exposing beam, we demonstrate that interference gratings can be generated without an anti-reflection coating on the substrate. We used ammonium dichromate doped polyvinyl alcohol as the positive photoresist because it provides excellent pinhole free layers down to thicknesses of 40 nm, and can be cross-linked by a low-cost single mode 457 nm laser, and can be etched in water. Gratings with a period of 320 nm and depth of 4 nm were realized, as well as a variety of morphologies depending on the photoresist thickness. This simplified interference lithography technique promises to be useful for generating periodic nanostructures with high fidelity and minimal substrate treatments.

  19. A simplified method for generating periodic nanostructures by interference lithography without the use of an anti-reflection coating

    SciTech Connect

    Kapon, Omree; Muallem, Merav; Palatnik, Alex; Aviv, Hagit; Tischler, Yaakov R.

    2015-11-16

    Interference lithography has proven to be a useful technique for generating periodic sub-diffraction limited nanostructures. Interference lithography can be implemented by exposing a photoresist polymer to laser light using a two-beam arrangement or more simply a one beam configuration based on a Lloyd's Mirror Interferometer. For typical photoresist layers, an anti-reflection coating must be deposited on the substrate to prevent adverse reflections from cancelling the holographic pattern of the interfering beams. For silicon substrates, such coatings are typically multilayered and complex in composition. By thinning the photoresist layer to a thickness well below the quarter wavelength of the exposing beam, we demonstrate that interference gratings can be generated without an anti-reflection coating on the substrate. We used ammonium dichromate doped polyvinyl alcohol as the positive photoresist because it provides excellent pinhole free layers down to thicknesses of 40 nm, and can be cross-linked by a low-cost single mode 457 nm laser, and can be etched in water. Gratings with a period of 320 nm and depth of 4 nm were realized, as well as a variety of morphologies depending on the photoresist thickness. This simplified interference lithography technique promises to be useful for generating periodic nanostructures with high fidelity and minimal substrate treatments.

  20. Novel low-reflective index fluoropolymers-based top anti-reflective coatings (TARC) for 193-nm lithography

    NASA Astrophysics Data System (ADS)

    Yamashita, Tsuneo; Hayami, Takashi; Ishikawa, Takuji; Kanemura, Takashi; Aoyama, Hirokazu

    2007-03-01

    Implant lithography, which has up to now utilized 365-nm (i-line) and 248-nm (KrF) light sources, must now turn to 193-nm (ArF) sources. In implant lithography, an anti-reflective material is often used to coat the resist-film. The top anti-reflective coating (abbreviated to TARC) is most often used to reduce CD swing. TARC materials must have low refractive index and water solubility. The TARC materials for used 193-nm use must have very low reflective index and alternatives to perfluorooctylsulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) must be found. We synthesized some novel fluorinated amorphous polymers as 193-nm TARC candidates. Their fundamental properties were characterized, such as transparency and reflective index at 193-nm (wavelength) along with their solubility in water and a standard alkaline developer. High transparency, i.e., k value less than 0.01, and very low reflective index, i.e., lower than n=1.4 at 193-nm wavelength are confirmed. Their dissolution behaviors are studied using the Quartz Crystal Microbalance (QCM) method. In surprise finding, we find that several of the polymers examined, those that have high fluorine content, dissolved in water. Test results show that the proposed polymers can be applied as top anti reflective coatings .

  1. The Angular Performance Behavior Of Triple Junction Solar Cells With Different Antireflection Coatings For High Temperature Space Missions

    NASA Astrophysics Data System (ADS)

    Hulsheger, Tim; Brandt, Christian; Caon, Antonio; Fiebrich, Horst K.; Andreev, Thomas

    2011-10-01

    The angular behavior of GaInP2/GaAs/Ge triple junction solar cells is studied from 0° up to 86°. Angle dependent short circuit currents of cells with antireflection coatings such as TiO2/Al2O3 and Al2O3 are compared to results of uncoated cells. Performance benefits from each coating are measured before and after cover glass coverage. Related temperature effects are predicted taking into account measured absorption coefficients in order to address on the coating of choice for high temperature solar generators. The influence of the sun light intensities from 1 AM0 to 8 AM0 is put in relation with basic semiconductor properties.

  2. Antireflecting and polarizing dielectric single-layer coating at oblique incidence on absorbing substrates at λ = 10.6 μm.

    NASA Astrophysics Data System (ADS)

    Cojocaru, E.; Julea, T.

    Transparent single-layer antireflection coating on an absorbing substrate for p and s polarizations of the infrared light at λ = 10.6 μm as a function of the angle of incidence is studied in this paper. Two cases of low absorbing Ge, GaAs, ZnSe substrates and high absorbing Cu substrate are considered. It is found that the Cu substrate coated by an adequate antireflecting single-layer film functions as an excellent Rs = 0 reflection polarizer.

  3. Graphene oxide as a p-dopant and an anti-reflection coating layer, in graphene/silicon solar cells

    NASA Astrophysics Data System (ADS)

    Yavuz, S.; Kuru, C.; Choi, D.; Kargar, A.; Jin, S.; Bandaru, P. R.

    2016-03-01

    It is shown that coating graphene-silicon (Gr/Si) Schottky junction based solar cells with graphene oxide (GO) improves the power conversion efficiency (PCE) of the cells, while demonstrating unprecedented device stability. The PCE has been shown to be increased to 10.6% (at incident radiation of 100 mW cm-2) for the Gr/Si solar cell with an optimal GO coating thickness compared to 3.6% for a bare/uncoated Gr/Si solar cell. The p-doping of graphene by the GO, which also serves as an antireflection coating (ARC) has been shown to be a main contributing factor to the enhanced PCE. A simple spin coating process has been used to apply GO with thickness commensurate with an anti-refection coating (ARC) and indicates the suitability of the developed methodology for large-scale solar cell assembly.It is shown that coating graphene-silicon (Gr/Si) Schottky junction based solar cells with graphene oxide (GO) improves the power conversion efficiency (PCE) of the cells, while demonstrating unprecedented device stability. The PCE has been shown to be increased to 10.6% (at incident radiation of 100 mW cm-2) for the Gr/Si solar cell with an optimal GO coating thickness compared to 3.6% for a bare/uncoated Gr/Si solar cell. The p-doping of graphene by the GO, which also serves as an antireflection coating (ARC) has been shown to be a main contributing factor to the enhanced PCE. A simple spin coating process has been used to apply GO with thickness commensurate with an anti-refection coating (ARC) and indicates the suitability of the developed methodology for large-scale solar cell assembly. Electronic supplementary information (ESI) available: (i) Experimental methods, (ii) optical images of devices with and without graphene oxide (GO), (iii) comparison of the power conversion efficiency (PCE) due to the GO coating and nitric acid doping, (iv) specular and diffuse reflectance measurements, (v) stability data of pristine graphene/silicon (Gr/Si) solar cells. See DOI: 10.1039/c5

  4. Optimal design of antireflection coating and experimental verification by plasma enhanced chemical vapor deposition in small displays

    SciTech Connect

    Yang, S. M.; Hsieh, Y. C.; Jeng, C. A.

    2009-03-15

    Conventional antireflection coating by thin films of quarter-wavelength thickness is limited by material selections and these films' refractive indices. The optimal design by non-quarter-wavelength thickness is presented in this study. A multilayer thin-film model is developed by the admittance loci to show that the two-layer thin film of SiN{sub x}/SiO{sub y} at 124/87 nm and three layer of SiN{sub x}/SiN{sub y}/SiO{sub z} at 58/84/83 nm can achieve average transmittances of 94.4% and 94.9%, respectively, on polymer, glass, and silicon substrates. The optimal design is validated by plasma enhanced chemical vapor deposition of N{sub 2}O/SiH{sub 4} and NH{sub 3}/SiH{sub 4} to achieve the desired optical constants. Application of the antireflection coating to a 4 in. liquid crystal display demonstrates that the transmittance is over 94%, the mean luminance can be increased by 25%, and the total reflection angle increased from 41 deg. to 58 deg.

  5. Synthesis of antireflective silica coatings through the synergy of polypeptide layer-by-layer assemblies and biomineralization

    NASA Astrophysics Data System (ADS)

    Lee, Yung-Lun; Lin, Ting-Xuan; Hsu, Feng-Ming; Jan, Jeng-Shiung

    2016-01-01

    We report a versatile approach to synthesize silica coatings with antireflective (AR) characteristics through the combination of a layer-by-layer (LbL) assembly technique and biomineralization. LbL assembled decanoyl-modified poly(l-lysine)/poly(l-glutamic acid) (PLL-g-Dec/PLGA) multilayer films were used as templates for silica mineralization, followed by calcination. The specific deposition of silica onto the LbL polypeptide assemblies through amine-catalyzed polycondensation resulted in silica coatings that exhibited the transcription of the nano-/microstructured polypeptide films and their film thickness and porosity can be tuned by varying the number of bilayers, degree of substitution, and PLL molecular weight. AR silica coatings exhibiting more than 6% increase in transmittance in the near UV/visible spectral range can be obtained at an optimized refractive index, thickness, and surface roughness. The abrasion test showed that the silica coatings exhibited sufficient structural durability due to continuous silica nanostructures and low surface roughness. This study demonstrated that nanostructured thin films can be synthesized for AR coatings using the synergy between the LbL assembly technique and biomineralization.We report a versatile approach to synthesize silica coatings with antireflective (AR) characteristics through the combination of a layer-by-layer (LbL) assembly technique and biomineralization. LbL assembled decanoyl-modified poly(l-lysine)/poly(l-glutamic acid) (PLL-g-Dec/PLGA) multilayer films were used as templates for silica mineralization, followed by calcination. The specific deposition of silica onto the LbL polypeptide assemblies through amine-catalyzed polycondensation resulted in silica coatings that exhibited the transcription of the nano-/microstructured polypeptide films and their film thickness and porosity can be tuned by varying the number of bilayers, degree of substitution, and PLL molecular weight. AR silica coatings exhibiting

  6. Progress in the Growth of Yb:S-FAP Laser Crystals

    SciTech Connect

    Schaffers, K I; Tassano, J B; Waide, P A; Payne, S A; Morris, R C

    2000-07-01

    The crystal growth of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] is being studied for 1.047-{micro}m laser operation. These crystals are not yet routinely available and the growth of high optical quality, low loss crystals poses a challenge due to a number of crystal growth issues, including, cloudiness, bubble core defects, anomalous absorption, low-angle grain boundaries, and cracking. At this time, a growth process has been formulated to simultaneously eliminate or greatly diminish each of the defects yielding high quality material. Laser slabs of dimension 4.0 x 6.0 x 0.75 cm are being fabricated from sub-scale pieces using the diffusion bonding technique.

  7. How reduced vacuum pumping capability in a coating chamber affects the laser damage resistance of HfO2/SiO2 antireflection and high reflection coatings.

    DOE PAGESBeta

    Field, Ella Suzanne; Bellum, John Curtis; Kletecka, Damon E.

    2016-06-01

    Optical coatings with the highest laser damage thresholds rely on clean conditions in the vacuum chamber during the coating deposition process. A low base pressure in the coating chamber, as well as the ability of the vacuum system to maintain the required pressure during deposition, are important aspects of limiting the amount of defects in an optical coating that could induce laser damage. Our large optics coating chamber at Sandia National Laboratories normally relies on three cryo pumps to maintain low pressures for e-beam coating processes. However, on occasion, one or more of the cryo pumps have been out ofmore » commission. In light of this circumstance, we explored how deposition under compromised vacuum conditions resulting from the use of only one or two cryo pumps affects the laser-induced damage thresholds of optical coatings. Finally, the coatings of this study consist of HfO2 and SiO2 layer materials and include antireflection coatings for 527 nm at normal incidence, and high reflection coatings for 527 nm, 45⁰ angle of incidence (AOI), in P-polarization (P-pol).« less

  8. Characterization of 1064nm nanosecond laser-induced damage on antireflection coatings grown by atomic layer deposition.

    PubMed

    Liu, Zhichao; Chen, Songlin; Ma, Ping; Wei, Yaowei; Zheng, Yi; Pan, Feng; Liu, Hao; Tang, Gengyu

    2012-01-16

    Damage tests are carried out at 1064nm to measure the laser resistance of TiO(2)/Al(2)O(3) and HfO(2)/Al(2)O(3) antireflection coatings grown by atomic layer deposition (ALD). The damage results are determined by S-on-1 and R-on-1 tests. Interestingly, the damage performance of ALD coatings is similar to those grown by conventional e-beam evaporation process. A decline law of damage resistance under multiple irradiations is revealed. The influence of growth temperature on damage performance has been investigated. Result shows that the crystallization of TiO(2) layer at higher temperature could lead to numerous absorption defects that reduce the laser-induced damage threshold (LIDT). In addition, it has been found that using inorganic compound instead of organic compound as precursors for ALD process maybe effectively prevent carbon impurities in films and will increase the LIDT obviously. PMID:22274431

  9. Deep-ultraviolet tailored- and low-refractive index antireflection coatings for light-extraction enhancement of light emitting diodes

    NASA Astrophysics Data System (ADS)

    Yan, Xing; Shatalov, Max; Saxena, Tanuj; Shur, Michael S.

    2013-04-01

    An omnidirectional antireflection (AR) coating for a deep-ultraviolet (UV) AR band is designed and fabricated on the sapphire substrate of a deep-UV flip-chip light-emitting diode (LED) device. The two-layer AR coating uses the tailored- and low-refractive index nanoporous alumina fabricated by glancing-angle deposition methodology. The AR coating effectively matches the refractive indices between the air and sapphire substrate. At close-to-normal angles of incidence, this AR coating almost completely eliminates the Fresnel reflection at the sapphire/air interface of the deep-UV LED device. The resulting improvement of the light-extraction efficiency by 8% is in good agreement with the simulation results. For a total thickness of 172 nm for the two-layer AR coating, extinction was negligible (<2%). The results show that nanoporous alumina thin films are excellent tailored- and low-refractive index thin film materials for high-performance deep-UV AR coating applications.

  10. Functional photocatalytically active and scratch resistant antireflective coating based on TiO2 and SiO2

    NASA Astrophysics Data System (ADS)

    Mazur, M.; Wojcieszak, D.; Kaczmarek, D.; Domaradzki, J.; Song, S.; Gibson, D.; Placido, F.; Mazur, P.; Kalisz, M.; Poniedzialek, A.

    2016-09-01

    Antireflection (AR) multilayer coating, based on combination of five TiO2 and SiO2 thin films, was deposited by microwave assisted reactive magnetron sputtering process on microscope glass substrates. In this work X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy and wettability measurements were used to characterize the structural and surface properties of the deposited coating. These studies revealed that prepared coating was amorphous with low surface roughness. Photocatalytic properties were determined based on phenol decomposition reaction. Measurements of optical properties showed that transmittance in the visible wavelength range was increased after the deposition of AR coating as-compared to bare glass substrate. The mechanical properties were determined on the basis of nano-indentation and scratch resistance tests. Performed research has shown that deposition of an additional thin 10 nm thick TiO2 thin film top layer, the prepared AR coating was photocatalytically active, hydrophobic, scratch resistant and had increased hardness as-compared to bare glass substrate. These results indicate that prepared AR multilayer could be used also as a self-cleaning and protective coating.

  11. Antireflection coating formed by plasma-enhanced chemical-vapor deposition for terahertz-frequency germanium optics

    NASA Astrophysics Data System (ADS)

    Hosako, Iwao

    2003-07-01

    A method of manufacturing optical coatings for germanium optics used at terahertz frequencies has been developed. The various optical coatings used at terahertz frequencies are difficult to manufacture conventionally because these coatings must be as thick as several tens of micrometers, which is far thicker than those used in the optical region. One way to overcome this problem is to form a silicon oxide layer through plasma-enhanced chemical-vapor deposition, with silane (SiH4) as a source gas. Using this method, I formed 21-μm-thick silicon oxide films as antireflection (AR) layers for germanium optics and obtained low reflection at 1.7 THz (wavelength, λ = 175 μm). This method is easily applied to large-aperture optics and micro-optics as well as to optics with a complex surface form. The AR coatings can also be formed for photoconductive detectors made from germanium doped with gallium at a low temperature (160 °C) this low temperature ensures that the doped impurities in the germanium do not diffuse. Fabrication of optical coatings upon substrates that have refractive indices of 3.84-11.7 may also be possible by control of the refractive indices of the deposited layers.

  12. Synthesis of antireflective silica coatings through the synergy of polypeptide layer-by-layer assemblies and biomineralization.

    PubMed

    Lee, Yung-Lun; Lin, Ting-Xuan; Hsu, Feng-Ming; Jan, Jeng-Shiung

    2016-01-28

    We report a versatile approach to synthesize silica coatings with antireflective (AR) characteristics through the combination of a layer-by-layer (LbL) assembly technique and biomineralization. LbL assembled decanoyl-modified poly(l-lysine)/poly(l-glutamic acid) (PLL-g-Dec/PLGA) multilayer films were used as templates for silica mineralization, followed by calcination. The specific deposition of silica onto the LbL polypeptide assemblies through amine-catalyzed polycondensation resulted in silica coatings that exhibited the transcription of the nano-/microstructured polypeptide films and their film thickness and porosity can be tuned by varying the number of bilayers, degree of substitution, and PLL molecular weight. AR silica coatings exhibiting more than 6% increase in transmittance in the near UV/visible spectral range can be obtained at an optimized refractive index, thickness, and surface roughness. The abrasion test showed that the silica coatings exhibited sufficient structural durability due to continuous silica nanostructures and low surface roughness. This study demonstrated that nanostructured thin films can be synthesized for AR coatings using the synergy between the LbL assembly technique and biomineralization. PMID:26752150

  13. Antireflection and self-cleaning properties of a moth-eye-like surface coated with TiO2 particles.

    PubMed

    Nakata, Kazuya; Sakai, Munetoshi; Ochiai, Tsuyoshi; Murakami, Taketoshi; Takagi, Katsuhiko; Fujishima, Akira

    2011-04-01

    Poly(ethylene terephthalate) (PET) films with a moth-eye-like surface are coated with TiO(2) particles to form self-cleaning antireflective films. The use of a TiO(2) suspension of high concentration to coat the PET surface produces a thicker TiO(2) layer with smaller pores, whereas a low concentration of a TiO(2) suspension gives a thinner layer of TiO(2) with larger pores. The PET films coated with TiO(2) particles exhibit a high transmittance of 76-95% and almost no absorption in the range of 400-800 nm. The PET films coated with a TiO(2) suspension with a concentration of ≥2 vol % exhibit superhydrophilicity after irradiation with UV light. After irradiation, the superhydrophilic nature is retained for at least 18 days. The TiO(2)-coated PET films showed the ability to decompose methylene blue under UV irradiation. PMID:21391643

  14. Thin film gallium arsenide solar cell research. Third quarterly project report, September 1, 1980-November 30, 1980. [Antireflection coating

    SciTech Connect

    Chu, S. S.

    1980-12-01

    The major objective of this contract is to produce gallium arsenide solar cells of 10% conversion efficiency in films of less than 10 micrometers thick which have been deposited by chemical vapor deposition on graphite or tungsten coated graphite substrates. Major efforts during this quarter were directed to: (1) the optimization of the deposition of gallium arsenide films of 10 ..mu..m thickness or less on tungsten/graphic substrates, (2) the investigation of the effectiveness of various grain boundary passivation techniques, (3) the deposition of tantalum pentoxide by ion beam sputtering as an antireflection coating, (4) the deposition of gallium aluminium arsenide by the organometallic process, and (5) the fabrication and characterization of large area Schottky barrier type solar cells from gallium arsenide films of about 10 ..mu..m thickness. Various grain boundary passivation techniques, such as the anodic oxidation, thermal oxidation, and ruthenium treatment, have been investigated. The combination of thermal oxidation and ruthenium treatment has been used to fabricate Schottky barrier type solar cells. Large area MOS solar cells of 9 cm/sup 2/ area with AMl efficiency of 8.5% have been fabricated from ruthenium treated gallium arsenide films of 10 ..mu..m thickness. The construction of the apparatus for the deposition of gallium aluminum arsenide by the organometallic process has been completed. The deposition of good quality tantalum pentoxide film as an antireflection coating has been carried out by the ion beam sputtering technique. The short-circuit current density and AMl efficiency of the solar cells are increased by approximately 60%, with a slight increase in the open-circuit voltage. Details are presented. (WHK)

  15. 17.1%-Efficient Multi-Scale-Textured Black Silicon Solar Cells without Dielectric Antireflection Coating: Preprint

    SciTech Connect

    Toor, F.; Page, M. R.; Branz, H. M.; Yuan, H. C.

    2011-07-01

    In this work we present 17.1%-efficient p-type single crystal Si solar cells with a multi-scale-textured surface and no dielectric antireflection coating. Multi-scale texturing is achieved by a gold-nanoparticle-assisted nanoporous etch after conventional micron scale KOH-based pyramid texturing (pyramid black etching). By incorporating geometric enhancement of antireflection, this multi-scale texturing reduces the nanoporosity depth required to make silicon 'black' compared to nanoporous planar surfaces. As a result, it improves short-wavelength spectral response (blue response), previously one of the major limiting factors in 'black-Si' solar cells. With multi-scale texturing, the spectrum-weighted average reflectance from 350- to 1000-nm wavelength is below 2% with a 100-nm deep nanoporous layer. In comparison, roughly 250-nm deep nanopores are needed to achieve similar reflectance on planar surface. Here, we characterize surface morphology, reflectivity and solar cell performance of the multi-scale textured solar cells.

  16. ZnSe hollow nanospheres in mechanically stable near-IR antireflection coatings for ZnSe substrates.

    PubMed

    Li, Chao; Luo, Rui-Chun; Mao, Yong-Qiang; Du, Xi-Wen; Yang, Jing

    2016-09-01

    Though possessing low absorption throughout a wide infrared (IR) spectral regime, owing to a high refractive index, zinc selenide substrates are generally covered by antireflection coatings (ARCs) for practical optical uses. However, achieving a high transmission of ZnSe substrates in the near-IR (NIR) region is still challenging. Herein, for the first time, colloidal ZnSe hollow nanospheres (HNSs) smaller than 100 nm were prepared and adopted to assemble ARCs for ZnSe substrates. The voiding kinetics of the HNSs was found to agree well with the nanoscale Kirkendall effect, and the self-diffusion of the Zn ion in the core was faster than its diffusion through the ZnSe shell. With single-index ARCs, the transmission of ZnSe substrates was remarkably enhanced in the NIR region, with up to an 18% increase at 840 nm. Besides, the ZnSe HNS-based ARCs showed superior mechanical stability even under violent ultrasonication in organic solutions. We expect that ZnSe HNSs will make it possible to construct graded-index ARCs to realize omnidirectional and broadband antireflection in IR, through further tuning of HNSs' void fraction. PMID:27482737

  17. ZnSe hollow nanospheres in mechanically stable near-IR antireflection coatings for ZnSe substrates

    NASA Astrophysics Data System (ADS)

    Li, Chao; Luo, Rui-Chun; Mao, Yong-Qiang; Du, Xi-Wen; Yang, Jing

    2016-09-01

    Though possessing low absorption throughout a wide infrared (IR) spectral regime, owing to a high refractive index, zinc selenide substrates are generally covered by antireflection coatings (ARCs) for practical optical uses. However, achieving a high transmission of ZnSe substrates in the near-IR (NIR) region is still challenging. Herein, for the first time, colloidal ZnSe hollow nanospheres (HNSs) smaller than 100 nm were prepared and adopted to assemble ARCs for ZnSe substrates. The voiding kinetics of the HNSs was found to agree well with the nanoscale Kirkendall effect, and the self-diffusion of the Zn ion in the core was faster than its diffusion through the ZnSe shell. With single-index ARCs, the transmission of ZnSe substrates was remarkably enhanced in the NIR region, with up to an 18% increase at 840 nm. Besides, the ZnSe HNS-based ARCs showed superior mechanical stability even under violent ultrasonication in organic solutions. We expect that ZnSe HNSs will make it possible to construct graded-index ARCs to realize omnidirectional and broadband antireflection in IR, through further tuning of HNSs’ void fraction.

  18. Broadband omnidirectional antireflection coatings for metal-backed solar cells optimized using simulated annealing algorithm incorporated with solar spectrum.

    PubMed

    Chang, Yin-Jung; Chen, Yu-Ting

    2011-07-01

    Broadband omnidirectional antireflection (AR) coatings for solar cells optimized using simulated annealing (SA) algorithm incorporated with the solar (irradiance) spectrum at Earth's surface (AM1.57 radiation) are described. Material dispersions and reflections from the planar backside metal are considered in the rigorous electromagnetic calculations. Optimized AR coatings for bulk crystalline Si and thin-film CuIn(1-x)GaxSe(2) (CIGS) solar cells as two representative cases are presented and the effect of solar spectrum in the AR coating designs is investigated. In general, the angle-averaged reflectance of a solar-spectrum-incorporated AR design is shown to be smaller and more uniform in the spectral range with relatively stronger solar irradiance. By incorporating the transparent conductive and buffer layers as part of the AR coating in CIGS solar cells (2μm-thick CIGS layer), a single MgF(2) layer could provide an average reflectance of 8.46% for wavelengths ranging from 350 nm to 1200 nm and incident angles from 0° to 80°. PMID:21747557

  19. Stability of anti-reflection coatings via the self-assembly encapsulation of silica nanoparticles by diazo-resins

    NASA Astrophysics Data System (ADS)

    Metzman, Jonathan S.; Ridley, Jason I.; Khalifa, Moataz B.; Heflin, James R.

    2015-12-01

    A modified silica nanoparticle (MSNP) solution was formed by the encapsulation of negatively charged silica nanoparticles by the UV-crosslinkable polycation oligomer diazo-resin (DAR). Appropriate DAR encapsulation concentrations were determined by use of zeta-potential and dynamic light scattering measurements. The MSNPs were used in conjunction with poly(styrene sulfonate) (PSS) to grow homogenous ionic self-assembled multilayer anti-reflection coatings. Stability was induced within the films by the exposure of UV-irradiation that allowed for crosslinking of the DAR and PSS. The films were characterized by UV/vis/IR spectroscopy and field emission scanning electron microscopy. The transmission and reflection levels were >98.5% and <0.05%, respectively. The refractive indices resided in the 1.25-1.26 range. The solvent stability was tested by sonication of the films in a ternary solvent (H2O/DMF/ZnCl2 3:5:2 w/w/w).

  20. Antireflection-coated blue GaN laser diodes in an external cavity and Doppler-free indium absorption spectroscopy.

    PubMed

    Hildebrandt, Lars; Knispel, Richard; Stry, Sandra; Sacher, Joachim R; Schael, Frank

    2003-04-20

    Commercially available GaN-based laser diodes were antireflection coated in our laboratory and operated in an external cavity in a Littrow configuration. A total tuning range of typically 4 nm and an optical output power of up to 30 mW were observed after optimization of the external cavity. The linewidth was measured with a beterodyne technique, and 0.8 MHz at a sweep time of 50 ms was obtained. The mode-hop-free tuning range was more than 50 GHz. We demonstrated the performance of the laser by detecting the saturated absorption spectrum of atomic indium at 410 nm, allowing observation of well-resolved Lamb dips. PMID:12716152

  1. Shallow-grating coupler with optimized anti-reflection coating for high-efficiency optical output into multimode fiber

    NASA Astrophysics Data System (ADS)

    Tokushima, Masatoshi; Ushida, Jun; Uemura, Toshinori; Kurata, Kazuhiko

    2015-09-01

    We present an optimized design of a shallow grating coupler in a silicon-on-insulator (SOI) wafer with a quadruple anti-reflection coating (ARC) of multiple layers of SiO2 and SiOxNy for coupling to a multimode fiber. The ARC is designed to generate sufficient destructive interference for downward emission while maintaining constructive interference for upward emission. We confirm numerically that the upward directionality of the grating is as high as -0.58 dB. Because the grating is shallow and the ARC is away from the SOI core layer, the back reflection along the input waveguide can be suppressed to -27 dB.

  2. Dual wavelength laser-induced damage threshold measurements of alumina/silica and hafnia/silica ultraviolet antireflective coatings.

    PubMed

    Mrohs, Marius; Jensen, Lars; Günster, Stefan; Alig, Thimotheus; Ristau, Detlev

    2016-01-01

    An approach for the measurement of the laser-induced damage threshold with two wavelengths combined was made while testing antireflective coatings for the wavelengths 266 and 532 nm. Samples were made of Al2O3/SiO2 and HfO2/SiO2 ion beam sputtered films. The results show that adding radiation of a second wavelength might lead to a significant reduction of the threshold. The damage morphology of single and dual wavelength tests is very similar and does not suggest an altered damage mechanism. Further investigations indicated that the dual wavelength threshold is a function of the temporal delay of the two pulses. PMID:26835628

  3. An abrasion-resistant and broadband antireflective silica coating by block copolymer assisted sol-gel method.

    PubMed

    Zou, Liping; Li, Xiaoguang; Zhang, Qinghua; Shen, Jun

    2014-09-01

    A double-layer broadband antireflective (AR) coating was prepared on glass substrate via sol-gel process using two kinds of acid-catalyzed TEOS-derived silica sols. The relative dense layer with a porosity of ∼10% was obtained from an as-prepared sol, while the porous layer with a porosity of ∼55% was from a modified one with block copolymer (BCP) Pluronic F127 as template which results in abundant ordered mesopores. The two layers give rise to a reasonable refractive index gradient from air to the substrate and thus high transmittance in a wide wavelength range, and both of them have the same tough skeleton despite different porosity, for which each single-layer and the double-layer coatings all behaved well in the mechanical property tests. The high transmittance and the strong ability of resisting abrasion make this coating promising for applications in some harsh conditions. In addition, the preparation is simple, low-cost, time-saving, and flexible for realizing the optical property. PMID:25117300

  4. Anti-reflection coatings on large area glass sheets. Final report, Motorola report No. 2366/4, DRD No. SE-5

    SciTech Connect

    Pastirik, E.

    1980-09-01

    Antireflective coatings which may be suitable for use on the covers of photovoltaic solar modules can be easily produced by a dipping process. The coatings are applied to glass by drawing sheets of glass vertically out of dilute aqueous sodium silicate solutions at a constant speed, allowing the adherent liquid film to dry, then exposing the dried film to concentrated sulfuric acid, followed by a water rinse and dry. The process produces coatings of good optical performance (96.7% peak transmission at 0.540 ..mu..M wavelength) combined with excellent stain and soil resistance, and good resistance to abrasion. The process is reproduceable and easily controlled.

  5. TiO2/Ni composite as antireflection coating for solar cell application

    NASA Astrophysics Data System (ADS)

    Haider, Adawiya J.; Najim, Aus A.; Muhi, Malik A. H.

    2016-07-01

    Titanium dioxide (TiO2) considered as one of the best material already used as a window in solar cells due to its antireflection capability. In this work, pure and Ni-doped (1, 3 and 5 wt%) TiO2 thin films were deposited using pulsed laser deposition (PLD) method. The optical measurements obtained by UV-vis indicate that the highest optical band gap was found with (5%) doping level (Eg=3.82 eV), corresponding to a lower reflectance and higher transmittance. Empirical equations between energy band gap and concentration level, reflectance with energy band gap, refractive index and concentration have been determined; a perfect fit with the experimental data was obtained.

  6. Films Consisting of Innumerable Tapered Nanopillars of Mesoporous Silica for Universal Antireflection Coatings.

    PubMed

    Miyata, Hirokatsu; Kitamura, Shin; Watanabe, Masatoshi; Takahashi, Masahiko

    2016-05-20

    Films with a fine structure consisting of innumerable nanopillars of mesoporous silica (MPS) are formed by a reactive ion etching process with a fluorine-containing gas. Each nanopillar has a tapered shape with a uniform height, which effectively suppresses reflection by the formation of an ideal graded refractive index structure. The nanopillars are spontaneously formed under low-pressure conditions, wherein locally deposited Al-F compounds, originating from an alumina plate in the etching chamber, work as a fine etching mask. The high etching rate of the MPS film allows a very high aspect ratio of the nanopillars. The refractive index of the MPS nanopillars can be universally tuned by a controlled incorporation of TiO2 into the mesopores, which results in effective reduction of reflectance on a given substrate. The outstanding antireflection performance is experimentally demonstrated for glass substrates with a wide refractive index range. PMID:27017295

  7. High efficiency antireflection coating in MWIR region (3.6-4.9 μm) simultaneously effective for Germanium and Silicon optics

    NASA Astrophysics Data System (ADS)

    Bhatt, Meenakshi; Nautiyal, B. B.; Bandyopadhyay, P. K.

    2010-01-01

    Antireflection coatings have critical importance in thermal imaging system working in MWIR region (3-5 μm) since optics of high refractive index materials are used. Germanium (Ge) and Silicon (Si) optics are used extensively in the MWIR thermal systems. In this paper a study has been carried out on the design and fabrication of multi-substrate antireflection coating effective for Germanium and Silicon optics in MWIR (3.6-4.9 μm) region. The wave band 3.6-4.9 μm is chosen for the reported work because detector system used in MWIR region has a band selection filter effective in the same wavelength region and atmospheric transmission window in MWIR region is effective in 3-5 μm spectral band. Comprehensive search method was used to design the multilayer stack on the substrate. The coating materials used in the design were Germanium (Ge), Hafnium oxide (HfO 2) and Y-Ba-Fluoride (IR-F625). The fabrication of coating was made in a coating plant fitted with Cryo pump system and residual gas analyzer (RGA). The evaporation was carried out at high vacuum (2-6 × 10 -6 mbar) with the help of electron beam gun system and layer thicknesses were measured with crystal monitor. The result achieved for the antireflection coating was 98.5% average transmission in 3.6-4.9 μm band for Germanium and Silicon optics. This work will be helpful in reducing the plant operation time, material and power consumption, as two different kinds of optics are simultaneously coated in a single coating cycle.

  8. Antireflection Coating Design for Series Interconnected Multi-Junction Solar Cells

    SciTech Connect

    AIKEN,DANIEL J.

    1999-11-29

    AR coating design for multi-junction solar cells can be more challenging than in the single junction case. Reasons for this are discussed. Analytical expressions used to optimize AR coatings for single junction solar cells are extended for use in monolithic, series interconnected multi-junction solar cell AR coating design. The result is an analytical expression which relates the solar cell performance (through J{sub SC}) directly to the AR coating design through the device reflectance. It is also illustrated how AR coating design can be used to provide an additional degree of freedom for current matching multi-junction devices.

  9. Enhancement of the Performance of GaAs based Solar Cells by using Plasmonic, Anti-Reflection Coating and Hydrophobic Effects

    NASA Astrophysics Data System (ADS)

    Makableh, Yahia F.

    Investigation of renewable energy resources is gaining huge momentum in recent years due to the limited fossil fuels, and their detriment impact on the environment. Solar energy is promising to meet the increased energy demand. In order to achieve this goal, solar energy has to be harvested efficiently at low cost. Therefore, higher efficiency solar cells are the primary focus of research worldwide. Photovoltaics based on InAs/GaAs intermediate band solar cells and their device performance enhancements are investigated in this dissertation. The device enhancement is carried out by surface modification methods. The dissertation work is inspired by the need of improved efficiency solar cells to meet the new energy demands. In this project, InAs/GaAs intermediate band solar cell and their device performance enhancement are investigated. The device enhancement is carried out though implementing surface modification by using plasmonic effect, anti-reflection coatings and self-cleaning surfaces. Single junction and quantum dots solar cells performance has been unsatisfying due to several optical losses especially high surface reflection. Hence, in this project, potential application of plasmonic effect and significant device performance enhancement implementing anti-reflection coating are studied experimentally. Significantly, GaAs based photovoltaics solar cells efficiencies were improved by 40 - 50 %. In addition, self-cleaning surfaces with contact angle above 156° has been achieved. This self-cleaning surface can ensure proper functionality of the anti-reflection coatings.

  10. Design and fabrication of multi-layers infrared antireflection coating consisting of ZnS and Ge on ZnS substrate

    NASA Astrophysics Data System (ADS)

    Zarei Moghadam, R.; Ahmadvand, H.; Jannesari, M.

    2016-03-01

    We have designed, fabricated and characterized a multi-layers antireflection coating on multispectral ZnS substrate, suitable for the infrared range of 8-12 μm. The 4-layers coating (Ge/ZnS/Ge/ZnS) with optimized thicknesses was fabricated by PVD technique and studied by FTIR, nanoindentation and AFM. From FTIR spectroscopy it was found that, in the wavelength range of 8-12 μm, the average transmittance of the double-side coated sample increases by about 26% and its maximum reaches about 98%. To improve the mechanical hardness, a bilayer of Y2O3/carbon was deposited on the coating. Nanoindentation test shows that the coating enhances the mechanical properties. The final coating have successfully passed durability and environmental tests.

  11. Sol-gel preparation of hydrophobic silica antireflective coatings with low refractive index by base/acid two-step catalysis.

    PubMed

    Cai, Shuang; Zhang, Yulu; Zhang, Hongli; Yan, Hongwei; Lv, Haibing; Jiang, Bo

    2014-07-23

    Hydrophobic antireflective coatings with a low refractive index were prepared via a base/acid-catalyzed two-step sol-gel process using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors, respectively. The base-catalyzed hydrolysis of TEOS leads to the formation of a sol with spherical silica particles in the first step. In the second step, the acid-catalyzed MTES hydrolysis and condensation occur at the surface of the initial base-catalyzed spherical silica particles, which enlarge the silica particle size from 12.9 to 35.0 nm. By a dip-coating process, this hybrid sol gives an antireflective coating with a refractive index of about 1.15. Moreover, the water contact angles of the resulted coatings increase from 22.4 to 108.7° with the increases of MTES content, which affords the coatings an excellent hydrophobicity. A "core-shell" particle growth mechanism of the hybrid sol was proposed and the relationship between the microstructure of silica sols and the properties of AR coatings was investigated. PMID:24979297

  12. Rapid replication and facile modulation of subwavelength antireflective polymer film using injection nanomolding and optical property of multilayer coatings

    NASA Astrophysics Data System (ADS)

    Fuh, Yiin-Kuen; Peng, Cheng-Chang; Huang, Chieh-Tse

    2013-10-01

    A rapid, cost-effective and high-throughput process for nanotexturing subwavelength structures with high uniformity using the polycarbonate (PC) is realized via injection nanomolding. The process enables the precise control of nanohole array (NHA) surface topography (nanohole depth, diameter, and periodicity) over large areas thereby presenting a highly versatile platform for fabricating substrates with user-defined, functional performance. Specifically, the optical property of the PC substrates were systematically characterized and tuned through the modulation of the depths of NHA. The aspect ratio submicron holes can be easily modulated and experimentally proven by simply adjusting the molding temperature. The nanotextured depths were reliably fabricated in the range of 200 to 400 nm with a period of approximately 700 nm. The fabricated PC films can reduce the reflectivity from an original bare film of 10.2% and 8.9% to 1.4% and 2.1% with 400-nm depth of nanoholes at the wavelength of 400 and 550 nm, respectively. Compared with conventional moth-like nanostructures with nanopillar arrays with heights adjustable only by an etching process, this paper proposes a facile route with submicron holes to achieve a similar antireflective function, with a significantly reduced time and facile height modulation capability. Furthermore, the effects of multilayer coatings of dielectric and metallic layers on the nanomolded NHA have been performed and potential sensing application is explored.

  13. Rapid replication and facile modulation of subwavelength antireflective polymer film using injection nanomolding and optical property of multilayer coatings

    PubMed Central

    2013-01-01

    A rapid, cost-effective and high-throughput process for nanotexturing subwavelength structures with high uniformity using the polycarbonate (PC) is realized via injection nanomolding. The process enables the precise control of nanohole array (NHA) surface topography (nanohole depth, diameter, and periodicity) over large areas thereby presenting a highly versatile platform for fabricating substrates with user-defined, functional performance. Specifically, the optical property of the PC substrates were systematically characterized and tuned through the modulation of the depths of NHA. The aspect ratio submicron holes can be easily modulated and experimentally proven by simply adjusting the molding temperature. The nanotextured depths were reliably fabricated in the range of 200 to 400 nm with a period of approximately 700 nm. The fabricated PC films can reduce the reflectivity from an original bare film of 10.2% and 8.9% to 1.4% and 2.1% with 400-nm depth of nanoholes at the wavelength of 400 and 550 nm, respectively. Compared with conventional moth-like nanostructures with nanopillar arrays with heights adjustable only by an etching process, this paper proposes a facile route with submicron holes to achieve a similar antireflective function, with a significantly reduced time and facile height modulation capability. Furthermore, the effects of multilayer coatings of dielectric and metallic layers on the nanomolded NHA have been performed and potential sensing application is explored. PMID:24088185

  14. Rapid replication and facile modulation of subwavelength antireflective polymer film using injection nanomolding and optical property of multilayer coatings.

    PubMed

    Fuh, Yiin-Kuen; Peng, Cheng-Chang; Huang, Chieh-Tse

    2013-01-01

    A rapid, cost-effective and high-throughput process for nanotexturing subwavelength structures with high uniformity using the polycarbonate (PC) is realized via injection nanomolding. The process enables the precise control of nanohole array (NHA) surface topography (nanohole depth, diameter, and periodicity) over large areas thereby presenting a highly versatile platform for fabricating substrates with user-defined, functional performance. Specifically, the optical property of the PC substrates were systematically characterized and tuned through the modulation of the depths of NHA. The aspect ratio submicron holes can be easily modulated and experimentally proven by simply adjusting the molding temperature. The nanotextured depths were reliably fabricated in the range of 200 to 400 nm with a period of approximately 700 nm. The fabricated PC films can reduce the reflectivity from an original bare film of 10.2% and 8.9% to 1.4% and 2.1% with 400-nm depth of nanoholes at the wavelength of 400 and 550 nm, respectively. Compared with conventional moth-like nanostructures with nanopillar arrays with heights adjustable only by an etching process, this paper proposes a facile route with submicron holes to achieve a similar antireflective function, with a significantly reduced time and facile height modulation capability. Furthermore, the effects of multilayer coatings of dielectric and metallic layers on the nanomolded NHA have been performed and potential sensing application is explored. PMID:24088185

  15. High-Quality Hollow Closed-Pore Silica Antireflection Coatings Based on Styrene-Acrylate Emulsion @ Organic-Inorganic Silica Precursor.

    PubMed

    Guo, Zhaolong; Zhao, Haixin; Zhao, Wei; Wang, Tao; Kong, Depeng; Chen, Taojing; Zhang, Xiaoyan

    2016-05-11

    Making use of a facile and low-cost way for the preparation of a hierarchically organized novel hollow closed-pore silica antireflective coating (CHAR) with tailored optical properties and a mechanical reliability is of great interest in the field of solar photovoltaic technology. The process mainly contains two aspects: (1) a styrene-acrylate emulsion @ organic-inorganic silica precursor (SA@OISP) core/shell hierarchical nanostructure, consisting of a sacrificial styrene-acrylate (SA) primary template, was fabricated using a sol-gel method; (2) the self-assembly of the nanostructures leads to SA@OISP nanospheres forming the high-quality hollow closed-pore silica antireflection coating (CHAR) by a dip-coating process and a subsequent calcination treatment. The resulting SA@OISP nanospheres have a mean diameter of 65.2 nm and contained a SA soft core with a mean diameter of approximately 54.8 nm and an organic-inorganic silica precursor (OISP) shell with a thickness of approximately 6-10 nm. Furthermore, the prepared CHAR film exhibited a high transmittance and good ruggedness. An average transmittance (TAV) of 97.64% was obtained, and the value is close to the ideal single-layered antireflection coating (98.09%) over a broad range of wavelengths (from 380 to 1100 nm). The CHAR film showed a stable TAV, with attenuation values of less than 0.8% and 0.43% after the abrasion test and the damp heat test, respectively. The conversion efficiency of the CHAR coating cover solar modules tends to be increased by 3.75%. The promising results obtained in this study suggest that the CHAR film was considered as an essential component of the solar module and were expected to provide additional solar energy harvest under extreme outdoor climates. PMID:27104837

  16. Broad Band Antireflection Coating on Zinc Sulphide Window for Shortwave infrared cum Night Vision System

    NASA Astrophysics Data System (ADS)

    Upadhyaya, A. S.; Bandyopadhyay, P. K.

    2012-11-01

    In state of art technology, integrated devices are widely used or their potential advantages. Common system reduces weight as well as total space covered by its various parts. In the state of art surveillance system integrated SWIR and night vision system used for more accurate identification of object. In this system a common optical window is used, which passes the radiation of both the regions, further both the spectral regions are separated in two channels. ZnS is a good choice for a common window, as it transmit both the region of interest, night vision (650 - 850 nm) as well as SWIR (0.9 - 1.7 μm). In this work a broad band anti reflection coating is developed on ZnS window to enhance the transmission. This seven layer coating is designed using flip flop design method. After getting the final design, some minor refinement is done, using simplex method. SiO2 and TiO2 coating material combination is used for this work. The coating is fabricated by physical vapour deposition process and the materials were evaporated by electron beam gun. Average transmission of both side coated substrate from 660 to 1700 nm is 95%. This coating also acts as contrast enhancement filter for night vision devices, as it reflect the region of 590 - 660 nm. Several trials have been conducted to check the coating repeatability, and it is observed that transmission variation in different trials is not very much and it is under the tolerance limit. The coating also passes environmental test for stability.

  17. Thermography and k-means clustering methods for anti-reflective coating film inspection: scratch and bubble defects

    NASA Astrophysics Data System (ADS)

    Zhou, Xunfei; Wang, Hongjin; Hsieh, Sheng-Jen (Tony)

    2016-05-01

    Anti-reflective coating is widely used on telescopes, eyeglasses and screens to effectively enhance the transmission of light. However, the presence of defects such as bubbles or scratches lowers the usability and functionality of optical film. Optical cameras are often used for coating inspection, but their accuracy relies heavily on the illumination source, camera viewing angles and defect location. This paper describes an active thermography approach that can potentially overcome this issue. Eighteen scratch and bubble defects were located on AR film with dimensions ranging from 0.03mm to 4.4 mm. An infrared camera was used to capture thermal images of those defects over 65 seconds of heating. After the thermal images were acquired, time-domain analysis and space-domain analysis were conducted and k-means clustering methodology was used to highlight the defective area. Results suggest active thermography can be used to detect scratch defects with widths of 0.03mm to 4.40 mm and bubble defects with diameters ranging from 0.08 to 4 mm. For defects with dimensions larger than 0.4 mm, our algorithm can estimate the dimension with less than 15% bias. However, for defects with dimensions less than 0.4mm, the algorithm estimation error ranged from 68% to 900% due to camera resolution limitations. It should be noted that our algorithm can still distinguish a scratch defect with a width of less than one pixel. This study also suggests active thermography can detect scratch and bubble defects regardless of the location of the illumination source.

  18. Perfect anti-reflection from first principles

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung-Ho; Q-Han Park

    2013-01-01

    Reducing unwanted reflections through impedance matching, called anti-reflection, has long been an important challenge in optics and electrical engineering. Beyond trial and error optimization, however, a systematic way to realize anti-reflection is still absent. Here, we report the discovery of an analytic solution to this long standing problem. For electromagnetic waves, we find the graded permittivity and permeability that completely remove any given impedance mismatch. We demonstrate that perfect broadband anti-reflection is possible when a dispersive, graded refractive index medium is used for the impedance-matching layer. We also present a design rule for the ultra-thin anti-reflection coating which we confirm experimentally by showing the anti-reflection behavior of an exemplary λ/25-thick coating made of metamaterials. This work opens a new path to anti-reflection applications in optoelectronic device, transmission line and stealth technologies.

  19. Antireflection coating on germanium for dual channel (3-5 and 7.5-10.6 μm) thermal imagers

    NASA Astrophysics Data System (ADS)

    Ghosh, A.; Kant, P.; Bandyopadhyay, P. K.; Chandra, P.; Nijhawan, O. P.

    1999-02-01

    The dual channel thermal imager, operating in the 3-5 and 7.5-10.6 μm wavelength bands, is one of the latest achievements in instrumentation for target recognition and acquisition. While the 3-5 μm band is utilised for detecting hot objects such as engine exhausts of vehicles and fighter planes, the 7.5-10.6 μm band is employed for human bodies and objects at ambient temperatures. Many substrates are available which transmit in both these wavelength bands and their transmission can be enhanced by providing a suitable antireflection coating. In this paper, a broad band antireflection coating on germanium substrate is reported. The design approach involves achieving a continuously varying refractive index from that of the incident medium to the substrate. The continuously varying refractive index profile may be generated by using a sequence of thin layers of high and low refractive index materials. In this design a continuous refractive index profile is approximated by using a 13-layer stack of thorium fluoride and germanium as low and high index coating materials respectively. This coating conforms to environmental stability standards and shows an average transmission of 91% in 3-5 μm band and 94.5% in 7.5-10.6 μm band with a peak of 97% at 9 μm on 10 mm thick germanium substrate. Polycrystalline germanium has 2.5% absorption for a 10 mm thick substrate.

  20. Ultraporous nanocrystalline TiO2-based films: synthesis, patterning and application as anti-reflective, self-cleaning, superhydrophilic coatings

    NASA Astrophysics Data System (ADS)

    Faustini, Marco; Grenier, Antonin; Naudin, Guillaume; Li, Ronghua; Grosso, David

    2015-11-01

    Crack-free, anatase-based optical coatings with a refractive index down to 1.27, a porosity up to 80 vol%, and a tunable thickness up to 1.5 μm were fabricated. The extraordinary stability of the porosity upon thermally induced crystallisation and template removal was attributed to the combined effects of the presence of 10% molar silica in the inorganic phase, a flash treatment at 500 °C, and the use of templates with different dimensions ranging from a few nanometers to 50 nm. The hierarchical porous system was directly patterned by UV lithography and used as multifunctional anti-reflective, self-cleaning coatings.Crack-free, anatase-based optical coatings with a refractive index down to 1.27, a porosity up to 80 vol%, and a tunable thickness up to 1.5 μm were fabricated. The extraordinary stability of the porosity upon thermally induced crystallisation and template removal was attributed to the combined effects of the presence of 10% molar silica in the inorganic phase, a flash treatment at 500 °C, and the use of templates with different dimensions ranging from a few nanometers to 50 nm. The hierarchical porous system was directly patterned by UV lithography and used as multifunctional anti-reflective, self-cleaning coatings. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06466j

  1. An Evaluation of Atmospheric-pressure Plasma for the Cost-Effective Deposition of Antireflection Coatings

    SciTech Connect

    Rob Sailer; Guruvenket Srinivasan; Kyle W. Johnson; Douglas L. Schulz

    2010-04-01

    Atmospheric-pressure plasma deposition (APPD) has previously been used to deposit various functional materials including polymeric surface modification layers, transparent conducting oxides, and photo catalytic materials. For many plasma polymerized coatings, reaction occurs via free radical mechanism where the high energy electrons from the plasma activate the olefinic carbon-carbon double bonds - a typical functional group in such precursors. The precursors for such systems are typically inexpensive and readily available and have been used in vacuum PECVD previously. The objectives are to investigate: (1) the effect of plasma power, gas composition and substrate temperature on the Si-based film properties using triethylsilane(TES) as the precursor; and (2) the chemical, mechanical, and optical properties of several experimental matrices based on Design of Experiment (DOE) principals. A simple APPD route has been utilized to deposit Si based films from an inexpensive precursor - Triethylsilane (TES). Preliminary results indicates formation of Si-C & Si-O and Si-O, Si-C & Si-N bonds with oxygen and nitrogen plasmas respectively. N{sub 2}-O{sub 2} plasma showed mixed trend; however oxygen remains a significant portion of all films, despite attempts to minimize exposure to atmosphere. SiN, SiC, and SiO ratios can be modified by the reaction conditions resulting in differing film properties. SE studies revealed that films with SiN bond possess refractive index higher than coatings with Si-O/Si-C bonds. Variable angle reflectance studies showed that SiOCN coatings offer AR properties; however thickness and refractive index optimization of these coatings remains necessary for application as potential AR coatings.

  2. Preparation and stress evolution of sol-gel SiO2 antireflective coatings for small-size anisotropic lithium triborate crystals

    NASA Astrophysics Data System (ADS)

    Tian, Bingtao; Wang, Xiaodong; Niu, Yanyan; Zhang, Jinlong; Zhang, Qinghua; Zhang, Zhihua; Wu, Guangming; Zhou, Bin; Shen, Jun

    2016-04-01

    Lithium triborate (LiB3O5, LBO) crystal is now one of the most useful nonlinear optical materials for frequency conversion of high power lasers. The use of the crystal, however, has been hampered by the unavailability of antireflective (AR) coatings with high laser damage resistance. In this work, a "point contact" dip-coating method is developed to prepare sol-gel SiO2 AR coatings on small-size LBO crystals. Using this approach, we obtain a homogenous coating surface on an 8 mm×8 mm×3 mm LBO crystal. The stress measurements show that the stresses in sol-gel SiO2 coatings vary with the time of natural drying, which is beyond our expectation. The anisotropic Young's modulus of the LBO crystal and the different evolution tendency of the stress in the different SiO2 coating layers are found to be responsible for the crack of the double-layer AR coatings on anisotropic LBO crystal. Meanwhile, the resulting coatings on LBO crystal achieve a LIDT of over 15 J/cm2 (532 nm, 3ns) and the coated LBO is expected to have a transmittance of over 99% at 800 nm.

  3. Radiation sensitive developable bottom anti-reflective coatings (DBARC) for 193nm lithography: first generation

    NASA Astrophysics Data System (ADS)

    Toukhy, Medhat; Oberlander, Joseph; Mullen, Salem; Lu, PingHung; Neisser, Mark

    2007-03-01

    A first generation DBARC applicable for 1 st minimum 193nm lithography is described in this paper. The polymer used in this DBARC is insoluble in the casting solvent of the resist, which is propyleneglycolmonomethyletheracetate (PGMEA). Photo acid generator (PAG) and base extractions from the DBARC coating by the resist casting solvent were examined by the DBARC dissolution rates in the developer, before and after solvent treatments. Although the resist and the DBARC do not appear to intermix, strong interaction between the two is evident by their lithographic performance and dissolution rate study.

  4. Optimal design and fabrication method for antireflection coatings for P-polarized 193 nm laser beam at large angles of incidence (68°-74°).

    PubMed

    Jin, Jingcheng; Jin, Chunshui; Li, Chun; Deng, Wenyuan; Chang, Yanhe

    2013-09-01

    Most of the optical axes in modern systems are bent for optomechanical considerations. Antireflection (AR) coatings for polarized light at oblique incidence are widely used in optical surfaces like prisms or multiform lenses to suppress undesirable reflections. The optimal design and fabrication method for AR coatings with large-angle range (68°-74°) for a P-polarized 193 nm laser beam is discussed in detail. Experimental results showed that after coating, the reflection loss of a P-polarized laser beam at large angles of incidence on the optical surfaces is reduced dramatically, which could greatly improve the output efficiency of the optical components in the deep ultraviolet vacuum range. PMID:24323257

  5. Composite films prepared by plasma ion-assisted deposition (IAD) for design and fabrication of antireflection coatings in visible and near-infrared spectral regions

    NASA Astrophysics Data System (ADS)

    Tsai, Rung-Ywan; Ho, Fang C.

    1994-11-01

    Ion-assisted deposition (IAD) processes configured with a well-controlled plasma source at the center base of a vacuum chamber, which accommodates two independent e-gun sources, is used to deposition TiO2MgF2 and TiO2-SiO2 composite films of selected component ratios. Films prepared by this technology are found durable, uniform, and nonabsorbing in visible and near-IR regions. Single- and multilayer antireflection coatings with refractive index from 1.38 to 2.36 at (lambda) equals 550 nm are presented. Methods of enhancement in optical performance of these coatings are studied. The advantages of AR coatings formed by TiO2-MgF2 composite films over those similar systems consisting of TiO2-SiO2 composite films in both visible and near-IR regions are also presented.

  6. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-12-01

    We have examined how three different cleaning processes affect the laser-induced damage threshold (LIDT) of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. Coatings that received cleaning exhibited the highest LIDTs compared to coatings that were not cleaned. In some cases, there is nearly a twofold increase in the LIDT between the cleaned and uncleaned coatings (19.4 J/cm2 compared to 39.1 J/cm2). Higher LIDTs were realized after 4 months of aging. The most effective cleaning process involved washing the coated surface with mild detergent, and then soaking the optic in a mixture of ethyl alcohol and deionized water. Also, the laser damage results indicate that the presence of nonpropagating (NP) damage sites dominates the LIDTs of almost every optic, despite the cleaning process used. NP damage sites can be attributed to defects such as nodules in the coating or surface contamination, which suggests that pursuing further improvements to the deposition or cleaning processes are worthwhile to achieve even higher LIDTs.

  7. Optical and mechanical behavior of GeC and BP antireflection coatings under rain erosion tests

    NASA Astrophysics Data System (ADS)

    Mackowski, Jean-Marie; Cimma, B.; Lacuve, J.; Laprat, Patrice

    1994-09-01

    Thick germanium carbide (GeC) and boron phosphide (BP) films are successfully grown on various zinc sulfide and germanium substrates at temperatures up to 450 degree(s)C by reactive radio-frequency sputtering (RRFS). The sputtering conditions are respectively a germanium target within a medium of methane-argon for GeC films and a high density boron target in a sputtering medium of phosphine-argon for BP films. The rain erosion resistance of GeC and BP films protected or not by diamond-like carbon (DLC) coating on top are measured for water drop diameter of 1.2 mm or 2 mm with an impact velocity ranging from 210 m/s to 265 m/s on the Saab-Scania whirling-arm rig facilities (Linkoping, Sweden). Rain erosion resistance of BP films for a wavelength band in the 8 micrometers to 10 micrometers range shows no damage for a speed up to 250 m/s with an exposure time up to 10 min, whereas the GeC rain erosion resistance shows no damage up to 235 m/s for the same exposure time. The transmission of each film is well correlated to its optical absorption at 10.6 micrometers . The GeC absorption can be reduced down to 40 cm-1 whereas the BP absorption stays around 220 cm-1 for sputtered films. So the compromise between the optical performance and the rain erosion resistance can be achieved by the use of GeC or BP films.

  8. Performance enhancement of plasmonics silicon solar cells using Al2O3/In NPs/TiO2 antireflective surface coating

    NASA Astrophysics Data System (ADS)

    Ho, Wen-Jeng; Lee, Yi-Yu; Lin, Chi-He; Yeh, Chien-Wu

    2015-11-01

    In this study, the enhancement of silicon solar cell photovoltaic performance by means of indium nanoparticles (In NPs) deposited on the TiO2 space layer and capped with an Al2O3 antireflective layer is demonstrated. The impressive performance enhancement is attributed to the plasmonic scattering of broadband light which occurs as a result of the Al2O3/In NPs/TiO2 antireflective coating (PARC) surface structure. The optical reflectance, photovoltaic current-voltage (I-V), external quantum efficiency (EQE), and photovoltaic performance as a function of the incident angles are measured and compared. The experimental results show that the reflectance decreases with increasing TiO2 thickness and that the lowest reflection point of the spectrum was red-shifted by the use of a PARC surface structure. EQE was significantly enhanced between 400 and 1050 nm wavelengths and much high EQE of 85% were observed for the cell with In NPs embedded in the 65-nm Al2O3/20 nm TiO2 layer structure. In comparison to a bare reference solar cell, an efficiency enhancement of 54.47% (from 10.96% to 16.93%) and a short-circuit current density enhancement of 52.83% (from 26.10 to 39.89 mA/cm2) were obtained for the cell with a 65-nm Al2O3/In NPs/20-nm TiO2 antireflection structure under normal incident illumination. In addition, for incident angles from 0° to 15°, the 0.78% decrease in conversion efficiency (from 16.71% to 16.58%) of the cell with the PARC surface structure was less than the 3.28% (from 13.86% to 13.49%) decrease of the cell with 65-nm Al2O3/20-nm TiO2 double layer antireflective coating (DL-ARC) due to the plasmonic scattering of broadband light.

  9. Effects of the chemical bonding on the optical and mechanical properties for germanium carbide films used as antireflection and protection coating of ZnS windows

    NASA Astrophysics Data System (ADS)

    Hu, Chaoquan; Zheng, Weitao; Tian, Hongwei; LeXu; Jiang, Qing

    2006-05-01

    Germanium carbide (Ge1-xCx) films have been prepared by RF reactive sputtering a pure Ge(111) target at different flow rate ratios of CH4/(CH4+Ar) in a CH4/Ar mixture discharge, and it has been found that the composition, chemical bonding, optical and mechanical properties of Ge1-xCx films are remarkably influenced by the flow rate ratio of CH4/(CH4+Ar). The effects of the chemical bonding on the optical and mechanical properties of the Ge1-xCx films have been explored. In addition, an antireflection Ge1-xCx double-layer coating deposited on both sides of the ZnS substrate wafer has been developed for application as an infrared window. It is shown that the transmittance in the wavelength region between 8 and 12 µm and the hardness of the ZnS substrate have been significantly improved by the double-layer coating.

  10. Efficiency enhancement of non-selenized Cu(In,Ga)Se2 solar cells employing scalable low-cost antireflective coating

    PubMed Central

    2014-01-01

    In this study, a non-selenized CuInGaSe2 (CIGS) solar device with textured zinc oxide (ZnO) antireflection coatings was studied. The ZnO nanostructure was fabricated by a low-temperature aqueous solution deposition method. With controlling the morphology of the solution-grown tapered ZnO nanorod coatings, the average reflectance of the CIGS solar device decreased from 8.6% to 2.1%, and the energy conversion efficiency increased from 9.1% to 11.1%. The performance improvement in the CuInGaSe2 thin-film solar cell was well explained due to the gradual increase of the refractive index between air and the top electrode of solar cell device by the insertion of the ZnO nanostructure. The results demonstrate a potential application of the ZnO nanostructure array for efficient solar device technology. PMID:25114632

  11. Ultraporous nanocrystalline TiO2-based films: synthesis, patterning and application as anti-reflective, self-cleaning, superhydrophilic coatings.

    PubMed

    Faustini, Marco; Grenier, Antonin; Naudin, Guillaume; Li, Ronghua; Grosso, David

    2015-12-14

    Crack-free, anatase-based optical coatings with a refractive index down to 1.27, a porosity up to 80 vol%, and a tunable thickness up to 1.5 μm were fabricated. The extraordinary stability of the porosity upon thermally induced crystallisation and template removal was attributed to the combined effects of the presence of 10% molar silica in the inorganic phase, a flash treatment at 500 °C, and the use of templates with different dimensions ranging from a few nanometers to 50 nm. The hierarchical porous system was directly patterned by UV lithography and used as multifunctional anti-reflective, self-cleaning coatings. PMID:26549535

  12. The impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-09-01

    The Z-Backlighter lasers at Sandia National Laboratories are kilojoule class, pulsed systems operating with ns pulse lengths at 527 nm and ns and sub-ps pulse lengths at 1054 nm (www.z-beamlet.sandia.gov), and are linked to the most powerful and energetic x-ray source in the world, the Z-Accelerator (http://www.sandia.gov/z-machine/). An important Z-Backlighter optic is a flat, fused silica optic measuring 32.5 cm × 32.5 cm × 1 cm with an antireflection (AR) coating on both sides. It is used as a debris shield to protect other Z-Backlighter laser optics from high-velocity particles released by the experiments conducted in the Z-Accelerator. Each experiment conducted in the Z-Accelerator releases enough debris to cloud the surface of a debris shield, which means that a debris shield cannot be used for more than one experiment. Every year, the large optics coating facility [1] at Sandia provides AR coatings for approximately 50 debris shields, in addition to AR coatings for numerous other meter-class Z-Backlighter lenses and windows. As with all Z-Backlighter optical coatings, these AR coatings must have a high laser-induced damage threshold (LIDT) in order to withstand the powerful Z-Backlighter laser fluences. Achieving a good LIDT depends not only on the coating deposition processes but also on the polishing and cleaning processes used to prepare the coated and uncoated surfaces [2]. We spend a lot of time, both before and after the coatings have been deposited, manually cleaning the optics, including the debris shields, even though they are an expendable type of optic. Therefore, in this study we have tested new cleaning methods in addition to our current method to determine their impact on the LIDT of AR coatings, and conclude whether a shorter-duration or less labor-intensive cleaning process would suffice.

  13. How reduced vacuum pumping capability in a coating chamber affects the laser damage resistance of HfO2/SiO2 antireflection and high-reflection coatings

    NASA Astrophysics Data System (ADS)

    Field, Ella S.; Bellum, John C.; Kletecka, Damon E.

    2015-11-01

    Optical coatings with the highest laser damage thresholds rely on clean conditions in the vacuum chamber during the coating deposition process. A low base pressure in the coating chamber, as well as the ability of the vacuum system to maintain the required pressure during deposition, are important aspects of limiting the amount of defects in an optical coating that could induce laser damage. Our large optics coating chamber at Sandia National Laboratories normally relies on three cryo pumps to maintain low pressures for e-beam coating processes. However, on occasion, one or more of the cryo pumps have been out of commission. In light of this circumstance, we decided to explore how deposition under compromised vacuum conditions resulting from the use of only one or two cryo pumps affects the laser-induced damage thresholds of optical coatings. The coatings of this study consist of HfO2 and SiO2 layer materials and include antireflection coatings for 527 nm at normal incidence, and high reflection coatings for 527 nm, 45° angle of incidence (AOI), in P-polarization (P-pol).

  14. Antireflection Coatings 1: BASICS

    SciTech Connect

    Martin, Peter M.

    2005-11-15

    Reflections off windows, eyeglass lenses, computer and television screens, and optical components can be very annoying and sometimes dangerous. Reflection of light incident on an optical window or optical component can degrade the performance of the window and the optical system associated with the window over its operating spectral range, whether it is the human eye or an optical device. Thin films can help us with this problem.

  15. Omnidirectional wavelength selective emitters/absorbers based on dielectric-filled anti-reflection coated two-dimensional metallic photonic crystals

    NASA Astrophysics Data System (ADS)

    Yeng, Yi Xiang; Chou, Jeffrey B.; Rinnerbauer, Veronika; Shen, Yichen; Kim, Sang-Gook; Joannopoulos, John D.; Soljačić, Marin; Čelanović, Ivan

    2014-08-01

    We demonstrate designs of dielectric-filled anti-reflection coated (ARC) two-dimensional (2D) metallic photonic crystals (MPhCs) capable of omnidirectional, polarization insensitive, wavelength selective emission/absorption. Up to 26% improvement in hemispherically averaged emittance/absorptance below the cutoff wavelength is observed for optimized hafnium oxide filled 2D tantalum (Ta) PhCs over the unfilled 2D Ta PhCs. The optimized designs possess high hemispherically averaged emittance/absorptance of 0.86 at wavelengths below the cutoff wavelength and low hemispherically averaged emittance/absorptance of 0.12 at wavelengths above the cutoff wavelength, which is extremely promising for applications such as thermophotovoltaic energy conversion, solar absorption, and infrared spectroscopy.

  16. The Mercury Laser System: An Average power, gas-cooled, Yb:S-FAP based system with frequency conversion and wavefront correction

    SciTech Connect

    Bibeau, C; Bayramian, A; Armstrong, P; Ault, E; Beach, R; Benapfl, M; Campbell, R; Dawson, J; Ebbers, C; Freitas, B; Kent, R; Liao, Z; Ladran, T; Menapace, J; Molander, B; Moses, E; Oberhelman, S; Payne, S; Peterson, N; Schaffers, K; Stolz, C; Sutton, S; Tassano, J; Telford, S; Utterback, E; Randles, M

    2005-08-31

    We report on the operation of the Mercury laser with fourteen 4 x 6 cm{sup 2} Yb:S-FAP amplifier slabs pumped by eight 100 kW peak power diode arrays. The system was continuously run at 55 J and 10 Hz for several hours, (2 x 10{sup 5} cumulative shots) with over 80% of the energy in a 6 times diffraction limited spot at 1.047 um. Improved optical quality was achieved in Yb:S-FAP amplifiers with magneto-rheological finishing, a deterministic polishing method. In addition, average power frequency conversion employing YCOB was demonstrated at 50% conversion efficiency or 22.6 J at 10 Hz.

  17. Effects of the chemical bonding on the optical and mechanical properties for germanium carbide films used as antireflection and protection coating of ZnS windows.

    PubMed

    Hu, Chaoquan; Zheng, Weitao; Tian, Hongwei; Xu, Le; Jiang, Qing

    2006-05-01

    Germanium carbide (Ge(1-x)C(x)) films have been prepared by RF reactive sputtering a pure Ge(111) target at different flow rate ratios of CH(4)/(CH(4)+Ar) in a CH(4)/Ar mixture discharge, and it has been found that the composition, chemical bonding, optical and mechanical properties of Ge(1-x)C(x) films are remarkably influenced by the flow rate ratio of CH(4)/(CH(4)+Ar). The effects of the chemical bonding on the optical and mechanical properties of the Ge(1-x)C(x) films have been explored. In addition, an antireflection Ge(1-x)C(x) double-layer coating deposited on both sides of the ZnS substrate wafer has been developed for application as an infrared window. It is shown that the transmittance in the wavelength region between 8 and 12 µm and the hardness of the ZnS substrate have been significantly improved by the double-layer coating. PMID:21690777

  18. Design of a Three-Layer Antireflection Coating for High Efficiency Indium Phosphide Solar Cells Using a Chemical Oxide as First Layer

    NASA Technical Reports Server (NTRS)

    Moulot, Jacques; Faur, Mircea; Faur, Maria; Goradia, Chandra; Goradia, Manju; Bailey, Sheila

    1995-01-01

    It is well known that the behavior of III-V compound based solar cells is largely controlled by their surface, since the majority of light generated carriers (63% for GaAs and 79% for InP) are created within 0.2 microns of the illuminated surface of the cell. Consequently, the always observed high surface recombination velocity (SRV) on these cells is a serious limiting factor for their high efficiency performance, especially for those with the p-n junction made by either thermal diffusion or ion implantation. A good surface passivation layer, ideally, a grown oxide as opposed to a deposited one, will cause a significant reduction in the SRV without adding interface problems, thus improving the performance of III-V compound based solar cells. Another significant benefit to the overall performance of the solar cells can be achieved by a substantial reduction of their large surface optical reflection by the use of a well designed antireflection (AR) coating. In this paper, we demonstrate the effectiveness of using a chemically grown, thermally and chemically stable oxide, not only for surface passivation but also as an integral part of a 3- layer AR coating for thermally diffused p(+)n InP solar cells. A phosphorus-rich interfacial oxide, In(PO3)3, is grown at the surface of the p(+) emitter using an etchant based on HNO3, o-H3PO4 and H2O2. This oxide has the unique properties of passivating the surface as well as serving as a fairly efficient antireflective layer yielding a measured record high AM0, 25 C, open-circuit voltage of 890.3 mV on a thermally diffused InP(Cd,S) solar cell. Unlike conventional single layer AR coatings such as ZnS, Sb2O3, SiO or double layer AR coatings such as ZnS/MgF2 deposited by e-beam or resistive evaporation, this oxide preserves the stoichiometry of the InP surface. We show that it is possible to design a three-layer AR coating for a thermally diffused InP solar cell using the In(PO3)3 grown oxide as the first layer and Al2O3, MgF2 or

  19. Design of a three-layer antireflection coating for high efficiency indium phosphide solar cells using a chemical oxide as first layer

    NASA Technical Reports Server (NTRS)

    Moulot, Jacques; Faur, M.; Faur, M.; Goradia, C.; Goradia, M.; Bailey, S.

    1995-01-01

    It is well known that the behavior of III-V compound based solar cells is largely controlled by their surface, since the majority of light generated carriers (63% for GaAs and 79% for InP) are created within 0.2 mu m of the surface of the illuminated cell. Consequently, the always observed high surface recombination velocity (SRV) on these cells is a serious limiting factor for their high efficiency performance, especially for those with p-n junction made by either thermal diffusion or ion implantation. A good surface passivation layer, ideally a grown oxide as opposed to a deposited one, will cause a significant reduction in the SRV without adding interface problems, thus improving the performance of III-V compound based solar cells. Another significant benefit to the overall performance of the solar cells can be achieved by a substantial reduction of their large surface optical reflection by the use of a well designed antireflection (AR) coating. In this paper, we demonstrate the effectiveness of using a chemically grown thermally and chemically stable oxide, not only for surface passivation but also as an integral part of a 3-layer AR coating for thermally diffused p+n InP solar cells. A phosphorus-rich interfacial oxide, In(PO3)3, is grown at the surface of the p+ emitter using an etchant based on HNO3, o-H3PO4 and H2O2. This oxide has the unique properties of passivating the surface as well as serving as an efficient antireflective layer yielding a measured record high AMO open-circuit voltage of 890.3 mV on a thermally diffused InP(Cd,S) solar cell. Unlike conventional single layer AR coatings such as ZnS, Sb2O3, SiO or double layer AR coatings such as ZnS/MgF2 deposited by e-beam or resistive evaporation, this oxide preserves the stoichiometry of the InP surface. We show that it is possible to design a three-layer AR coating for a thermally diffused InP solar cell using the In(PO3)3 grown oxide as the first layer and Al2O3 and MgF2 as the second and third

  20. A novel method for crystalline silicon solar cells with low contact resistance and antireflection coating by an oxidized Mg layer

    PubMed Central

    2012-01-01

    One of the key issues in the solar industry is lowering dopant concentration of emitter for high-efficiency crystalline solar cells. However, it is well known that a low surface concentration of dopants results in poor contact formation between the front Ag electrode and the n-layer of Si. In this paper, an evaporated Mg layer is used to reduce series resistance of c-Si solar cells. A layer of Mg metal is deposited on a lightly doped n-type Si emitter by evaporation. Ag electrode is screen printed to collect the generated electrons. Small work function difference between Mg and n-type silicon reduces the contact resistance. During a co-firing process, Mg is oxidized, and the oxidized layer serves as an antireflection layer. The measurement of an Ag/Mg/n-Si solar cell shows that Voc, Jsc, FF, and efficiency are 602 mV, 36.9 mA/cm2, 80.1%, and 17.75%, respectively. It can be applied to the manufacturing of low-cost, simple, and high-efficiency solar cells. PMID:22221405

  1. ECR CVD of silicon oxynitride films for antireflection coating of 10 Gbit/s, 1.56 {micro}m multi-quantum well InP/InGaAsP Mach-Zehnder modulators

    SciTech Connect

    Rousina-Webb, R.; Dzioba, S.; Gallant, M.; Raine, L.; Tong, R.; Rolland, C.

    1996-12-31

    This paper describes the development of electron cyclotron resonance (ECR) plasma-deposited SiO{sub x}N{sub y} single layer anti-reflecting (AR) optical coatings for III-V 10 Gbit/s, 1.56 {micro}m Mach-Zehnder (MZ) modulators. In this paper the authors report of the fabrication and characterization of SiO{sub x}N{sub y} films deposited by ECR CVD which provides low ion energy ({approximately} < 25 eV) bombardment, low plasma damage and low deposition temperature to produce high quality, stable AR facet coatings.

  2. Measurements and simulations of the optical gain and anti-reflection coating modal reflectivity in quantum cascade lasers with multiple active region stacks

    NASA Astrophysics Data System (ADS)

    Bidaux, Y.; Terazzi, R.; Bismuto, A.; Gresch, T.; Blaser, S.; Muller, A.; Faist, J.

    2015-09-01

    We report spectrally resolved gain measurements and simulations for quantum cascade lasers (QCLs) composed of multiple heterogeneous stacks designed for broadband emission in the mid-infrared. The measurement method is first demonstrated on a reference single active region QCL based on a double-phonon resonance design emitting at 7.8 μm. It is then extended to a three-stack active region based on bound-to-continuum designs with a broadband emission range from 7.5 to 10.5 μm. A tight agreement is found with simulations based on a density matrix model. The latter implements exhaustive microscopic scattering and dephasing sources with virtually no fitting parameters. The quantitative agreement is furthermore assessed by measuring gain coefficients obtained by studying the threshold current dependence with the cavity length. These results are particularly relevant to understand fundamental gain mechanisms in complex semiconductor heterostructure QCLs and to move towards efficient gain engineering. Finally, the method is extended to the measurement of the modal reflectivity of an anti-reflection coating deposited on the front facet of the broadband QCL.

  3. Silicon nitride anti-reflection coating on the glass and transparent conductive oxide interface for thin film solar cells and modules

    NASA Astrophysics Data System (ADS)

    Iwahashi, T.; Morishima, M.; Fujibayashi, T.; Yang, R.; Lin, J.; Matsunaga, D.

    2015-10-01

    Anti-reflection coating (ARC) is well known as an important technique to enhance solar cell performance. Typical ARC has been applied on the glass surface to reduce light reflection loss at the air/glass interface. However, reflection loss occurs not only at glass surface but also at other interfaces such as glass/transparent conductive oxide (TCO) interface. The refractive index of SiNx is tunable from 1.6 to 2.7, and the range from 1.7 to 2.0 is suitable for ARC at glass/TCO interface. In this study, we examined the AR effect of silicon nitride (SiNx) deposited by plasma enhanced chemical vapor deposition at the glass/TCO interface with thin film silicon solar cell and module. Reflectivity reduction of 1.6% for glass/ZnO substrate has been obtained with optimal SiNx layer, which contribute 2.0% gain in cell efficiency. Besides, we also confirmed the relative efficiency gain of around 2% for large-sized solar module, leading to a world-record large area stabilized module conversion efficiency of 12.34%.

  4. Measurements and simulations of the optical gain and anti-reflection coating modal reflectivity in quantum cascade lasers with multiple active region stacks

    SciTech Connect

    Bidaux, Y.; Terazzi, R.; Bismuto, A.; Gresch, T.; Blaser, S.; Muller, A.; Faist, J.

    2015-09-07

    We report spectrally resolved gain measurements and simulations for quantum cascade lasers (QCLs) composed of multiple heterogeneous stacks designed for broadband emission in the mid-infrared. The measurement method is first demonstrated on a reference single active region QCL based on a double-phonon resonance design emitting at 7.8 μm. It is then extended to a three-stack active region based on bound-to-continuum designs with a broadband emission range from 7.5 to 10.5 μm. A tight agreement is found with simulations based on a density matrix model. The latter implements exhaustive microscopic scattering and dephasing sources with virtually no fitting parameters. The quantitative agreement is furthermore assessed by measuring gain coefficients obtained by studying the threshold current dependence with the cavity length. These results are particularly relevant to understand fundamental gain mechanisms in complex semiconductor heterostructure QCLs and to move towards efficient gain engineering. Finally, the method is extended to the measurement of the modal reflectivity of an anti-reflection coating deposited on the front facet of the broadband QCL.

  5. Fabrication and characterization of silicon wire solar cells having ZnO nanorod antireflection coating on Al-doped ZnO seed layer

    PubMed Central

    2012-01-01

    In this study, we have fabricated and characterized the silicon [Si] wire solar cells with conformal ZnO nanorod antireflection coating [ARC] grown on a Al-doped ZnO [AZO] seed layer. Vertically aligned Si wire arrays were fabricated by electrochemical etching and, the p-n junction was prepared by spin-on dopant diffusion method. Hydrothermal growth of the ZnO nanorods was followed by AZO film deposition on high aspect ratio Si microwire arrays by atomic layer deposition [ALD]. The introduction of an ALD-deposited AZO film on Si wire arrays not only helps to create the ZnO nanorod arrays, but also has a strong impact on the reduction of surface recombination. The reflectance spectra show that ZnO nanorods were used as an efficient ARC to enhance light absorption by multiple scattering. Also, from the current-voltage results, we found that the combination of the AZO film and ZnO nanorods on Si wire solar cells leads to an increased power conversion efficiency by more than 27% compared to the cells without it. PMID:22222067

  6. Improvement in light harvesting of dye-sensitized solar cells with antireflective and hydrophobic textile PDMS coating by facile soft imprint lithography.

    PubMed

    Lim, Joo Ho; Ko, Yeong Hwan; Leem, Jung Woo; Yu, Jae Su

    2015-02-01

    We demonstrated the improved conversion efficiency (η) of dye-sensitized solar cells (DSSCs) using the textile-patterned polydimethylsiloxane (PDMS) antireflection layers prepared by metal-coated textile master molds by a simple soft imprint lithography. When light propagates through the textile-patterned surface of PDMS (i.e., textile PDMS) laminated on the outer glass surface deposited with fluorine-doped tin oxide (i.e., FTO/glass), both the transmitted and diffused lights into the photo-anode of DSSCs were simultaneously enhanced. Compared to the bare FTO/glass, the textile PDMS increased the total transmittance from 82.3 to 85.1% and its diffuse transmittance was significantly increased from 5.9 to 78.1% at 550 nm of wavelength. The optical property of textile PDMS was also theoretically analyzed by the finite-difference time-domain simulation. By laminating the textile PDMS onto the outer glass surface of DSSCs, the η was enhanced from 6.04 to 6.51%. Additionally, the fabricated textile PDMS exhibited a hydrophobic surface with water contact angle of ~123.15°. PMID:25836246

  7. Defect Band Luminescence Intensity Reversal as Related to Application of Anti-Reflection Coating on mc-Si PV Cells: Preprint

    SciTech Connect

    Guthrey, H.; Johnston, S.; Yan, F.; Gorman, B.; Al-Jassim, M.

    2012-06-01

    Photoluminescence (PL) imaging is widely used to identify defective regions within mc-Si PV cells. Recent PL imaging investigations of defect band luminescence (DBL) in mc-Si have revealed a perplexing phenomenon. Namely, the reversal of the DBL intensity in various regions of mc-Si PV material upon the application of a SiNx:H anti-reflective coating (ARC). Regions with low DBL intensity before ARC application often exhibit high DBL intensity afterwards, and the converse is also true. PL imaging alone cannot explain this effect. We have used high resolution cathodoluminescence (CL) spectroscopy and electron beam induced current (EBIC) techniques to elucidate the origin of the DBL intensity reversal. Multiple sub-bandgap energy levels were identified that change in peak position and intensity upon the application of the ARC. Using this data, in addition to EBIC contrast information, we provide an explanation for the DBL intensity reversal based on the interaction of the detected energy levels with the SiNx:H ARC application. Multiple investigations have suggested that this is a global problem for mc-Si PV cells. Our results have the potential to provide mc-Si PV producers a pathway to increased efficiencies through defect mitigation strategies.

  8. Optical properties of the Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings

    NASA Astrophysics Data System (ADS)

    Marszałek, Konstanty; Winkowski, Paweł; Jaglarz, Janusz

    2014-01-01

    Investigations of bilayer and trilayer Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings are presented in this paper. The oxide films were deposited on a heated quartz glass by e-gun evaporation in a vacuum of 5 × 10-3 [Pa] in the presence of oxygen. Depositions were performed at three different temperatures of the substrates: 100 °C, 200 °C and 300 °C. The coatings were deposited onto optical quartz glass (Corning HPFS). The thickness and deposition rate were controlled with Inficon XTC/2 thickness measuring system. Deposition rate was equal to 0.6 nm/s for Al2O3, 0.6 nm - 0.8 nm/s for HfO2 and 0.6 nm/s for SiO2. Simulations leading to optimization of the thin film thickness and the experimental results of optical measurements, which were carried out during and after the deposition process, have been presented. The optical thickness values, obtained from the measurements performed during the deposition process were as follows: 78 nm/78 nm for Al2O3/SiO2 and 78 nm/156 nm/78 nm for Al2O3/HfO2/SiO2. The results were then checked by ellipsometric technique. Reflectance of the films depended on the substrate temperature during the deposition process. Starting from 240 nm to the beginning of visible region, the average reflectance of the trilayer system was below 1 % and for the bilayer, minima of the reflectance were equal to 1.6 %, 1.15 % and 0.8 % for deposition temperatures of 100 °C, 200 °C and 300 °C, respectively.

  9. New three-layer antireflection/surface passivating coating for high efficiency III-V compound solar cells

    SciTech Connect

    Moulot, J.; Faur, M.; Goradia, C.; Goradia, M.; Faur, M.; Alterovitz, S.; Bailey, S.

    1996-12-31

    By using a chemically grown In(PO{sub 3}){sub 3}-rich oxide layer as the first layer of a 3-layer AR coating, with Al{sub 2}O{sub 3} and MgF{sub 2} as the second and third layers, the authors have addressed the problem of surface passivation and AR coating on InP solar cells. They have designed a 3-layer optimized AR coating for p{sup +}n InP solar cell, which reduces the average reflectance on the surface of cell from about 40% (bare) to less than 2%. At the same time the AR coating significantly improves the J{sub SC} and V{sub OC} by passivating the top surface of the emitter. The authors believe that the significant front surface passivation is to a large extent responsible for their achieving the record high AM0, 25 C, open-circuit voltage of 890.3 mV on a thermally diffused p{sup +}n InP(Cd,S) solar cell. This concept of using a passivating chemically grown oxide as the first layer of a multilayer AR coating can be beneficial to other III-V compound solar cells as well.

  10. Multi-layer coatings

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Abrams, Ze'ev R.; Gonsalves, Peter R.

    2016-06-28

    Disclosed herein are coating materials and methods for applying a top-layer coating that is durable, abrasion resistant, highly transparent, hydrophobic, low-friction, moisture-sealing, anti-soiling, and self-cleaning to an existing conventional high temperature anti-reflective coating. The top coat imparts superior durability performance and new properties to the under-laying conventional high temperature anti-reflective coating without reducing the anti-reflectiveness of the coating. Methods and data for optimizing the relative thickness of the under-layer high temperature anti-reflective coating and the top-layer thickness for optimizing optical performance are also disclosed.

  11. Wet-recess process optimization of a bottom antireflective coating for the via-first dual-damascene scheme

    NASA Astrophysics Data System (ADS)

    Brakensiek, Nickolas L.; Kidd, Brian; Washburn, Carlton A.; Murphy, Earnest

    2004-05-01

    The via-first process is unique by the fact that a material is needed to fill the vias to some arbitrary value, with little or no isolated-dense via bias so that the underlying layer underneath the via is protected from the trench etch step. Secondly, this material may have to coat over the surface of the wafer with some chosen thickness again with minimum or no bias to maximize the trench photolithography process window. Finally, the material must be easily removed from the via after the trench etch with no residue, crowning, or fencing. The ideal via fill material would be able to perform all the above listed parameters, but no perfect solution exists yet. The etchback process that is discussed herein, called the solvent etchback (SOLVE) process bypasses these lengthy modules, will fit within today"s manufacturing processes and will have little impact on throughput of the photobay coating tools. The process utilizes industry standard photoresists solvents such as PGMEA, Ethyl Lactate, PGME and existing solvent prewet dispense nozzles in the BARC coater module. Also, this process only requires one material that can both fill the via and act as a BARC during the trench photo step with a user defined thickness on top the wafer that will minimize light reflections coming from the substrate. The process flow for the SOLVE process is: 1. Coat a wafer with a thick BARC to planarize the wafer and minimize isolated-dense bias. 2. Bake the BARC so that it is partially crosslinked. 3. Apply a solvent to the wafer and etchback the BARC to a thickness that suits the trench photo step. 4. Bake the BARC to fully crosslink the BARC. Process variables that can have an affect on the SOLVE process are the softbake temperature and time to modify the BARC thickness on the wafer. Dispense parameters that will modify the post-etch uniformity of the wafer include the dispense time, dispense spin speed and the IDI M450 dispense pressure. The repeatability of the process can be modified

  12. Comparison of Anti-Reflective Coated and Uncoated Surfaces Figured by Pitch-Polishing and Magneto-Rheological Processes

    SciTech Connect

    Chow, R; Thomas, M D; Bickel, R; Taylor, J R

    2002-11-08

    When completed, the National Ignition Facility (NIF) will provide laser energies in the Mega-joule range. Successful pulse amplification to these extremely high levels requires that all small optics, found earlier in the beamline, have stringent surface and laser fluence requirements. In addition, they must operate reliably for 30 years constituting hundreds of thousands of shots. As part of the first four beamlines, spherical and aspherical lenses were required for the beam relaying telescopes. The magneto-rheological technique allows for faster and more accurate finishing of aspheres. The spherical and aspherical lenses were final figured using both conventional-pitch polishing processes for high quality laser optics and the magneto-rheological finishing process. The purpose of this paper is to compare the surface properties between these two finishing processes. Some lenses were set aside from production for evaluation. The surface roughness in the mid-frequency range was measured and the scatter was studied. Laser damage testing at 1064 nm (3-ns pulse width) was performed on surfaces in both the uncoated and coated condition.

  13. Study of SiO{sub x}N{sub y} as a bottom antireflective coating and its pattern transferring capability

    SciTech Connect

    Peng, X.; Wang, Z.; Dimitrov, D.; Boonstra, T.; Xue, S.

    2007-07-15

    To meet such challenges for the controlling of critical feature dimension at sub-50-100-nm, it has been a general industrial trend to employ shorter wavelength (193 nm, for example) lithography for better resolution and to use bottom antireflective coating (BARC) for a reduced standing wave formation and thus, a better critical dimensional control. Matching the optical constants (n,k) between the BARC, photoresist, and the underlayer to be patterned is critical for the elimination of such standing waves. SiO{sub x}N{sub y} and SiO{sub x}C{sub y} are two attractive inorganic BARC candidates in view of their easily adjustable optical constants by varying the deposition parameters and their etching compatibility with standard semiconductor plasma processes. In this article, SiO{sub x}N{sub y} films were prepared by plasma enhanced chemical vapor deposition approach. These films have been further characterized using x-ray photoelectron spectroscopy for chemical composition depth profile, Fourier transform infrared spectroscopy for local chemical bonding, and ellipsometry for optical constants. It has been demonstrated that the refractive indices of SiO{sub x}N{sub y} can be tuned from 1.6 to 2, while the absorption constants k can be adjusted from 0.1 to 0.9 by changing the process parameters, such as SiH{sub 4} flow rate, NH{sub 3} flow rate, and SiH{sub 4}/N{sub 2}O ratio. To integrate the SiO{sub x}N{sub y} BARC film into the storage device manufacturing, the pattern transferring capability of SiO{sub x}N{sub y} has been discussed. A film stack structure of photoresist/SiO{sub x}N{sub y}/carbon or SiC hard mask/magnetic device layer has been used to evaluate the performance of the SiO{sub x}N{sub y} BARC. SiO{sub x}N{sub y} film was opened via inductively coupled plasma etching with CHF{sub 3}+O{sub 2} chemistry, while carbon and SiC hard masks were opened using He-O{sub 2} and SF{sub 6}-He-O{sub 2} chemistries, respectively. SiF emission line at 388 nm wavelength

  14. Nanotip Carpets as Antireflection Surfaces

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam; Mobasser, Sohrab; Manohara, Harish; Lee, Choonsup

    2008-01-01

    Carpet-like random arrays of metal-coated silicon nanotips have been shown to be effective as antireflection surfaces. Now undergoing development for incorporation into Sun sensors that would provide guidance for robotic exploratory vehicles on Mars, nanotip carpets of this type could also have many uses on Earth as antireflection surfaces in instruments that handle or detect ultraviolet, visible, or infrared light. In the original Sun-sensor application, what is required is an array of 50-micron-diameter apertures on what is otherwise an opaque, minimally reflective surface, as needed to implement a miniature multiple-pinhole camera. The process for fabrication of an antireflection nanotip carpet for this application (see Figure 1) includes, and goes somewhat beyond, the process described in A New Process for Fabricating Random Silicon Nanotips (NPO-40123), NASA Tech Briefs, Vol. 28, No. 1 (November 2004), page 62. In the first step, which is not part of the previously reported process, photolithography is performed to deposit etch masks to define the 50-micron apertures on a silicon substrate. In the second step, which is part of the previously reported process, the non-masked silicon area between the apertures is subjected to reactive ion etching (RIE) under a special combination of conditions that results in the growth of fluorine-based compounds in randomly distributed formations, known in the art as "polymer RIE grass," that have dimensions of the order of microns. The polymer RIE grass formations serve as microscopic etch masks during the next step, in which deep reactive ion etching (DRIE) is performed. What remains after DRIE is the carpet of nano - tips, which are high-aspect-ratio peaks, the tips of which have radii of the order of nanometers. Next, the nanotip array is evaporatively coated with Cr/Au to enhance the absorption of light (more specifically, infrared light in the Sun-sensor application). The photoresist etch masks protecting the apertures

  15. Laser damage by ns and sub-ps pulses on hafnia/silica anti-reflection coatings on fused silica double-sided polished using zirconia or ceria and washed with or without an alumina wash step.

    SciTech Connect

    Bellum, John Curtis; Rambo, Patrick K.; Schwarz, Jens; Kletecka, Damon; Atherton, Briggs W.; Kimmel, Mark W.; Smith, Ian Craig; Smith, Douglas; Hobbs, Zachary

    2010-10-01

    Sandia's Large Optics Coating Operation has extensive results of laser induced damage threshold (LIDT) testing of its anti-reflection (AR) and high reflection coatings on substrates pitch polished using ceria and washed in a process that includes an alumina wash step. The purpose of the alumina wash step is to remove residual polishing compound to minimize its role in laser damage. These LIDT tests are for multi longitudinal mode, ns class pulses at 1064 nm and 532 nm (NIF-MEL protocol) and mode locked, sub-ps class pulses at 1054 nm (Sandia measurements), and show reasonably high and adequate laser damage resistance for coatings in the beam trains of Sandia's Z-Backlighter terawatt and petawatt lasers. An AR coating in addition to coatings of our previous reports confirms this with LIDTs of 33.0 J/cm{sup 2} for 3.5 ns pulses and 1.8 J/cm{sup 2} for 350 fs pulses. In this paper, we investigate both ceria and zirconia in doublesided polishing (common for large flat Z-Backlighter laser optics) as they affect LIDTs of an AR coating on fused silica substrates washed with or without the alumina wash step. For these AR coated, double-sided polished surfaces, ceria polishing in general affords better resistance to laser damage than zirconia polishing and laser damage is less likely with the alumina wash step than without it. This is supported by specific results of laser damage tests with 3.5 ns, multi longitudinal mode, single shot pulses at 1064 nm and 532 nm, with 7.0 ns, single and multi longitudinal mode, single and multi shot pulses at 532 nm, and with 350 fs, mode-locked, single shot pulses at 1054 nm.

  16. Superhydrophobic and omnidirectional antireflective surfaces from nanostructured ormosil colloids.

    PubMed

    Yildirim, Adem; Khudiyev, Tural; Daglar, Bihter; Budunoglu, Hulya; Okyay, Ali K; Bayindir, Mehmet

    2013-02-01

    A large-area superhydrophobic and omnidirectional antireflective nanostructured organically modified silica coating has been designed and prepared. The coating mimics the self-cleaning property of superhydrophobic lotus leaves and omnidirectional broad band antireflectivity of moth compound eyes, simultaneously. Water contact and sliding angles of the coating are around 160° and 10°, respectively. Coating improves the transmittance of the glass substrate around 4%, when coated on a single side of a glass, in visible and near-infrared region at normal incidence angles. At oblique incidence angles (up to 60°) improvement in transmission reaches to around 8%. In addition, coatings are mechanically stable against impact of water droplets from considerable heights. We believe that our inexpensive and durable multifunctional coatings are suitable for stepping out of the laboratory to practical outdoor applications. PMID:23281919

  17. The antireflective potential of dropwise condensation.

    PubMed

    Tow, Emily W

    2014-03-01

    The transmissivity of fogged glass to visible light incident on the dry side is studied with ray tracing to show that condensation can act as an optically thick antireflective coating. A new simulation method is described that uses symmetry relations and analytical expressions for the intersection of rays and surfaces to include all drop-drop and drop-surface interactions between an infinite number of drops. Angle of incidence, droplet contact angle, and surface coverage are varied. The simulation reveals that in the optimal contact angle range, dropwise condensation can decrease the reflectance of glass to below even that of glass coated with a water film. PMID:24690645

  18. Antireflective nanostructured zinc oxide arrays produced by pulsed electrodeposition

    SciTech Connect

    Klochko, N. P. Klepikova, K. S.; Khrypunov, G. S.; Volkova, N. D.; Kopach, V. R.; Lyubov, V. M.; Kirichenko, M. V.; Kopach, A. V.

    2015-02-15

    Conditions for the pulsed electrochemical deposition of nanostructured zinc oxide arrays with a certain morphology, crystal structure, and optical properties from aqueous electrolytes onto substrates of transparent electrically conducting tin dioxide and on single-crystal silicon wafers with built-in homojunctions are studied in order to develop antireflection coatings for solar cells. It is shown that it is possible to obtain single-layer planar antireflection coatings or arrays of nanorods of this material, both having the form of hexagonal prisms and exhibiting the moth-eye effect.

  19. Space qualification of an antireflection coating on the surface of a ruled grating prism: increasing the throughput of the single-object slitless spectroscopy mode of NIRISS onboard JWST

    NASA Astrophysics Data System (ADS)

    Albert, Loïc.; Doyon, René; Kuzmenko, Paul J.; Little, Steve L.; Enzor, Greg S.; Maszkiewicz, Michael

    2014-07-01

    Grating prisms (grism) designed for near-infrared spectroscopy typically make use of high-refractive index materials such as zinc selenide (ZnSe), at the expense of large Fresnel losses ( 18%). Part of the loss can be recovered by using anti-reflection (AR) coatings. The technique is however considered risky when applied on the ruled surface of a grating, especially for a space application at cryogenic temperature. Such a grism, made of ZnSe and machined at Lawrence Livermore National Laboratory (LLNL) is mounted in the Near-Infrared Slitless Spectrograph (NIRISS) onboard the James Webb Space Telescope (JWST). Its Single Object Slitless Spectrograph (SOSS) observing mode uses the ZnSe grism and a cross-dispersing prism to produce R=700 spectra in orders 1 and 2 to cover the 0.6 to 2.5 microns spectral domain. The ZnSe grism is blazed at 1.23 microns, has a density of 54 lines/mm and its triangular grooves have a depth of 700 nm, a base of 18 microns, with facets angled at 1.9 degrees. Here, an AR coating produced by Thin Film Lab (TFL) and deposited on the ruled surface of a ZnSe grism sample was space qualified. Atomic force microscopy (AFM) showed no groove profile change pre/post coating despite the large relative thickness of the AR coating to that of the groove depth ( 35%). Also, the wavefront error map remained almost unchanged at lambda/8 (peak-to-valley at 632 nm) and survived unscathed through a series of three cryogenic cycles to 20 K. Finally, the transmission gain across our operating spectral range was almost as high as that for a unruled surface covered with the same AR coating (10-15%).

  20. A study of the applicability of ZnO thin-films as anti-reflection coating on Cu{sub 2}ZnSnS{sub 4} thin-films solar cell

    SciTech Connect

    Ray, Abhijit; Patel, Malkeshkumar; Tripathi, Brijesh; Kumar, Manoj

    2012-06-25

    Transparent ZnO thin-films are prepared using the RF magnetron sputtering and spray pyrolysis techniques on the glass substrates. Reflectance spectra and thin films heights are measured using spectrophotometer and stylus surface profiler, respectively. Measured optical data is used for investigating the effect of the ZnO prepared by above two processes on the performance of Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films solar cell (TFSC). One dimensional simulation approach is considered using the simulation program, SCAPS. External quantum efficiency and J-V characteristics of CZTS TFSC is simulated on the basis of optical reflectance data of ZnO films with and without ZnO thin-films as antireflection coating (ARC). Study shows that ARC coated CZTS TFSC provides a better fill factor (FF) as compared to other ARC material such as MgF{sub 2}. Sprayed ZnO thin-films as ARC show comparable performance with the sputtered samples.

  1. Templated biomimetic multifunctional coatings

    NASA Astrophysics Data System (ADS)

    Sun, Chih-Hung; Gonzalez, Adriel; Linn, Nicholas C.; Jiang, Peng; Jiang, Bin

    2008-02-01

    We report a bioinspired templating technique for fabricating multifunctional optical coatings that mimic both unique functionalities of antireflective moth eyes and superhydrophobic cicada wings. Subwavelength-structured fluoropolymer nipple arrays are created by a soft-lithography-like process. The utilization of fluoropolymers simultaneously enhances the antireflective performance and the hydrophobicity of the replicated films. The specular reflectivity matches the optical simulation using a thin-film multilayer model. The dependence of the size and the crystalline ordering of the replicated nipples on the resulting antireflective properties have also been investigated by experiment and modeling. These biomimetic materials may find important technological application in self-cleaning antireflection coatings.

  2. BDS Thin Film UV Antireflection Laser Damage Competition

    SciTech Connect

    Stolz, C J

    2010-10-26

    UV antireflection coatings are a challenging coating for high power laser applications as exemplified by the use of uncoated Brewster's windows in laser cavities. In order to understand the current laser resistance of UV AR coatings in the industrial and university sectors, a double blind laser damage competition was performed. The coatings have a maximum reflectance of 0.5% at 355 nm at normal incidence. Damage testing will be performed using the raster scan method with a 7.5 ns pulse length on a single testing facility to facilitate direct comparisons. In addition to the laser resistance results, details of deposition processes and coating materials will also be shared.

  3. Thermal robustness of ion beam sputtered TiO2/SiO2, TiO2/Al2O3 and Al2O3/SiO2 IR anti-reflective coatings on YAG and sapphire substrates

    NASA Astrophysics Data System (ADS)

    Ness, Dale C.; Traggis, Nick; Lyngnes, Ove

    2009-10-01

    As optical coatings are deployed in more extreme environments and applications, mechanical and environmental robustness must be taken into account when designing the film(s). Even minor degradation of the film structure from these outside factors can affect final fluence handling capabilities in operation, and limit the life of the coating. We present the results of a study of maximum thermal handling capabilities of Broad-Band IR Anti-Reflective coatings in the mid-IR (3 to 5 micron) regime. We prepared a family of coated optics utilizing different coating material sets on different substrate materials, and exposed them to a range of increasing temperatures. We examined the damage morphologies under dark field, bright field, and Nomarski microscopy.

  4. Sub-50-nm self-assembled nanotextures for enhanced broadband antireflection in silicon solar cells

    NASA Astrophysics Data System (ADS)

    Rahman, Atikur; Ashraf, Ahsan; Xin, Huolin; Tong, Xiao; Sutter, Peter; Eisaman, Matthew D.; Black, Charles T.

    2015-01-01

    Materials providing broadband light antireflection have applications as highly transparent window coatings, military camouflage, and coatings for efficiently coupling light into solar cells and out of light-emitting diodes. In this work, densely packed silicon nanotextures with feature sizes smaller than 50 nm enhance the broadband antireflection compared with that predicted by their geometry alone. A significant fraction of the nanotexture volume comprises a surface layer whose optical properties differ substantially from those of the bulk, providing the key to improved performance. The nanotexture reflectivity is quantitatively well-modelled after accounting for both its profile and changes in refractive index at the surface. We employ block copolymer self-assembly for precise and tunable nanotexture design in the range of ~10-70 nm across macroscopic solar cell areas. Implementing this efficient antireflection approach in crystalline silicon solar cells significantly betters the performance gain compared with an optimized, planar antireflection coating.

  5. Review of modern techniques to generate antireflective properties on thermoplastic polymers.

    PubMed

    Schulz, Ulrike

    2006-03-01

    Modern optical applications need solutions for providing polymer surfaces with antireflective properties. The problems involved in coating comprise thermal limitations, incompatible mechanical properties of coating and substrate materials, and interaction between polymers and plasma. As an alternative for coating, antireflective properties on polymers can also be obtained by hot embossing or by ion etching of surface structures. My objective is to provide the criteria for choosing suitable deposition or structuring methods based on an understanding of plasma-, radiation-, and ion-induced surface phenomena; material compatibility; mechanical and environmental performance; and cost issues. The potential to produce antireflective interference coatings is documented for plasma-enhanced physical- and chemical-vapor-deposition methods, including modern hybrid techniques, as well as for solgel wet-chemical processes. The review about state-of-the-art coatings focuses on the thermoplastic acrylic, polycarbonate, and cycloolefin polymers. PMID:16539270

  6. Review of modern techniques to generate antireflective properties on thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Schulz, Ulrike

    2006-03-01

    Modern optical applications need solutions for providing polymer surfaces with antireflective properties. The problems involved in coating comprise thermal limitations, incompatible mechanical properties of coating and substrate materials, and interaction between polymers and plasma. As an alternative for coating, antireflective properties on polymers can also be obtained by hot embossing or by ion etching of surface structures. My objective is to provide the criteria for choosing suitable deposition or structuring methods based on an understanding of plasma-, radiation-, and ion-induced surface phenomena; material compatibility; mechanical and environmental performance; and cost issues. The potential to produce antireflective interference coatings is documented for plasma-enhanced physical- and chemical-vapor-deposition methods, including modern hybrid techniques, as well as for solgel wet-chemical processes. The review about state-of-the-art coatings focuses on the thermoplastic acrylic, polycarbonate, and cycloolefin polymers.

  7. Antireflection Pyrex envelopes for parabolic solar collectors

    NASA Astrophysics Data System (ADS)

    McCollister, H. L.; Pettit, R. B.

    1983-11-01

    Antireflective (AR) coatings, applied to the glass envelopes used in parabolic trough solar collectors around the receiver tube in order to reduce thermal losses, can increase solar transmittance by 7 percent. An AR surface has been formed on Pyrex by first heat treating the glass to cause a compositional phase separation, removing a surface layer after heat treatment through the use of a preetching solution, and finally etching in a solution that contains hydrofluorosilic and ammonium bifluoride acids. AR-coated samples with solar transmittance values of more than 0.97, by comparison to an untreated sample value of 0.91, have been obtained for the 560-630 C range of heat treatment temperatures. Optimum values have also been determined for the other processing parameters.

  8. Antireflective surface patterned by rolling mask lithography

    NASA Astrophysics Data System (ADS)

    Seitz, Oliver; Geddes, Joseph B.; Aryal, Mukti; Perez, Joseph; Wassei, Jonathan; McMackin, Ian; Kobrin, Boris

    2014-03-01

    A growing number of commercial products such as displays, solar panels, light emitting diodes (LEDs and OLEDs), automotive and architectural glass are driving demand for glass with high performance surfaces that offer anti-reflective, self-cleaning, and other advanced functions. State-of-the-art coatings do not meet the desired performance characteristics or cannot be applied over large areas in a cost-effective manner. "Rolling Mask Lithography" (RML™) enables highresolution lithographic nano-patterning over large-areas at low-cost and high-throughput. RML is a photolithographic process performed using ultraviolet (UV) illumination transmitted through a soft cylindrical mask as it rolls across a substrate. Subsequent transfer of photoresist patterns into the substrate is achieved using an etching process, which creates a nanostructured surface. The current generation exposure tool is capable of patterning one-meter long substrates with a width of 300 mm. High-throughput and low-cost are achieved using continuous exposure of the resist by the cylindrical photomask. Here, we report on significant improvements in the application of RML™ to fabricate anti-reflective surfaces. Briefly, an optical surface can be made antireflective by "texturing" it with a nano-scale pattern to reduce the discontinuity in the index of refraction between the air and the bulk optical material. An array of cones, similar to the structure of a moth's eye, performs this way. Substrates are patterned using RML™ and etched to produce an array of cones with an aspect ratio of 3:1, which decreases the reflectivity below 0.1%.

  9. Fluorine-containing composition for forming anti-reflection film on resist surface and pattern formation method

    DOEpatents

    Nishi, Mineo; Makishima, Hideo

    1996-01-01

    A composition for forming anti-reflection film on resist surface which comprises an aqueous solution of a water soluble fluorine compound, and a pattern formation method which comprises the steps of coating a photoresist composition on a substrate; coating the above-mentioned composition for forming anti-reflection film; exposing the coated film to form a specific pattern; and developing the photoresist, are provided. Since the composition for forming anti-reflection film can be coated on the photoresist in the form of an aqueous solution, not only the anti-reflection film can be formed easily, but also, the film can be removed easily by rinsing with water or alkali development. Therefore, by the pattern formation method according to the present invention, it is possible to form a pattern easily with a high dimensional accuracy.

  10. TiO2/SiO2 multilayer as an antireflective and protective coating deposited by microwave assisted magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mazur, M.; Wojcieszak, D.; Domaradzki, J.; Kaczmarek, D.; Song, S.; Placido, F.

    2013-06-01

    In this paper designing, preparation and characterization of multifunctional coatings based on TiO2/SiO2 has been described. TiO2 was used as a high index material, whereas SiO2 was used as a low index material. Multilayers were deposited on microscope slide substrates by microwave assisted reactive magnetron sputtering process. Multilayer design was optimized for residual reflection of about 3% in visible spectrum (450-800 nm). As a top layer, TiO2 with a fixed thickness of 10 nm as a protective film was deposited. Based on transmittance and reflectance spectra, refractive indexes of TiO2 and SiO2 single layers were calculated. Ultra high vacuum atomic force microscope was used to characterize the surface properties of TiO2/SiO2 multilayer. Surface morphology revealed densely packed structure with grains of about 30 nm in size. Prepared samples were also investigated by nanoindentation to evaluate their protective performance against external hazards. Therefore, the hardness of the thin films was measured and it was equal to 9.34 GPa. Additionally, contact angle of prepared coatings has been measured to assess the wetting properties of the multilayer surface.

  11. Effects of CO 2 laser conditioning of the antireflection Y 2O 3/SiO 2 coatings at 351 nm

    NASA Astrophysics Data System (ADS)

    Wei, Chaoyang; He, Hongbo; Shao, Jianda; Wang, Tao; Zhang, Dongping; Fan, Zhengxiu

    2005-08-01

    Y 2O 3/SiO 2 coatings were deposited on fused silica by electron beam evaporation. A continuous wave CO 2 laser was used to condition parts of the prepared samples at different scanning speeds in the air. LAMBDA 900 spectrometer was used to investigate the changes of the transmittance and residual reflection spectrum. A Nomarski microscope under dark field was used to examine the changes of the micro defect density. The changes of the surface roughness and the microstructure of the film before and after conditioning were investigated by AFM and X-ray diffraction, respectively. We found that laser-induced damage threshold (LIDT) of the films conditioning at 30 mm/s scanning speed was increased by more than a factor of 3 over the thresholds of the as-deposited films. The conditioning effect was correlated with an irradiation-induced decrease of the defect density and absorption of the films.

  12. Utilizing contrast enhancement material as a topside antireflective coating (TARC) for maximizing an i-line 0.35-um process window

    NASA Astrophysics Data System (ADS)

    Moynihan, Matthew L.; Markowski, Mark S.

    1995-06-01

    As critical dimensions become smaller, a greater demand is being placed on existing i-line lithographic capability to support 0.35 micrometers technology. One method that is gaining wider acceptance is the use of a top side anti reflective coating (TARC). The effect of the TARC is to reduce the interference effects occurring in the film stack so that critical dimension (CD) variation as a result of topography is minimized. Unfortunately, the TARC provides no improvement with other lithographic responses that define the process window of a resist. Another approach is to use a contrast enhancement material (CEM). It is well known that a CEM can improve the depth of focus and resolution of a given resist system, and it is suspected that it may also possess some of the interference reduction properties of conventional TARCs. The purpose of this work is to investigate how effective the CEM acts as a TARC, and to determine any additional lithographic improvements which will increase the overall 0.35 micrometers process window. Process optimization of the CEM and TARC revealed that similar processing schemes could be used for both materials, but that it was necessary to remove the CEM (w/ a water rinse) prior to post exposure bake (PEB). The bulk photospeed swing ratio of the SPR3000 alone, was compared to SPR3000/Aquatar and SPR3000/CEM. Results showed that the Aquatar reduced the Eo swing ratio by 75%, while the CEM reduced the Eo swing ratio by about 55%. Similar improvements were seen with 0.35 micrometers CD swing ratio data. Exposure latitude and focus latitude (0.35 micrometers lines/spaces) data was generated using the same resist/enhancement schemes mentioned above at thicknesses corresponding to an Emax and Emin. Results of the lithography at each thickness were overlaid to determine the process window. Results showed the Aquatar and CEM processes to provide improved 0.35 micrometers windows, and that using a contrast enhancement material as a TARC is another

  13. Tunable Antireflection Layers for Planar Bolometer Arrays

    NASA Technical Reports Server (NTRS)

    Brown, Ari-David; Chuss, David; Woolack, Edward; Chervenak, James; Henry, Ross; Wray, James

    2007-01-01

    It remains a challenge to obtain high-efficiency coupling of far-infrared through millimeter radiation to large-format detector arrays. The conventional approach of increasing detector coupling is to use reflective backshorts. However, this approach often results in excessive systematic errors resulting from reflections off the backshort edge. An alternate approach to both increasing quantum efficiency and reducing systematics associated with stray light is to place an antireflective coating near the front surface of the array. When incorporated with a resistive layer and placed behind the detector focal plane, the AR coating can serve to prevent optical ghosting by capturing radiation transmitted through the detector. By etching a hexagonal pattern in silicon, in which the sizes of the hexes are smaller than the wavelength of incident radiation, it is possible to fabricate a material that has a controllable dielectric constant, thereby allowing for simple tunable optical device fabrication. To this end, we have fabricated and tested tunable silicon "honeycomb" AR layers and AR/resistive layer devices. These devices were fabricated entirely out of silicon in order to eliminate problems associated with differential contraction upon detector cooling.

  14. Thermal radiative properties: Coatings.

    NASA Technical Reports Server (NTRS)

    Touloukian, Y. S.; Dewitt, D. P.; Hernicz, R. S.

    1972-01-01

    This volume consists, for the most part, of a presentation of numerical data compiled over the years in a most comprehensive manner on coatings for all applications, in particular, thermal control. After a moderately detailed discussion of the theoretical nature of the thermal radiative properties of coatings, together with an overview of predictive procedures and recognized experimental techniques, extensive numerical data on the thermal radiative properties of pigmented, contact, and conversion coatings are presented. These data cover metallic and nonmetallic pigmented coatings, enamels, metallic and nonmetallic contact coatings, antireflection coatings, resin coatings, metallic black coatings, and anodized and oxidized conversion coatings.

  15. Development of new maskless manufacturing method for anti-reflection structure and application to large-area lens with curved surface

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuya; Takaoka, Toshimitsu; Fukui, Hidetoshi; Haruta, Yasuyuki; Yamashita, Tomoya; Kitagawa, Seiichiro

    2016-03-01

    In general, thin-film coating process is widely applied on optical lens surface as anti-reflection function. In normal production process, at first lens is manufactured by molding, then anti-reflection is added by thin-film coating. In recent years, instead of thin-film coating, sub-wavelength structures adding on surface of molding die are widely studied and development to keep anti-reflection performance. As merits, applying sub-wavelength structure, coating process becomes unnecessary and it is possible to reduce man-hour costs. In addition to cost merit, these are some technical advantages on this study. Adhesion of coating depends on material of plastic, and it is impossible to apply anti-reflection function on arbitrary surface. Sub-wavelength structure can solve both problems. Manufacturing method of anti-reflection structure can be divided into two types mainly. One method is with the resist patterning, and the other is mask-less method that does not require patterning. What we have developed is new mask-less method which is no need for resist patterning and possible to impart an anti-reflection structure to large area and curved lens surface, and can be expected to apply to various market segments. We report developed technique and characteristics of production lens.

  16. Broadband Infrared Antireflection Structured Silicon Surfaces

    NASA Technical Reports Server (NTRS)

    Stewart, Kenneth; Fettig, Rainer; Allen, Christine; Larocque, Jennifer

    1999-01-01

    Silicon and germanium are materials often used for infrared (IR) windows and optical elements. However they have a very high index of refraction, in the order of three to four, which causes large reflection losses on each surface. These losses are especially high under large angles of incidence which are often desirable if signals are faint and fast optics are to be used. Solid antireflection coatings are either not available because materials with appropriate index of refraction do not exist, or their use is limited to a small wavelength range and small angles of incidence. We will present the status of our work to calculate, create, and test the performance of graded structures in Si to reduce its surface reflection. The structures are expected to work over the very broad wavelength range of 10 micron to 1000 micron and a wide range of angle of incidence. We.have identified several high aspect ratio MEMS process techniques to create the structures and have done 3D electromagnetic modeling, which predicts significant effects. Measurements on different samples have validated our modeling.

  17. Broadband Infrared Antireflection Structured Silicon Surfaces

    NASA Technical Reports Server (NTRS)

    Stewart, Kenneth; Fettig, Rainer; Allen, Christine; Larocque, Jennifer

    1999-01-01

    Silicon and germanium are materials often used for IR windows and optical elements. However they have a very high index of refraction, in the order of three to four, which causes large reflection losses on each surface. These losses are especially high under large angles of incidence which are often desirable if signals are faint and fast optics are to be used. Solid antireflection coatings are either not available because materials with appropriate index of refraction do not exist, or their use is limited to a small wavelength range and small angles of incidence. We will present the status of our work to calculate, create, and test the performance of graded structures in Si to reduce its surface reflection. The structures are expected to work over the very broad wavelength range of 10 to 1000 micrometers and a wide range of angle of incidence. We have identified several high aspect ratio MEMS process techniques to Create the structures and have done 3D electromagnetic modeling, which predicts significant effects. Measurements on different samples have validated our modeling.

  18. Broadband Infrared Antireflection Structured Silicon Surfaces

    NASA Technical Reports Server (NTRS)

    Stewart, Kenneth; Fettig, Rainer; Allen, Christine; Fettig, Rainer; Larocque, Jennifer

    1998-01-01

    Silicon and germanium are materials often used for IR windows and optical elements. However they have a very high index of refraction, in the order of three to four, which causes large reflection losses on each surface. These losses are especially high under large angles of incidence which are often desirable if signals are faint and fast optics are to be used. Solid antireflection coatings are either not available because materials with appropriate index of refraction do not exist, or their use is limited to a small wavelength range and small angles of incidence. We will present the status of our work to calculate, create, and test the performance of graded structures in Si to reduce its surface reflection. The structures are expected to work over the very broad wavelength range of 10 microns to 1000 microns and a wide range of angle of incidence. We have identified several high aspect ratio MEMS process techniques to create the structures and have done 3D electromagnetic modeling, which predicts significant effects. Measurements on different samples have validated our modeling.

  19. Nanostructured Antireflective and Thermoisolative Cicada Wings.

    PubMed

    Morikawa, Junko; Ryu, Meguya; Seniutinas, Gediminas; Balčytis, Armandas; Maximova, Ksenia; Wang, Xuewen; Zamengo, Massimiliano; Ivanova, Elena P; Juodkazis, Saulius

    2016-05-10

    Inter-related mechanical, thermal, and optical macroscopic properties of biomaterials are defined at the nanoscale by their constituent structures and patterns, which underpin complex functions of an entire bio-object. Here, the temperature diffusivity of a cicada (Cyclochila australasiae) wing with nanotextured surfaces was measured using two complementary techniques: a direct contact method and IR imaging. The 4-6-μm-thick wing section was shown to have a thermal diffusivity of α⊥ = (0.71 ± 0.15) × 10(-7) m(2)/s, as measured by the contact temperature wave method along the thickness of the wing; it corresponds to the inherent thermal property of the cuticle. The in-plane thermal diffusivity value of the wing was determined by IR imaging and was considerably larger at α∥ = (3.6 ± 0.2) × 10(-7) m(2)/s as a result of heat transport via air. Optical properties of wings covered with nanospikes were numerically simulated using an accurate 3D model of the wing pattern and showed that light is concentrated between spikes where intensity is enhanced by up to 3- to 4-fold. The closely packed pattern of nanospikes reduces the reflectivity of the wing throughout the visible light spectrum and over a wide range of incident angles, hence acting as an antireflection coating. PMID:27101865

  20. Antireflection-structured surfaces for mid-infrared entrance windows

    NASA Astrophysics Data System (ADS)

    Dubreuil, Didier; Harvey, Erol C.; Pigot, Claude; Rizvi, Nadeem H.

    1998-08-01

    SubWavelength Structured Surfaces (SWS), by synthesizing effective index of refraction, offer an attractive way to mimic antireflective coating effects. It is of particular interest for some IR materials of high index of refraction such as CdTe or KRS-5. These material are often used for entrance window in cryogenic IR instrument in the 20 microns band. For these materials, multilayer antireflective coatings provide limited performances in transmission, while expected performances of SWS can be very high even for a wavelength range covering both the N and Q atmospheric windows, from 7 microns to 28 microns. The SWS simulates a gradient index layer. Its main parameters are its pitch and its depth. The pitches required depend on the IR material index. For CdTe and KRS5, they are around 3 microns to work in N-band and Q-band and around 6 microns to work only on Q- band, and the depth required is around 10 microns to work till 28 microns. We have tried a new approach to realize these structures by using excimer laser ablation technique. We describe the used technique and our results for different materials such as CdTe, KRS5, CsBr and CsI. Antireflection structured surfaces on CdTe could offer an increase in transmission better than 25 percent at 24 microns. We measured a transmission efficiency of near 96 percent between 23 micrometers and 35 micrometers on KRS-5, and more than 95 percent between 18.5 micrometers and 35.5 micrometers on CsI.

  1. Development of broadband antireflection of high-index substrate using SiNx/SiO2

    NASA Astrophysics Data System (ADS)

    Lim, Kim Peng; Ng, Doris K. T.; Wang, Qian

    2016-03-01

    Broadband antireflection coatings are commonly required in many silicon or III-V compound semiconductor based optoelectronic devices such as solar cells, photodetectors, and image sensors so as to enhance light conversion efficiency. Conventional approach using a single-layer antireflection coating is simple and commonly used in industry but it has a limited working bandwidth. To achieve broadband or even omni-directional characteristics, structures using thick graded refractive index (GRIN) multilayers or nanostructured surfaces which have equivalent graded refractive index profile have been proposed and demonstrated. In this paper, we will show our development of broadband antireflection for high index substrate using SiNx/SiO2 via inductively coupled plasma chemical vapour deposition (ICPCVD). Global optimization of thin-film broadband antireflection coating using adaptive simulated annealing is presented. Unlike the conventional optical coating design which uses the refractive index of available materials, the optimization approach used here decides the optimal values of the refractive index as well as the thickness of each layer. The first thin-film material optimization is carried out on the ICP-CVD machine operating at low temperature of 250°C by tuning the SiH4/N2 gas ratio. The demonstrated double layer antireflection thin film reduces the average reflectance of Si surface from ~32% to ~3.17% at normal incidence for wavelength range from 400 to 1100 nm. This optical thin-film design and material development can be extended to optical wavelength filters and integrated micro-GRIN devices.

  2. Antireflection pyrex envelopes for parabolic solar collectors

    SciTech Connect

    McCollister, H.L.; Pettit, R.B.

    1983-01-01

    Parabolic trough solar collectors utilize glass envelopes around the receiver tube in order to reduce thermal losses. Antireflective (AR) coatings applied to the envelope can potentially increase the solar transmittance by 0.07. An excellent AR surface can be formed on Pyrex (Corning Code 7740 glass) by first heat treating the glass to cause a compositional phase separation. After heat treating, a surface layer is removed using a pre-etch solution of aqueous ammonium bifluoride. Finally the AR layer is formed by etching in a solution containing hydrofluorosilic and ammonium bifluoride acid. Processing parameters studied included the phase separation temperature and heat treatment time, the pre-etch time, and the etching bath temperature and time. AR-coated samples with solar transmittance values >0.97, as compared to a value of 0.91 in untreated samples, were obtained for a range of heat treatment temperatures from 560 to 630/sup 0/C. The phase separation time and temperature interact so that at 630/sup 0/C short times are required (3 hours) while at 560/sup 0/C longer times are necessary (24 hours). Optimum values for the other processing parameters are 12 to 18 minutes in the pre-etching bath, and 5 to 10 minutes in the film forming bath when maintained between 35 and 45/sup 0/C. Application of this process to full scale 3 m long x 6 cm diameter Pyrex envelopes was successful in producing solar transmittance values greater than or equal to 0.97.

  3. Antireflection Pyrex envelopes for parabolic solar collectors

    SciTech Connect

    McCollister, H.L.; Pettit, R.B.

    1983-11-01

    Parabolic trough solar collectors utilize glass envelopes around the receiver tube in order to reduce thermal losses. Antireflective (AR) coatings applied to the envelope can potentially increase the solar transmittance by 7 percent. An excellent AR surface can be formed on Pyrex (Corning Code 7740 glass) by first heat treating the glass to cause a compositional phase separation. After heat treating, a surface layer is removed using a pre-etch solution of aqueous ammonium bifluoride. Finally, the AR layer is formed by etching in a solution containing hydrofluorosilic and ammonium bifluoride acid. Processing parameters studied included the phase separation temperature and heat treatment time, the pre-etch time, and the etching bath temperature and time. AR-coated samples with solar transmittance values > 0.97, as compared to a value of 0.91 in untreated samples, were obtained for a range of heat treatment temperatures from 560-630/sup 0/C. The phase separation time and temperature interact so that at 630/sup 0/C short times are required (3 hrs) while at 560/sup 0/C longer times are necessary (24 hrs). Optimum values for the other processing parameters are 12-18 min in the pre-etching bath, and 5-10 min in the film forming bath when maintained between 35-45/sup 0/C. Application of this process to full scale 3-m-long X 6-cm dia Pyrex envelopes was successful in producing solar transmittance values greater than or equal to 0.97.

  4. Waveguide-based antireflection structure

    NASA Astrophysics Data System (ADS)

    Zhu, Zhongshu; Li, Xun

    2016-04-01

    A waveguide-based antireflection structure is proposed. The device consists of two polarization rotators (PRs), two polarization-distinguished 90-deg phase delay units (PDUs), and a polarization beam combiner (PBC). The PR and PDU, providing the same function as a quarter wave plate in free-space optics, convert a linearly polarized light into a circularly polarized light. Upon reflection from an isotropic homogenous interface, the returned light is converted back into a linearly polarized light in its perpendicular direction. Through the PBC placed at the input port, the returned light is then redirected into a different port for further use or discard. Our three-dimensional mode-matching method-based simulation shows that, on the silicon-on-insulator waveguide platform, the total device length can be made as short as 10.5 μm.

  5. Antireflection/Passivation Step For Silicon Cell

    NASA Technical Reports Server (NTRS)

    Crotty, Gerald T.; Kachare, Akaram H.; Daud, Taher

    1988-01-01

    New process excludes usual silicon oxide passivation. Changes in principal electrical parameters during two kinds of processing suggest antireflection treatment almost as effective as oxide treatment in passivating cells. Does so without disadvantages of SiOx passivation.

  6. Enhancement in broadband and quasi-omnidirectional antireflection of nanopillar arrays by ion milling.

    PubMed

    Huang, Zhifeng; Hawkeye, Matthew M; Brett, Michael J

    2012-07-11

    A new technique is developed to fabricate biomimetic antireflection coatings (ARCs). This technique combines a bottom-up fabrication approach (glancing angle deposition, or GLAD) with a top-down engineering process (ion milling). The GLAD technique is first utilized to produce nanopillar arrays (NPAs) with broadened structures, which are subsequently transformed into biomimetic tapered geometries by means of post-deposition ion milling. This structure transformation, due to milling-induced mass redistribution, remarkably decreases reflection over a wide wavelength range (300-1700 nm) and field of view (angle of incidence < 60° with respect to the substrate normal). The milling-induced antireflection enhancement has been demonstrated in the NPAs made of Si, SiO(x) and TiO(2), illustrating that this integrated technique is readily adapted to a wide variety of materials. Good agreement between simulation and experiment indicates that the enhanced antireflection performance is ascribed to a smoother refractive index transition from the substrate to the air, which improves the impedance match and reduces reflection losses. Additionally, ion bombardment tends to alter the stoichiometry and diminish the crystallographic structure of the NPA materials. The broadband and quasi-omnidirectional antireflection observed establishes the strong competitiveness of this technique with the methods previously reported. PMID:22705498

  7. Design and fabrication of infrared antireflecting bi-periodic micro-structured surfaces

    NASA Astrophysics Data System (ADS)

    Bouffaron, R.; Escoubas, L.; Simon, J. J.; Torchio, Ph.; Flory, F.; Berginc, G.; Masclet, Ph.; Perret, C.; Schiavone, P.

    2008-04-01

    Broadband antireflection properties of material surfaces are of primary interest for a wide variety of applications: to enhance the efficiency of photovoltaic cells, to increase the sensitivity of photodetectors, to improve the performance of light emitting diodes, etc... In the past, broadband antireflection multilayer coatings were widely used and recently very low refractive index materials in thin film form have been fabricated by several groups. The research work presented in this paper aims at modeling and fabricating bi-periodic micro-structured silicon surfaces exhibiting broadband antireflection properties in the infrared range. These structures of pyramidal shape, which typical dimensions are smaller than the wavelength, are not in the Effective Medium Theory (EMT) validity domain. The optimization of the optical properties of such patterned surfaces needs a fully Finite Difference Time Domain (FDTD) rigorous description of light propagation phenomena. The influence of various opto-geometrical parameters such as period, depth, shape of the pattern is examined. The antireflective properties of such bi-periodic patterned surfaces is then discussed using the photonic crystal theory and photonic band diagrams description. The structure is considered as a two dimensional periodic structure with a nonuniform third dimension. Correlations between the density of Bloch modes, flatness of dispersion curves and the surface reflectance are presented. The last part of this paper is devoted to the presentation of the fabrication and the characterization of the structures. Low cost and large surface processing techniques are proposed using wet anisotropic etching through a silica mask obtained by photolithography or nanoimprinting.

  8. Simulation and Implementation of Moth-eye Structures as a Broadband Anti-Reflective Layer

    NASA Astrophysics Data System (ADS)

    Deshpande, Ketan S.

    Conventional single layer thin anti-reflective coatings (ARCs) are only suitable for narrowband applications. A multilayer film stack is often employed for broadband applications. A coating of multiple layers with alternating low and high refractive index materials increases the overall cost of the system. This makes multilayer ARCs unsuitable for low-cost broadband applications. Since the discovery of moth-eye corneal nipple patterns and their potential applicability in the field of broadband ARCs, many studies have been carried out to fabricate these bio-inspired nanostructures with available manufacturing processes. Plasma etching processes used in microelectronic manufacturing are applied for creating these nanostructures at the Rochester Institute of Technology's Semiconductor & Microsystems Fabrication Laboratory (SMFL). Atomic Force Microscope (AFM) scanned surfaces of the nanostructure layer are simulated and characterized for their optical properties using a Finite-Difference Time Domain (FDTD) simulator from Lumerical Solutions, Inc. known as FDTD Solutions. Simulation results show that the layer is anti-reflective over 50 to 350 nm broadband of wavelengths at 0° angle of incidence. These simulation results were supported by ellipsometer reflection measurements off the actual samples at multiple angles of light incidence, which show a 10% to 15% decrease in reflection for 240 to 400 nm wavelengths. Further improvements in the optical efficiency of these structures can be achieved through simulation-fabrication-characterization cycles performed for this project. The optimized nanostructures can then serve the purpose of low-cost anti-reflective coatings for solar cells and similar applications.

  9. Coatings Boost Solar-Cell Outputs

    NASA Technical Reports Server (NTRS)

    Rohatgi, Ajeet; Campbell, Robert B.; O'Keefe, T. W.; Rai-Choudbury, Posenjit; Hoffman, Richard A.

    1988-01-01

    Efficiencies increased by more-complete utilization of incident light. Electrical outputs of thin solar photovoltaic cells made of dendritic-web silicon increased by combination of front-surface, antireflective coatings and back-surface, reflective coatings. Improvements achieved recently through theoretical and experimental studies of ways to optimize coatings for particular wavelengths of incident light, cell thicknesses, and cell materials.

  10. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  11. Broadband Antireflection and Light Extraction Enhancement in Fluorescent SiC with Nanodome Structures

    PubMed Central

    Ou, Yiyu; Zhu, Xiaolong; Jokubavicius, Valdas; Yakimova, Rositza; Mortensen, N. Asger; Syväjärvi, Mikael; Xiao, Sanshui; Ou, Haiyan

    2014-01-01

    We demonstrate a time-efficient and low-cost approach to fabricate Si3N4 coated nanodome structures in fluorescent SiC. Nanosphere lithography is used as the nanopatterning method and SiC nanodome structures with Si3N4 coating are formed via dry etching and thin film deposition process. By using this method, a significant broadband surface antireflection and a considerable omnidirectional luminescence enhancement are obtained. The experimental observations are then supported by numerical simulations. It is believed that our fabrication method will be well suitable for large-scale production in the future. PMID:24722521

  12. Zinc Oxide LB Films with Improved Antireflective, Photoactive and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Naszályi Nagy, Lívia; Ábrahám, Nóra; Kovács, Attila L.; van der Lee, Arie; Rouessac, Vincent; Cot, Didier; Ayral, André; Hórvölgyi, Z.

    Multifunctional Langmuir-Blodgett films were prepared using sol-gel derived ZnO and silica nanoparticles synthesized by the procedure of Seelig et al. [1] and Stöber et al. [2], respectively. High inherent porosity was observed for ZnO particles (30-40%) by pycnometry, scanning angle reflectometry, N2 adsorption-desorption and ellipsometric porosimetry methods. Water contact angle of ZnO nanoparticles was determined from the non-dissipative part of the obtained surface pressure-surface area isotherms, and by scanning angle reflectometry measurements in a Wilhelmy film balance. Antireflective and photocatalytically active coatings of ZnO particles were deposited on glass, conductive glass and silicon substrates. The antireflectivity of ZnO LB films was improved by the integration of silica nanoparticles in the LB film. The photocatalytic activity and the mechanical stability of the samples were enhanced by means of surface modification with 3-methacryloxypropyl(trimethoxy)silane.

  13. Antireflective silica thin films with super water repellence via a solgel process.

    PubMed

    Xu, Yao; Fan, Wen Hao; Li, Zhi Hong; Wu, Dong; Sun, Yu Han

    2003-01-01

    A solgel process was developed, through which silica films possessing both high antireflection and super water repellence were obtained. In this process, methyl-modified SiO2 sols synthesized by colloidal suspension of SiO2 particles and hexamethyldisilazane (HMDS) were used to deposit spinning-coating films on optical glass substrates. On the resultant films the contact angle for water increased with the increasing amount of HMDS in the reaction mixture. The biggest contact angle was 165 degrees, and the lowest reflectivity on one-sided film reached 0.03%. The antireflections were high all the while. One advantage of this process is that neither a roughened surface nor fluoroalkyltrialkoxylsilane (FAS) is needed to obtained super water repellence. PMID:12518829

  14. Enhancing transmission efficiency of bending waveguide based on graded sonic crystals using antireflection structures

    NASA Astrophysics Data System (ADS)

    Wu, Liang-Yu; Chen, Lien-Wen

    2012-06-01

    The conventional antireflection coating (ARC) structure for sonic crystal devices is to place the cylinders at the interface between a sonic crystal device and a background medium. The radius of ARC cylinders and the distance between the ARC and the sonic crystal device are adjusted to obtain an optimal antireflection effect. We propose that ARC structures are directly designed by using the conventional ARC theory instead of scanning the geometric and spatial parameters of the conventional ARC structures. According to the concept of the effective refractive index of sonic crystals, the exact ARC structures can be implemented by sonic crystals. The transmission efficiency of a bending waveguide designed by graded sonic crystals can be enhanced by introducing the ARC structures based on sonic crystals. The performances of different ARC structure designs are compared and discussed.

  15. Durable superhydrophobic and antireflective surfaces by trimethylsilanized silica nanoparticles-based sol-gel processing.

    PubMed

    Manca, Michele; Cannavale, Alessandro; De Marco, Luisa; Aricò, Antonino S; Cingolani, Roberto; Gigli, Giuseppe

    2009-06-01

    We present a robust and cost-effective coating method to fabricate long-term durable superhydrophobic andsimultaneouslyantireflective surfaces by a double-layer coating comprising trimethylsiloxane (TMS) surface-functionalized silica nanoparticles partially embedded into an organosilica binder matrix produced through a sol-gel process. A dense and homogeneous organosilica gel layer was first coated onto a glass substrate, and then, a trimethylsilanized nanospheres-based superhydrophobic layer was deposited onto it. After thermal curing, the two layers turned into a monolithic film, and the hydrophobic nanoparticles were permanently fixed to the glass substrate. Such treated surfaces showed a tremendous water repellency (contact angle = 168 degrees ) and stable self-cleaning effect during 2000 h of outdoor exposure. Besides this, nanotextured topology generated by the self-assembled nanoparticles-based top layer produced a fair antireflection effect consisting of more than a 3% increase in optical transmittance. PMID:19466786

  16. Control of polarization effects by internal antireflection.

    PubMed

    Knittl, Z

    1981-01-01

    Mouchart's theory of the buffer layer is reformulated in terms of internal antireflection and extended to general dielectric/metallic media. The all-dielectric case is then studied in oblique incidence as a means of depolarizing partial reflectors. Several procedures are indicated for the construction of buffering stacks which, when coupled with germinal stacks, balance out their p and s reflections at the given level. Examples of depolarized half-mirrors are presented. A novel version of the Argand diagram for thin films in oblique incidence is introduced during the analysis. PMID:20309073

  17. Precise replication of antireflective nanostructures from biotemplates

    NASA Astrophysics Data System (ADS)

    Gao, Hongjun; Liu, Zhongfan; Zhang, Jin; Zhang, Guoming; Xie, Guoyong

    2007-03-01

    The authors report herein a new type of nanonipple structures on the cicada's eye and the direct structural replication of the complex micro- and nanostructures for potential functional emulation. A two-step direct molding process is developed to replicate these natural micro- and nanostructures using epoxy resin with high fidelity, which demonstrates a general way of fabricating functional nanostructures by direct replication of natural biotemplates via a suitable physicochemical process. Measurements of spectral reflectance showed that this kind of replicated nanostructure has remarkable antireflective property, suggestive of its potential applications to optical devices.

  18. Design of optical coatings

    NASA Astrophysics Data System (ADS)

    Gunkel, Claus W.

    1990-08-01

    A highly sophisticated antireflection coating and a cut-on-filter - designed by the Leitz program "RDP" - will be pointed out. The program runs on a VAX 8530 and allows to calculate reflectance, transmittance and phase of randomly polarized light which interacts with marginal surfaces. The number of layers is not limited. Some or even all layers are allowed to be anistropic. Up to four layers may be inhomogeneous both in refractive indices and absorption constants. At a time two thicknesses, two refractive indices and absorption constants as well as the angles of incidence may be varied independently in each run. The calculated values will be compared with the results of measurements. The antireflection coating is evaporated in a Balzers high vacuum evaporation plant, controlled by the process unit BPU 420, whereas the cut-on filter is evaporated in a Leybold box coater with Leycom III and two electron-beam guns.

  19. Vacuum deposited optical coatings experiment

    NASA Technical Reports Server (NTRS)

    Charlier, Jean

    1992-01-01

    The 138-4 Frecopa experiment consisted of 20 sorts of optical components and coatings subjected to space exposure. They covered a large range of use from the UV to IR spectrum: filters, mirrors, dichroics, beam splitters, and antireflection coatings made of several different materials as layers and substrates. By comparing pre- and post-flight spectral performances, it was possible to put into evidence the alterations due to space exposure.

  20. A simple and fast fabrication of a both self-cleanable and deep-UV antireflective quartz nanostructured surface

    PubMed Central

    2012-01-01

    Both self-cleanability and antireflectivity were achieved on quartz surfaces by forming heptadecafluoro-1,1,2,2-tetrahydrodecyltrichlorosilane self-assembled monolayer after fabrication of nanostructures with a mask-free method. By exposing polymethylmethacrylate spin-coated quartz plates to O2 reactive ion etching (RIE) and CF4 RIE successively, three well-defined types of nanopillar arrays were generated: A2, A8, and A11 patterns with average pillar widths of 33 ± 4 nm, 55 ± 5 nm, and 73 ± 14 nm, respectively, were formed. All the fabrication processes including the final cleaning can be finished within 4 h. All nanostructured quartz surfaces exhibited contact angles higher than 155° with minimal water droplet adhesiveness and enhanced transparency (due to antireflectivity) over a broad spectral range from 350 to 900 nm. Furthermore, A2 pattern showed an enhanced antireflective effect that extends to the deep-UV range near 190 nm, which is a drawback region in conventional thin-film-coating approaches as a result of thermal damage. Because, by changing the conditions of successive RIE, the geometrical configurations of nanostructure arrays can be easily modified to meet specific needs, the newly developed fabrication method is expected to be applied in various optic and opto-electrical areas. PACS codes: 06.60.Ei; 81.65.Cf; 81.40.Vw. PMID:22853428

  1. Antireflection coatings based on fluoride formulations for organic solar cells

    NASA Astrophysics Data System (ADS)

    Suleimanov, S. Kh.; Berger, P.; Dyskin, V. G.; Dzhanklych, M. U.; Bugakov, A. G.; Dudko, O. A.; Kulagina, N. A.; Kim, M.

    2016-04-01

    An alloy of a mixture of fluorides MgF2 and AlF3 with CaF2 has been obtained in a 3-kW solar furnace. It was supposed that a minor CaF2 additive compensates for the tensile stresses appearing in thin MgF2 and AlF3 films, with their mechanical properties being thereby improved. The results of X-ray phase analysis demonstrated that both components of the mixture are present in the alloy, while the complex oxide CaAl4O7, the formation of which is attributed to the melting in air, is only identified in AlF3: CaF2 = 95: 5 (wt %). The increase in the transmittance of glass and polyethylene terephthalate upon deposition onto their surface of a thin film of the material synthesized in the study is due to the optical properties of AlF3 and MgF2.

  2. Laser processing of solar cells with anti-reflective coating

    DOEpatents

    Harley, Gabriel; Smith, David D.; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John

    2016-02-16

    Contact holes of solar cells are formed by laser ablation to accommodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thicknesses.

  3. High efficiency infrared antireflection coatings (ARCs) for space optics

    NASA Astrophysics Data System (ADS)

    Nagendra, C. L.; Thutupalli, G. K. M.; Mohan, S.

    1989-05-01

    The development of non-quarter-wave IR ARCs for the Ge optics of space electrooptic hardware is described. A novel design-optimization method is applied in which the geometrical thicknesses of the ARC layers are calculated analytically (as explained by Nagendra, 1987). Two ARCs are developed: a three-layer system (ThF4/Ge/ThF4) for use at 7-12 microns and a two-layer system (CdTe/CdSe) for 14-16 microns. The ARCs are deposited in a vacuum-evaporation facility and subjected to optical and durability testing. The results are presented in graphs, and it is demonstrated that the ARCs are durable and transparent over the desired wavelength range and have spectral transmittance characteristics in good agreement with the theoretically predicted values.

  4. Analysis on laser-induced transient damage behavior in multilayer coating

    NASA Astrophysics Data System (ADS)

    Lifeng, Du; Bo, Fu; Fengyu, Li; Rongzhu, Zhang

    2016-01-01

    Based on the ionization theory and the Drude model of free electron gas, transient damage principle of the anti-reflection coating under ultrashort pulses are analyzed. Specifically, the damage of an anti-reflection coating designed by ZnS/SiO2 materials is calculated. The results show that during the irradiation process the parameters, such as the refractive index, the electric field and the free electron density, should impact on each other. The coupling relationship between these parameters causes the change in the refractive index, which further leads to the decrease of transmittance of anti-reflection coating from 0.96 to 0.01. In addition, the coupling relationship causes the repartition of free electron density constantly, which eventually leads to the external damage of anti-reflection coating.

  5. Tunable reflection minima of nanostructured antireflective surfaces

    NASA Astrophysics Data System (ADS)

    Boden, S. A.; Bagnall, D. M.

    2008-09-01

    Broadband antireflection schemes for silicon surfaces based on the moth-eye principle and comprising arrays of subwavelength-scale pillars are applicable to solar cells, photodetectors, and stealth technologies and can exhibit very low reflectances. We show that rigorous coupled wave analysis can be used to accurately model the intricate reflectance behavior of these surfaces and so can be used to explore the effects of variations in pillar height, period, and shape. Low reflectance regions are identified, the extent of which are determined by the shape of the pillars. The wavelengths over which these low reflectance regions operate can be shifted by altering the period of the array. Thus the subtle features of the reflectance spectrum of a moth-eye array can be tailored for optimum performance for the input spectrum of a specific application.

  6. Anti-reflective nanoporous silicon for efficient hydrogen production

    DOEpatents

    Oh, Jihun; Branz, Howard M

    2014-05-20

    Exemplary embodiments are disclosed of anti-reflective nanoporous silicon for efficient hydrogen production by photoelectrolysis of water. A nanoporous black Si is disclosed as an efficient photocathode for H.sub.2 production from water splitting half-reaction.

  7. Simple fabrication of an antireflective hemispherical surface structure using a self-assembly method for the terahertz frequency range.

    PubMed

    Kim, Dae-Seon; Kim, Dong-Ju; Kim, Dong-Hyun; Hwang, Sehyun; Jang, Jae-Hyung

    2012-07-01

    A hemispherical surface structure was fabricated on a sapphire substrate by utilizing a self-assembly and spin-coating process for a terahertz (THz) antireflection coating. The self-assembled glass spheres and spin-coated material led to a gradual change in the effective refractive index. The aspect ratio of the hemispherical surface structure was controlled easily by adjusting the thickness of the B-staged bisbenzocyclobutene used as a coating. The reflectance of the fabricated hemispherical surface structure, having a period of 140 μm, exhibited low reflectance and low Fabry-Perot resonance in a THz spectral range from 0.1 to 1.9 THz. PMID:22743514

  8. Design and fabrication of antireflective GaN subwavelength grating structures using periodic silica sphere monolayer array patterning

    NASA Astrophysics Data System (ADS)

    Ko, Yeong Hwan; Yu, Jae Su

    2013-12-01

    We designed and fabricated gallium nitride (GaN) subwavelength grating (SWG) structures on GaN/sapphire via patterning using the periodic silica sphere monolayer array as an etch mask and a subsequent dry etching for efficient antireflection coatings. Theoretical optimization of GaN SWG structures was performed in terms of their geometrical parameters by the rigorous coupled-wave analysis simulation using a theoretical structural model. The bullet-like parabola-shaped SWGs with a large height-to-diameter ratio ( R H/D) yielded good broadband and wide-angle antireflective surface properties. Considering the R H/D, the GaN SWG structure using 320-nm silica spheres theoretically and experimentally exhibited the most efficient antireflection property because it provided a linearly graded effective refractive index profile with relatively long relaxation length. For various geometries of the fabricated GaN SWGs on GaN/sapphire, the calculated reflectance results showed a similar tendency with the experimental results.

  9. Si/PEDOT:PSS Hybrid Solar Cells with Advanced Antireflection and Back Surface Field Designs

    NASA Astrophysics Data System (ADS)

    Sun, Yiling; Yang, Zhenhai; Gao, Pingqi; He, Jian; Yang, Xi; Sheng, Jiang; Wu, Sudong; Xiang, Yong; Ye, Jichun

    2016-08-01

    Molybdenum oxide (MoO3) is one of most suitable antireflection (AR) layers for silicon/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (Si/PEDOT:PSS) hybrid solar cells due to its well-matched refractive index (2.1). A simulation model was employed to predict the optical characteristics of Si/PEDOT:PSS hybrid solar cells with the MoO3 layers as antireflection coatings (ARCs), as well as to analyze the loss in current density. By adding an optimum thickness of a 34-nm-thick ARC of MoO3 on the front side and an effective rear back surface field (BSF) of phosphorus-diffused N + layer at the rear side, the hybrid cells displayed higher light response in the visible and near infrared regions, boosting a short-circuit current density ( J sc) up to 28.7 mA/cm2. The average power conversion efficiency (PCE) of the Si/PEDOT:PSS hybrid solar cells was thus increased up to 11.90 %, greater than the value of 9.23 % for the reference devices.

  10. High efficiency triple-junction solar cells employing biomimetic antireflective structures

    NASA Astrophysics Data System (ADS)

    Chiu, Meng-Yih; Chang, Chia-Hua; Chang, Feng-Yu; Yu, Peichen

    2011-02-01

    In this work, we demonstrate a thorough device design, fabrication, characterization, and analysis of biomimetic antireflective structures implemented on a Ga0.5In0.5P/GaAs/Ge triple-junction solar cell. The sub-wavelength structures are fabricated on a silicon nitride passivation layer using polystyrene nanosphere lithography followed by anisotropic etching. The fabricated structures enhance optical transmission in the ultraviolet wavelength range, compared to a conventional single-layer antireflective coating (ARC). The transmission improvement contributes to the enhanced photocurrent, which is also verified by the external quantum efficiency characterization of fabricated solar cells. Under one-sun illumination, the short-circuit current of a cell with a biomimetic structures is enhanced by 24.1% and 2.2% due to much improved optical transmission and current matching, compared to cells without an ARC and with a conventional ARC, respectively. Further optimizations of the biomimetic structures including the periodicity and etching depth are conducted by performing comprehensive calculations based on a rigorous couple-wave analysis method.

  11. Optical properties of chitin: surface-enhanced Raman scattering substrates based on antireflection structures on cicada wings

    NASA Astrophysics Data System (ADS)

    Stoddart, P. R.; Cadusch, P. J.; Boyce, T. M.; Erasmus, R. M.; Comins, J. D.

    2006-02-01

    The transparent wings of some cicada species present ordered arrays of papillary structures with a spacing of approximately 200 nm. These structures serve an antireflection function, with optical transmission peaking at a value of approximately 98% and rising above 90% over a broad band from 450 to 2500 nm. The dimensions of the papillae are comparable to the roughness scale of surface-enhanced Raman scattering (SERS) substrates. SERS measurements performed on silver- and gold-coated wings display enhancement factors of approximately 106 with no apparent background contribution from the wing.

  12. Nanostructure surface design for broadband and angle-independent antireflection

    NASA Astrophysics Data System (ADS)

    Huang, Yi Fan; Chattopadhyay, Surojit

    2013-01-01

    Three different antireflecting structures (ARS), namely, single-diameter nanorods, dual-diameter nanorods, and biomimetic nanotips (resembling moth-eye's submicrostructures) were compared to each other analytically for their reflectivities, using finite difference time domain calculations. Simulation results establish the biomimetic nanotips as better ARS than the others, in the visible and near-infrared wavelength zone and over a wider angle of incidence. The reflectance values in the nanotips are significantly lower compared to both types of nanorods and also the planar silicon below the Brewster angle (˜75 deg). The low antireflection translated to enhanced optical absorption in these subwavelength structures. A general antireflection design rule emerged from the simulation results.

  13. Optimized antireflective silicon nanostructure arrays using nanosphere lithography

    NASA Astrophysics Data System (ADS)

    Lee, Dohaeng; Bae, Jiwoong; Hong, Soonwook; Yang, Hwichul; Kim, Young-Beom

    2016-05-01

    Broadband optical antireflective arrays of sub-wavelength structures were fabricated on silicon substrates using colloidal nanosphere lithography in conjunction with reactive ion etching. The morphology of the nanostructures, including the shape, base diameter and height, was precisely controlled by modifying the conventional process of nanosphere lithography. We investigated their effects on the optical characteristics based on experimentally measured reflectance performance. The Si nanostructure arrays demonstrated optical antireflection performance with an average reflectance of about 1% across the spectral range from 300 to 800 nm, i.e. near-ultraviolet to visible wavelengths. This fabrication method can be used to create a large surface area and offers a promising approach for antireflective applications.

  14. Broadband-antireflective hybrid nanopillar array for photovoltaic application

    SciTech Connect

    Watanabe, Keiji Yamamoto, Jiro; Tsuchiya, Ryuta

    2015-08-28

    Subwavelength structures such as nanopillars, nanoholes, and nanodomes have recently attracted considerable attention as antireflective structures for solar cells. Recent studies on the optical property of nanopillar array revealed that the reflection minimum is related to the diameter, the pitch, and the height of nanopillars. Here, we investigate the “hybrid” nanopillar array, which is composed of different diameters of nanopillars. Finite differential time domain simulations revealed that the photogeneration in a hybrid nanopillar array is spatially heterogeneous: carriers are generated mainly in the narrower pillars for short-wavelength incident light and in the thicker pillars for long-wavelength light, respectively. Hybrid silicon nanopillar arrays fabricated by using electron beam lithography and dry etching show excellent broadband antireflection property. Hybrid nanopillar array is thus highly promising for next-generation antireflection for photovoltaic applications.

  15. Optimized antireflective silicon nanostructure arrays using nanosphere lithography.

    PubMed

    Lee, Dohaeng; Bae, Jiwoong; Hong, Soonwook; Yang, Hwichul; Kim, Young-Beom

    2016-05-27

    Broadband optical antireflective arrays of sub-wavelength structures were fabricated on silicon substrates using colloidal nanosphere lithography in conjunction with reactive ion etching. The morphology of the nanostructures, including the shape, base diameter and height, was precisely controlled by modifying the conventional process of nanosphere lithography. We investigated their effects on the optical characteristics based on experimentally measured reflectance performance. The Si nanostructure arrays demonstrated optical antireflection performance with an average reflectance of about 1% across the spectral range from 300 to 800 nm, i.e. near-ultraviolet to visible wavelengths. This fabrication method can be used to create a large surface area and offers a promising approach for antireflective applications. PMID:27087196

  16. Design, fabrication, and measured performance of anti-reflecting surface textures in infrared transmitting materials

    NASA Astrophysics Data System (ADS)

    Hobbs, Douglas S.; MacLeod, Bruce D.

    2005-05-01

    Rugged infrared transmitting materials have a high refractive index, which leads to large reflection losses. Multi-layer thin-film coatings designed for anti-reflection (AR), exhibit good performance, but have limited bandwidths, narrow acceptance angles, polarization effects, high costs, and short lifetimes in harsh environments. Many aerospace and military applications requiring high optical transmission, durability, survivability, and radiation resistance, are inadequately addressed by thin-film coating technology. Surface relief microstructures have been shown to be an effective alternative to thin-film AR coatings in many infrared and visible-band applications. These microstructures, etched directly into the window surface and commonly referred to as "Motheye" textures, impart an optical function that minimizes surface reflections without compromising the inherent durability of the window material. Reflection losses are reduced to a minimum for broad-band light incident over a wide angular range. For narrow-band applications such as laser communications, a simpler type of AR surface structure called a sub-wavelength, or "SWS" surface, is used. In general, both the Motheye and SWS surface textures will exhibit the same characteristics as the bulk material with respect to durability, thermal issues, and radiation resistance. The problems associated with thin-film coating adhesion and stress, are thus eliminated by design. Optical performance data for AR structures fabricated in fused silica, sapphire, Clear ZnS, ZnSe, cadmium zinc telluride (CZT), silicon, and germanium, will be presented.

  17. Structurally colored surfaces with antireflective, self-cleaning, and antifogging properties.

    PubMed

    Du, Xin; He, Junhui

    2012-09-01

    This article describes a simple method to fabricate uniform porous antireflective (AR) coatings composed of nanoflakes on the surface of soda lime glass through one-step hydrothermal alkali (NaOH) etching process. Experimental conditions including reaction temperature, NaOH concentration, and reaction time were investigated to find the optimal etching conditions, and the maximum transmittance increases from 90.5% to 98.5%. The coating thickness increases with increase in the NaOH concentration, leading to the tunable red-shift of transmission and reflection spectra in the UV and entire visible range. And the corresponding uniform structural reflected colors varying from gray, pale yellow, yellow, pink, blue to pale blue are observed when the etched glasses are viewed in reflected light. The relationship of coating thickness, transmittance, reflectance, and reflected color was obtained and discussed. The etched glass after introducing TiO(2) component onto the porous coating had AR, self-cleaning (superhydrophilic and photocatalytic) and antifogging properties. It is conceivable that such etched glasses would have broad potential applications in optical devices, solar cells, light emitting diodes, and varied window glasses. PMID:22717084

  18. Fabrication and performance of polymer-nanocomposite anti-reflective thin films deposited by RIR-MAPLE

    SciTech Connect

    Singaravelu, S.; Mayo, D. C.; Park, H-. K.; Schriver, K. E.; Klopf, John M.; Kelley, Michael J.; Haglund, R. F.

    2014-07-01

    Design of polymer anti-reflective (AR) optical coatings for plastic substrates is challenging because polymers exhibit a relatively narrow range of refractive indices. Here, we report synthesis of a four-layer AR stack using hybrid polymer: nanoparticle materials deposited by resonant infrared matrix-assisted pulsed laser evaporation. An Er: YAG laser ablated frozen solutions of a high-index composite containing TiO2 nanoparticles and poly(methylmethacrylate) (PMMA), alternating with a layer of PMMA. The optimized AR coatings, with thicknesses calculated using commercial software, yielded a coating for polycarbonate with transmission over 97 %, scattering <3 %, and a reflection coefficient below 0.5 % across the visible range, with a much smaller number of layers than would be predicted by a standard thin film calculation. The TiO2 nanoparticles contribute more to the enhanced refractive index of the high-index layers than can be accounted for by an effective medium model of the nanocomposite.

  19. An Antireflective Nanostructure Array Fabricated by Nanosilver Colloidal Lithography on a Silicon Substrate

    PubMed Central

    2010-01-01

    An alternative method is presented for fabricating an antireflective nanostructure array using nanosilver colloidal lithography. Spin coating was used to produce the multilayered silver nanoparticles, which grew by self-assembly and were transformed into randomly distributed nanosilver islands through the thermodynamic action of dewetting and Oswald ripening. The average size and coverage rate of the islands increased with concentration in the range of 50–90 nm and 40–65%, respectively. The nanosilver islands were critically affected by concentration and spin speed. The effects of these two parameters were investigated, after etching and wet removal of nanosilver residues. The reflection nearly disappeared in the ultraviolet wavelength range and was 17% of the reflection of a bare silicon wafer in the visible range. PMID:21076677

  20. Simulation analysis of GaN microdomes with broadband omnidirectional antireflection for concentrator photovoltaics

    NASA Astrophysics Data System (ADS)

    Han, Lu; Zhao, Hongping

    2014-04-01

    Microdome structures are analyzed as surface topology to reduce surface reflection over a broad spectral range and wide light incidence angle for concentrator photovoltaics application. Three dimensional finite difference time domain method was used to accurately calculate the surface reflection and transmission for surface topologies with different feature sizes and aspect ratios. Studies show that the use of GaN microdomes will lead to a significant reduction of the surface reflection over a broad wavelength range and wide incidence angle range. The surface reflection significantly depends on the surface structure feature size and geometrical shape. The design of the GaN microdomes provides flexibility to tune the structure in order to obtain the minimum surface reflection for different designs of concentrator optical systems. The surface reflections of the GaN microdomes are compared with that of the conventional flat surface as well as the one with antireflection coating.

  1. Mechanically robust, thermally stable, broadband antireflective, and superhydrophobic thin films on glass substrates.

    PubMed

    Xu, Ligang; Geng, Zhi; He, Junhui; Zhou, Gang

    2014-06-25

    In this study, we developed a simple and versatile strategy to fabricate hierarchically structured lotus-leaf-like superhydrophobic thin films. The thin films are broadband antireflective, and the average transmittance of coated glass substrates reached greater than 95% in the wavelength range of 530-1340 nm, in contrast to 92.0% for bare glass substrate. The thin film surface shows a static water contact angle of 162° and a sliding angle less than 4°. Moreover, the thin film is thermally stable up to 300 °C, and shows remarkable stability against strong acid, strong alkali, water drop impact, and sand impact abrasion, while retaining its superhydrophobicity. Further, the thin film can pass the 3H pencil hardness test. The current approach may open a new avenue to a variety of practical applications, including windshields, eyeglasses, windows of high rise buildings and solar cells, etc. PMID:24848810

  2. Antireflective indium-tin-oxide nanobranches for efficient organic solar cells

    NASA Astrophysics Data System (ADS)

    Ham, Juyoung; Park, Jae Yong; Dong, Wan Jae; Jung, Gwan Ho; Yu, Hak Ki; Lee, Jong-Lam

    2016-02-01

    Indium tin oxide (ITO) nanobranched structures with low reflectance have been designed for application to organic solar cells. The ITO nanobranches are deposited on the front surface of glass without damages to organic active layer by using an electron beam deposition. Through a finite-difference time-domain, we find that the field intensity in the glass region is enhanced with ITO nanobranches. Consequently, the number of incident photons induces strong absorption within the PTB7-PC70BM active layer, leading to the enhanced short circuit current density (Jsc). Compared with a flat device (power conversion efficiency (PCE) = 6.53%, Jsc = 13.3 mA/cm2), improved PCE of 7.09% is achieved in an antireflection coating, which is mainly due to the increased Jsc of 14.2 mA/cm2.

  3. Self-organized, effective medium Black Silicon for infrared antireflection

    NASA Astrophysics Data System (ADS)

    Steglich, Martin; Käsebier, Thomas; Schrempel, Frank; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2015-03-01

    Statistical Black Silicon antireflection structures for the mid-infrared spectral region, fabricated by Inductively Coupled Plasma Reactive Ion Etching, are investigated. Upon variation of etch duration scaling of the structure morphologies is observed and related to the optical losses in specular transmittance. By means of statistical morphology analysis, an effective medium criterion for the examined structures is derived that can be used as a design rule for maximizing sample transmittance at a given wavelength. To obtain Black Silicon antireflection structures with elevated bandwidth, an additional deep-etch step is proposed and demonstrated.

  4. Broadband antireflective surface-relief structure for THz optics.

    PubMed

    Brückner, Claudia; Pradarutti, Boris; Stenzel, Olaf; Steinkopf, Ralf; Riehemann, Stefan; Notni, Gunther; Tünnermann, Andreas

    2007-02-01

    The requirements for a broadband antireflective structure in the THz spectral region are derived. Optimized structural parameters for a surface-relief grating adapted to the spectrum of an intended THz pulse are deduced. The effect of a structure fabricated into Topas((R)) by a single-point diamond-turning process is demonstrated. PMID:19532301

  5. Optical coatings for laser fusion applications

    SciTech Connect

    Lowdermilk, W.H.; Milam, D.; Rainer, F.

    1980-04-24

    Lasers for fusion experiments use thin-film dielectric coatings for reflecting, antireflecting and polarizing surface elements. Coatings are most important to the Nd:glass laser application. The most important requirements of these coatings are accuracy of the average value of reflectance and transmission, uniformity of amplitude and phase front of the reflected or transmitted light, and laser damage threshold. Damage resistance strongly affects the laser's design and performance. The success of advanced lasers for future experiments and for reactor applications requires significant developments in damage resistant coatings for ultraviolet laser radiation.

  6. Microstructures, optical and photoelectric conversion properties of spherical silicon solar cells with anti-reflection SnOx:F thin films

    NASA Astrophysics Data System (ADS)

    Oku, Takeo; Kanayama, Masato; Ono, Yuji; Akiyama, Tsuyoshi; Kanamori, Youichi; Murozono, Mikio

    2014-01-01

    The microstructures and optical and photoelectric conversion properties of spherical silicon (Si) solar cells were investigated and discussed. The surface of the spherical Si with a pn junction provided high crystallinity, and the lattice constant of the center of Si spheres is larger than that of the surface, which would be due to the lattice distortion by defect structures at the center of Si. The conversion efficiencies of spherical Si solar cells coated with SnOx:F anti-reflection thin films were improved by annealing. The optical absorption and fluorescence of the solar cells increased, and the lattice constants of SnOx:F anti-reflection layers decreased after annealing. The mechanisms of chemical reactions at the Si/metal interface were also discussed.

  7. Properties of conductive coatings for thermal control mirrors and solar cell covers

    NASA Technical Reports Server (NTRS)

    Joslin, D. E.; Kan, H. K. A.

    1975-01-01

    Conductive transparent coatings applied to the dielectric surfaces of a spacecraft offer the possibility of distributing charge uniformly over the entire spacecraft surface. Optical and electrical measurements of such a coating as a function of temperature are described. These results are used in considering the impact of a conductive coating on the absorptance of thermal control mirrors and on the transmittance of solar cell cover glass, which can be improved by the application of an antireflection coating.

  8. Antireflection and SiO2 Surface Passivation by Liquid-Phase Chemistry for Efficient Black Silicon Solar Cells: Preprint

    SciTech Connect

    Yuan, H. C.; Oh, J.; Zhang, Y.; Kuznetsov, O. A.; Flood, D. J.; Branz, H. M.

    2012-06-01

    We report solar cells with both black Si antireflection and SiO2 surface passivation provided by inexpensive liquid-phase chemistry, rather than by conventional vacuum-based techniques. Preliminary cell efficiency has reached 16.4%. Nanoporous black Si antireflection on crystalline Si by aqueous etching promises low surface reflection for high photon utilization, together with lower manufacturing cost compared to vacuum-based antireflection coating. Ag-nanoparticle-assisted black Si etching and post-etching chemical treatment recently developed at NREL enables excellent control over the pore diameter and pore separation. Performance of black Si solar cells, including open-circuit voltage, short-circuit current density, and blue response, has benefited from these improvements. Prior to this study, our black Si solar cells were all passivated by thermal SiO2 produced in tube furnaces. Although this passivation is effective, it is not yet ideal for ultra-low-cost manufacturing. In this study, we report, for the first time, the integration of black Si with a proprietary liquid-phase deposition (LPD) passivation from Natcore Technology. The Natcore LPD forms a layer of <10-nm SiO2 on top of the black Si surface in a relatively mild chemical bath at room temperature. We demonstrate black Si solar cells with LPD SiO2 with a spectrum-weighted average reflection lower than 5%, similar to the more costly thermally grown SiO2 approach. However, LPD SiO2 provides somewhat better surface-passivation quality according to the lifetime analysis by the photo-conductivity decay measurement. Moreover, black Si solar cells with LPD SiO2 passivation exhibit higher spectral response at short wavelength compared to those passivated by thermally grown SiO2. With further optimization, the combination of aqueous black Si etching and LPD could provide a pathway for low-cost, high-efficiency crystalline Si solar cells.

  9. Anti-reflective device having an anti-reflective surface formed of silicon spikes with nano-tips

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam (Inventor); Manohara, Harish (Inventor); Mobasser, Sohrab (Inventor); Lee, Choonsup (Inventor)

    2011-01-01

    Described is a device having an anti-reflection surface. The device comprises a silicon substrate with a plurality of silicon spikes formed on the substrate. A first metallic layer is formed on the silicon spikes to form the anti-reflection surface. The device further includes an aperture that extends through the substrate. A second metallic layer is formed on the substrate. The second metallic layer includes a hole that is aligned with the aperture. A spacer is attached with the silicon substrate to provide a gap between an attached sensor apparatus. Therefore, operating as a Micro-sun sensor, light entering the hole passes through the aperture to be sensed by the sensor apparatus. Additionally, light reflected by the sensor apparatus toward the first side of the silicon substrate is absorbed by the first metallic layer and silicon spikes and is thereby prevented from being reflected back toward the sensor apparatus.

  10. Update on diamond and diamond-like carbon coatings

    NASA Astrophysics Data System (ADS)

    Lettington, Alan H.

    1990-10-01

    This paper reviewed the infrared uses of diamond-like carbon thin films and the potential uses of synthetic diamond layers. Diamond-like carbon is used widely as a protective anti-reflection coating for exposed germanium infrared windows and lenses and as thin protective coatings for front surface aluminium mirrors. This material is also used in protective anti-reflective coatings for zinc sulphide as the outer thin film in multi-layer designs incorporating variable index intermediate layers of germanium carbide. The maximum thickness of diamond-like carbon that can be used is often limited by the stress induced in the layer through the method of deposition and by the absorption present in the basic material. This stress and absorption can be far lower in synthetic diamond layers but there are now problems associated with the high substrate temperatures, difficulties in coating large areas uniformly and problems arising from surface scattering and low deposition rates.

  11. Long-pulse laser-induced damage in an optical anti-reflective film: II. Experimental research

    NASA Astrophysics Data System (ADS)

    Li, Changli; Ma, Yao; Wang, Di; Wang, Zhiyang; Zhang, Xihe; Liu, Haiming

    2014-12-01

    In order to verify the result of theoretical analysis about long-pulse flat-topped multi-Gaussian laser-induced damage in an optical anti-reflection film with HfO2/SiO2 composite film coating on a BK7 substrate (BK7:HfO2/SiO2), an experimental system was built, which carried out the experiment and analysis, focusing on the pulse-length 1.0 ms, flat-topped laser-induced damage. The result shows that the thermal effect is the main reason for damage under the long-pulse flat-topped laser. Moreover, the stripping and shedding occur because of the heating stress of the film happening at an early stage of the laser irradiation. However, the crack happens at laser irradiation termination. The correctness of the theoretical analysis results is verified.

  12. Light Confinement-Induced Antireflection of ZnO Nanocones

    SciTech Connect

    Lee, Sang Hyun; Jellison Jr, Gerald Earle; Duty, Chad E; Xu, Jun

    2011-01-01

    The antireflective features of aperiodic vertical aligned ZnO nanocones on Si wafer were studied both experimentally and theoretically through comparison with planar ZnO films on Si substrates and bare Si substrates. The measured diffuse reflectance spectra show that the nanocone-based texture reduces the light reflection in a broad spectral range, and is much more effective than the planar textures. The numerical simulations exhibit a good agreement with the experimental data and suggest that the light confinement inside nanocones by controlling the diameters can bring further improvement of light absorption into Si.

  13. Self-decorated Au nanoparticles on antireflective Si pyramids with improved hydrophobicity

    NASA Astrophysics Data System (ADS)

    Saini, C. P.; Barman, A.; Kumar, M.; Satpati, B.; Som, T.; Kanjilal, A.

    2016-04-01

    Post-deposition annealing mediated evolution of self-decorated Au nanoparticles (NPs) on chemically etched Si pyramids is presented. A distinct transformation of Si surfaces from hydrophilic to hydrophobic is initially found after chemical texturing, showing an increase in contact angle (CA) from 58° to 98° (±1°). Further improvement of hydrophobicity with CA up to ˜118° has been established after annealing a 10 nm thick Au-coated Si pyramids at 400 °C that led to the formation of Au NPs on Si facets along with self-ordering at the pyramid edges. Detailed x-ray diffraction studies suggest the evolution of crystalline Au NPs on strained Si facets. Microstructural studies, however, indicate no mixing of Au and Si atoms at the Au/Si interfaces, instead of forming Au nanocrystals at 400 °C. The improved hydrophobicity of Si pyramids, even with Au NPs can be explained in the light of a decrease in solid fractional surface area according to Wenzel's model. Moreover, a sharp drop in specular reflectance from Si pyramids in the range of 300-800 nm, especially in the ultraviolet region up to ˜0.4% is recorded in the presence of Au NPs by ultraviolet-visible spectroscopy, reflecting the possible use in photovoltaic devices with improved antireflection property.

  14. Antireflection subwavelength gratings on optical fiber tips fabricated by a dedicated UV nano imprint lithography system

    NASA Astrophysics Data System (ADS)

    Kanamori, Yoshiaki; Okochi, Masaaki; Hane, Kazuhiro

    2015-02-01

    Antireflection (AR) layers at the tips of optical fibers are indispensable in order to reduce propagation loss and optical noise. Conventional thin-film AR layers have problems about cost due to vacuum apparatus usage in the fabrication and requirement of many thin-film layers to obtain excellent AR characteristics. Thus, easy AR coating methods are needed to reduce Fresnel reflection. AR structures consisting of subwavelength gratings (SWGs), which have periodic structures with the periods smaller than operating wavelengths, have been extensively investigated. Desired refractive index to realize the ideal AR condition can be obtained by SWGs. Nano imprint lithography (NIL) is known as the low cost fabrication technology of SWGs. However, it is difficult to carry out an NIL process on the tips of flexible and long optical fibers. In this study, we developed a dedicated UV-NIL system for optical fiber end-faces. An SWG with a period of 700 nm, a width of 560 nm, and a height of 250 nm was successfully fabricated at the tip of a single-mode optical fiber for optical communications system. We evaluated that reflectance decreased by using the SWG over measured spectral range. For example, reflectance decreased to 0.2% at a wavelength of 1550 nm.

  15. Laser damage resistant anti-reflection microstructures in Raytheon ceramic YAG, sapphire, ALON, and quartz

    NASA Astrophysics Data System (ADS)

    Hobbs, Douglas S.; MacLeod, Bruce D.; Sabatino, Ernest, III; Hartnett, Thomas M.; Gentilman, Richard L.

    2011-06-01

    A study of the laser induced damage threshold (LiDT) of anti-reflection (AR) microstructures (ARMs) built in the end facets of metal ion doped yttrium aluminum garnet (YAG) laser gain material, has been conducted. Test samples of undoped and ytterbium-doped polycrystalline YAG produced by Raytheon Company were processed with ARMs in one surface and subjected to standardized pulsed LiDT testing at the near-infrared (NIR) wavelength of 1064nm. As received YAG samples with a simple commercial polish were also submitted to the damage tests for comparison, along with YAG samples that were treated with a single layer thin-film AR coating designed for maximum transmission at 1064nm. Additional samples of single crystal sapphire and quartz, and polycrystalline ALONTM windows were prepared with thin-film AR coatings and ARMs textures to expand the 1064nm laser damage testing to other important NIR transmitting materials. It was found that the pulsed laser damage resistance of ARMs textured ceramic YAG windows is 11 J/cm2, a value that is 43% higher than untreated ceramic YAG windows, suggesting that ARMs fabrication removed residual sub-surface damage, a factor that has been shown to be important for increasing the damage resistance of an optic. This conclusion is also supported by the high damage threshold values found with the single layer AR coatings on ceramic YAG where the coatings may have shielded the sub-surface polishing damage. Testing results for the highly polished sapphire windows also support the notion that better surface preparation produces higher damage resistance. The damage threshold for untreated sapphire windows exceeded 32 J/cm2 for one sample with an average of 27.5 J/cm2 for the two samples tested. The ARMs-treated sapphire windows had similar damage thresholds as the untreated material, averaging 24.9 J/cm2, a value 1.5 to 2 times higher than the damage threshold of the thin film AR coated sapphire windows.

  16. Design of antireflection film for underwater laser imaging system

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-peng; Sun, Jing-hua

    2011-08-01

    In the underwater imaging system, When the light reflected from the surface of something tested through the water medium gets to the surface of the imaging lens or when the light through the air gets to the surface of the imaging lens, the reflection will happen, it leads that the light detectors receives the light less than before. The loss of light energy leads to the decrease of image illumination. Meanwhile, some of the reflected light becomes of stray light to the surface of image, and then that the contrast grade of image gets lower influences the quality of imaging. Hence, in order to minimize the impact of image quality, a system for the underwater antireflection film to improve image quality should be designed. This paper is based on the optical film-designed theory, for the blue-green light whose center wavelength is 532nm, the antireflection films of both air-optical glass interface and seawater-optical glass interface are designed, and the reflectivity curve and the their calculated results are given.

  17. Bio-inspired antireflective hetero-nanojunctions with enhanced photoactivity

    NASA Astrophysics Data System (ADS)

    Qi, Dianpeng; Zheng, Liyan; Cao, Xuebo; Jiang, Yueyue; Xu, Hongbo; Zhang, Yanyan; Yang, Bingjie; Sun, Yinghui; Hng, Huey Hoon; Lu, Nan; Chi, Lifeng; Chen, Xiaodong

    2013-11-01

    A bio-inspired antireflective hetero-nanojunction structure has been fabricated by the hydrothermal growth of ZnO nanorods on silicon micro-pyramids. It has been shown that this structure suppresses light reflection more effectively resulting in a high photocurrent response and good charge separation simultaneously. The strategy provides a means to enhance solar energy conversion.A bio-inspired antireflective hetero-nanojunction structure has been fabricated by the hydrothermal growth of ZnO nanorods on silicon micro-pyramids. It has been shown that this structure suppresses light reflection more effectively resulting in a high photocurrent response and good charge separation simultaneously. The strategy provides a means to enhance solar energy conversion. Electronic supplementary information (ESI) available: HRTEM image and XRD pattern of a ZnO nanorod; schematic representation of the photoanode behavior, as well as the concentration change of rhodamine 6G through the photodegradation process over many repeats. See DOI: 10.1039/c3nr04011a

  18. Optical characterization of anti reflective sol-gel coatings fabricated using dip coating method

    NASA Astrophysics Data System (ADS)

    Melninkaitis, A.; Juškevičius, K.; Maciulevičius, M.; Sirutkaitis, V.; Beganskienė, A.; Kazadojev, I.; Kareiva, A.; Perednis, D.

    2007-01-01

    In recent years, there has been a growing interest in further development of sol-gel method which can produce ceramics and glasses using chemical precursors at relative low-temperatures. The applications for sol-gel derived products are numerous. Department of General and Inorganic Chemistry with Laser Research Center of Vilnius University and Institute of Physics continues an ongoing research effort on the synthesis, deposition and characterization of porous solgel. Our target is highly optically resistant anti-reflective (AR) coatings for general optics and nonlinear optical crystals. In order to produce AR coatings a silica (SiO II) sol-gel has been dip coated on the set of fused silica substrates. The optical properties and structure of AR-coatings deposited from hydrolysed tetraethylorthosilicate (TEOS) sol were characterized in detail in this study. The influence of different parameters on the formation of colloidal silica antireflective coatings by dip-coating technique has been investigated. All samples were characterized performing, transmission electron microscopy, UV-visible spectroscopy, atomic force microscopy, ellipsometric, total scattering and laser-induced damage threshold measurements. Herewith we present our recent results on synthesis of sol-gel solvents, coating fabrication and characterization of their optical properties.

  19. Application of physical gradient index (Moth-Eye) structures to ALON windows as a durable anti-reflection treatment

    NASA Astrophysics Data System (ADS)

    Agarwal, Neeta; Goldman, Lee M.; Sastri, Suri A.; Ondercin, Robert J.; Kobrin, Paul

    2009-05-01

    The optical performance of windows and domes are subject to degradation from rain and sand erosion damage in harsh flight environments. While durable window and dome materials, such as ALON®, spinel and sapphire are more or less impervious to rain and sand erosion damage in the captive carry environments, the coatings use to provide antireflection (AR) function are not. Rain and/or sand erosion damage of the outer AR coating leads to degradation of the windows optical performance, even when the underlying window itself is not damaged. Surmet has been working on design and development of physical gradient index (Moth- Eye) structures based AR surfaces etched directly into the surface of the ALON substrate. By eliminating the need for less durable coating materials, these structures offer high optical performance without compromising durability. The difficulty of this approach is that the same durability that makes ALON impervious to erosion damage makes it very difficult to etch. Processes have been developed at Surmet which facilitate the etching of fine deep features into ALON surfaces required for broadband AR function. Recent results will be presented.

  20. Optimization of contaminated oxide inversion layer solar cell. [considering silicon oxide coating

    NASA Technical Reports Server (NTRS)

    Call, R. L.

    1976-01-01

    Contaminated oxide cells have been fabricated with efficiencies of 8.6% with values of I sub sc = 120 ma, V sub oc = .54 volts, and curve factor of .73. Attempts to optimize the fabrication step to yield a higher output have not been successful. The fundamental limitation is the inadequate antireflection coating afforded by the silicon dioxide coating used to hold the contaminating ions. Coatings of SiO, therefore, were used to obtain a good antireflection coating, but the thinness of the coatings prevented a large concentration of the contaminating ions, and the cells was weak. Data of the best cell were .52 volts V sub oc, 110 ma I sub sc, .66 CFF and 6.7% efficiency.

  1. Broadband antireflection for a high-index substrate using SiN x /SiO2 by inductively coupled plasma chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Lim, Kim Peng; Ng, Doris K. T.; Wang, Qian

    2016-03-01

    This paper presents the development of broadband antireflection coating for a high-index substrate such as Si using SiN x /SiO2 by inductively coupled plasma chemical vapour deposition (ICP-CVD). The thin-film design employs a simulated annealing method for a minimal average reflectance over the wavelength range and incidence angles involved, which gives the optimized refractive index and thickness of each layer of the thin-film stack under different layer numbers. Using ICP-CVD, the SiN x material system is optimized by tuning the SiH4/N2 gas ratio. The corresponding thin-film characterization shows the precise refractive index/film thickness control in deposition, and the deposited film also has a low absorption coefficient and smooth surface. The double-layer SiN x /SiO2 coating with the optimized refractive index and thickness for broadband antireflection is demonstrated experimentally. The average reflectance of the Si surface is reduced from ~32% to ~3.17% at normal incidence for a wavelength range from 400 to 1100 nm.

  2. Use of ZnO as antireflective, protective, antibacterial, and biocompatible multifunction nanolayer of thermochromic VO2 nanofilm for intelligent windows

    NASA Astrophysics Data System (ADS)

    Zhou, Huaijuan; Li, Jinhua; Bao, Shanhu; Li, Jian; Liu, Xuanyong; Jin, Ping

    2016-02-01

    A multifunctional VO2/ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. The integration of the antireflective, antioxidative and anti-corrosion functions, and antibacterial performance makes the heterostructure film a promising candidate in the energy-saving smart window. The ZnO thin film as the antireflection layer can markedly boost the solar regulation efficiency (ΔTsol) from 7.7% to 12.2% and possesses excellent luminous transmittance (Tlum-L = 50.3%) in the low-temperature semiconductor phase. The ZnO layer as the protection barrier can not only protect VO2 thin film from oxidation to much toxic V2O5, but also decrease the release of V ions. Besides, the synergistic effect of releasing killing by Zn2+ ions and contact killing by ZnO NPs makes ZnO thin film an outstanding antibacterial coating. In terms of the biological safety, ZnO coating with appropriate film thickness can effectively attenuate the cytotoxicity of VO2 on human HIBEpiC cells. We hope this work can provide new insights for better designing of novel multifunctional VO2-based intelligent energy-saving windows.

  3. The HMDS Coating Flaw Removal Tool

    SciTech Connect

    Monticelli, M V; Nostrand, M C; Mehta, N; Kegelmeyer, L; Johnson, M A; Fair, J; Widmayer, C

    2008-10-24

    In many high energy laser systems, optics with HMDS sol gel antireflective coatings are placed in close proximity to each other making them particularly susceptible to certain types of strong optical interactions. During the coating process, halo shaped coating flaws develop around surface digs and particles. Depending on the shape and size of the flaw, the extent of laser light intensity modulation and consequent probability of damaging downstream optics may increase significantly. To prevent these defects from causing damage, a coating flaw removal tool was developed that deploys a spot of decane with a syringe and dissolves away the coating flaw. The residual liquid is evacuated leaving an uncoated circular spot approximately 1mm in diameter. The resulting uncoated region causes little light intensity modulation and thus has a low probability of causing damage in optics downstream from the mitigated flaw site.

  4. Tailoring room temperature photoluminescence of antireflective silicon nanofacets

    SciTech Connect

    Basu, Tanmoy; Kumar, M.; Ghatak, J.; Som, T.; Kanjilal, A.; Sahoo, P. K.

    2014-09-21

    In this paper, a fluence-dependent antireflection performance is presented from ion-beam fabricated nanofaceted-Si surfaces. It is also demonstrated that these nanofacets are capable of producing room temperature ultra-violet and blue photoluminescence which can be attributed to inter-band transitions of the localized excitonic states of different Si-O bonds at the Si/SiO{sub x} interface. Time-resolved photoluminescence measurements further confirm defect-induced radiative emission from the surface of silicon nanofacets. It is observed that the spectral characteristics remain unchanged, except an enhancement in the photoluminescence intensity with increasing ion-fluence. The increase in photoluminescence intensity by orders of magnitude stronger than that of a planar Si substrate is due to higher absorption of incident photons by nanofaceted structures.

  5. Moth's eye anti-reflection gratings on germanium freeform surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Meng; Shultz, Jason A.; Owen, Joseph D.; Davies, Matthew A.; Suleski, Thomas J.

    2014-09-01

    Germanium is commonly used for optical components in the infrared, but the high refractive index of germanium causes significant losses due to Fresnel reflections. Anti-reflection (AR) surfaces based on subwavelength "moth's eye" gratings provide one means to significantly increase optical transmission. As found in nature, these gratings are conformal to the curved surfaces of lenslets in the eye of the moth. Engineered optical systems inspired by biological examples offer possibilities for increased performance and system miniaturization, but also introduce significant challenges to both design and fabrication. In this paper, we consider the design and fabrication of conformal moth's eye AR structures on germanium freeform optical surfaces, including lens arrays and Alvarez lenses. Fabrication approaches and limitations based on both lithography and multi-axis diamond machining are considered. Rigorous simulations of grating performance and approaches for simulation of conformal, multi-scale optical systems are discussed.

  6. Silicon Nanotips Antireflection Surface for Micro Sun Sensor

    NASA Technical Reports Server (NTRS)

    Bae, Sam Y.; Lee, Choonsup; Mobasser, Sohrab; Manohara, Harish

    2006-01-01

    We have developed a new technique to fabricate antireflection surface using silicon nano-tips for use on a micro sun sensor for Mars rovers. We have achieved randomly distributed nano-tips of radius spanning from 20 nm to 100 nm and aspect ratio of 200 using a two-step dry etching process. The 30(deg) specular reflectance at the target wavelength of 1 (mu)m is only about 0.09 %, nearly three orders of magnitude lower than that of bare silicon, and the hemispherical reflectance is 8%. By changing the density and aspect ratio of these nanotips, the change in reflectance is demonstrated. Using surfaces covered with these nano-tips, the critical problem of ghost images that are caused by multiple internal reflections in a micro sun sensor was solved.

  7. Exploring anti-reflection modes in disordered media.

    PubMed

    Kim, Moonseok; Choi, Wonjun; Yoon, Changhyeong; Kim, Guang Hoon; Kim, Seung-hyun; Yi, Gi-Ra; Park, Q-Han; Choi, Wonshik

    2015-05-18

    Sensing and manipulating targets hidden under scattering media are universal problems that take place in applications ranging from deep-tissue optical imaging to laser surgery. A major issue in these applications is the shallow light penetration caused by multiple scattering that reflects most of incident light. Although advances have been made to eliminate image distortion by a scattering medium, dealing with the light reflection has remained unchallenged. Here we present a method to minimize reflected intensity by finding and coupling light into the anti-reflection modes of a scattering medium. In doing so, we achieved more than a factor of 3 increase in light penetration. Our method of controlling reflected waves makes it readily applicable to in vivo applications in which detector sensors can only be positioned at the same side of illumination and will therefore lay the foundation of advancing the working depth of many existing optical imaging and treatment technologies. PMID:26074528

  8. Biomimetic ‘moth-eye’ anti-reflection boundary for graphene plasmons circuits

    NASA Astrophysics Data System (ADS)

    Zhu, B.; Ren, G.; Cryan, M. J.; Gao, Y.; Li, H.; Wang, Q.; Wan, C.; Jian, S.

    2015-12-01

    In this paper we propose the anti-reflection boundary design for planar graphene plasmons (GPs) circuits based on biomimetic moth-eye structures. The anti-reflection functionalities are investigated by analytical effective medium theory combined with transfer matrix method and numerical finite element method. Both analytical and numerical methods have shown that average reflection losses of 1% can be achieved within the mid-infrared region. Moreover, for plasmons with a very wide incident angle, the performance of such anti-reflection boundary could still be maintained, achieving less than 1% reflection up to 60° incident angle. The proposed moth-eye anti-reflection boundary would be helpful for the future development of high integration GPs circuits.

  9. Efficiency enhancement of flexible organic light-emitting devices by using antireflection nanopillars.

    PubMed

    Ho, Yu-Hsuan; Liu, Chung-Chun; Liu, Shun-Wei; Liang, Hsun; Chu, Chih-Wei; Wei, Pei-Kuen

    2011-05-01

    We present an antireflection structure consisted of irregular nanopillars to increase light extraction efficiency of flexible organic light-emitting devices. The nanopillars were made by imprinting the anodized aluminum oxide on polycarbonate substrates. The thermal viscosity effect formed the nanopillars with tapered shapes. Such nanopillars show excellent antireflection properties for a wide range of incident angles and wavelengths. The normal transmittance was improved from 85.5% to 95.9% for 150-nm-height nanopillars. The transmittance was greatly improved from 52.8% to 89.1% at 60° incident angle. With this antireflection structure, the device efficiency was improved 69% as compared to devices with flat substrates. Due to wide-angle antireflection, the image contrast ratio was also significantly improved. PMID:21643370

  10. Nature Inspired Surface Coatings

    NASA Astrophysics Data System (ADS)

    Rubner, Michael

    2011-04-01

    Materials Scientists more and more are looking to nature for clues on how to create highly functional surface coatings with exceptional properties. The fog harvesting capabilities of the Namib Desert beetle, the beautiful iridescent colors of the hummingbird, and the super water repellant abilities of the Lotus leaf are but a few examples of the amazing properties developed over many years in the natural world. Nature also makes extensive use of the pH-dependent behavior of weak functional groups such as carboxylic acid and amine functional groups. This presentation will explore synthetic mimics to the nano- and microstructures responsible for these fascinating properties. For example, we have demonstrated a pH-induced porosity transition that can be used to create porous films with pore sizes that are tunable from the nanometer scale to the multiple micron scale. The pores of these films, either nano- or micropores, can be reversibly opened and closed by changes in solution pH. The ability to engineer pH-gated porosity transitions in heterostructured thin films has led to the demonstration of broadband anti-reflection coatings that mimic the anti-reflection properties of the moth eye and pH-tunable Bragg reflectors with a structure and function similar to that found in hummingbird wings and the Longhorn beetle. In addition, the highly textured honeycomb-like surfaces created by the formation of micron-scale pores are ideally suited for the creation of superhydrophobic surfaces that mimic the behavior of the self-cleaning lotus leaf. The development of synthetic "backbacks" on immune system cells that may one day ferry drugs to disease sites will also be discussed.

  11. Development and testing of coatings for orbital space radiation environments.

    PubMed

    Pellicori, Samuel F; Martinez, Carol L; Hausgen, Paul; Wilt, David

    2014-02-01

    Specific coating processes and materials were investigated in the quest to develop multilayer coatings with greater tolerance to space radiation exposure. Ultraviolet reflection (UVR) and wide-band antireflection (AR) multilayer coatings were deposited on solar cell covers and test substrates and subsequently exposed to simulated space environments and also flown on the Materials International Space Station Experiment-7 (MISSE-7) to determine their space environment stability. Functional solar cells integrated with these coatings underwent simulated UV and MISSE-7 low earth orbit flight exposure. The effects of UV, proton, and atomic oxygen exposure on coatings and on assembled solar cells as related to the implemented deposition processes and material compositions were small. The UVR/AR coatings protected flexible polymer substrate materials that are intended for future flexible multijunction cell arrays to be deployed from rolls. Progress was made toward developing stable and protective coatings for extended space-mission applications. Test results are presented. PMID:24514237

  12. A High-Transmission, Multiple Antireflective Surface Inspired from Bilayer 3D Ultrafine Hierarchical Structures in Butterfly Wing Scales.

    PubMed

    Han, Zhiwu; Mu, Zhengzhi; Li, Bo; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

    2016-02-10

    A high-transmission, multiple antireflective surface inspired by bilayer 3D ultrafine hierarchical structures in butterfly wing scales is fabricated on a glass substrate using wet chemical biomimetic fabrication. Interestingly, the biomimetic antireflective surface exhibits excellent antireflective properties and high transmission, which provides better characteristics than the butterfly wings and can significantly reduce reflection without losing transparency. These findings offer a new path for generating nanostructured antireflectors with high transmission properties. PMID:26687864

  13. Development of high-throughput silicon lens and grism with moth-eye anti-reflection structure

    NASA Astrophysics Data System (ADS)

    Kamizuka, Takafumi; Miyata, Takashi; Sako, Shigeyuki; Imada, Hiroaki; Ohsawa, Ryou; Asano, Kentaro; Uchiyama, Mizuho; Okada, Kazushi; Uchiyama, Masahito; Wada, Takehiko; Nakagawa, Takao; Nakamura, Tomohiko; Sakon, Itsuki; Onaka, Takashi

    2014-07-01

    Anti-reflection (AR) is very important for high-throughput optical elements. The durability against cooling is required for the AR structure in the cryogenic optics used for mid-infrared astronomical instruments. Moth-eye structure is a promising AR technique strong against cooling. The silicon lens and grism with the moth-eye structure are being developed to make high-throughput elements for long-wavelength mid-infrared instruments. A double-sided moth-eye plano-convex lens (Effective diameter: 33 mm, Focal length: 188 mm) was fabricated. By the transmittance measurement, it was confirmed that its total throughput is 1.7+/- 0.1 times higher than bare silicon lenses in a wide wavelength range of 20{45 μm. It suggests that the lens can achieve 83+/-5% throughput in the cryogenic temperature. It was also confirmed that the moth-eye processing on the lens does not modify the focal length. As for the grism, the homogeneous moth-eye processing on blaze pattern was realized by employing spray coating for the resist coating in EB lithography. The silicon grism with good surface roughness was also developed. The required techniques for completing moth-eye grisms have been established.

  14. Broadband antireflection sub-wavelength structure of InGaP/InGaAs/Ge triple junction solar cell with composition-graded SiNx

    NASA Astrophysics Data System (ADS)

    Chung, Chen-Chen; Lo, Hsiao-Chieh; Lin, Yen-Ku; Yu, Hung-Wei; Tinh Tran, Binh; Lin, Kung-Liang; Chen, Yung Chang; Quan, Nguyen-Hong; Chang, Edward Yi; Tseng, Yuan-Chieh

    2015-05-01

    This work reports a fabrication strategy to improve the antireflective ability of a InGaP/GaAs/Ge triple-junction solar cell, by combining a nano-templating technique and a chemical-synthesis approach. SiH4 and N2 were used as ammonia-free reaction gases in a plasma-enhanced chemical vapor deposition (PECVD) to prepare Si3N4 as an original antireflective coating (ARC) layer with better chemical stability. Composition-graded SiNx was successfully integrated with sub-wavelength structure by modulating SiH4/N2 ratio during PECVD deposition, and followed by a controllable gold-nanoparticle masking technique on top of the solar cell. Finite-difference time-domain solution was employed to simulate and optimize the aspect-ratio of the ARC, under the condition of variable refractive index over a broad wavelength window, and followed by the masking technique to obtain the desired ARC dimension. This enabled a low light reflectance (<10%) over a broad spectral bandwidth (300-1800 nm) for the solar cell with excellent stability, because of the triple advantages of structural optimization, better chemical stability and graded refractive index of the ARC. The solar cell’s performance was tested and showed great competitiveness to those of forefront studies, suggesting the feasibility of the proposed technology.

  15. Antireflection properties and solar cell application of silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Huihui, Yue; Rui, Jia; Chen, Chen; Wuchang, Ding; Deqi, Wu; Xinyu, Liu

    2011-08-01

    Silicon nanowire arrays (SiNWAs) are fabricated on polished pyramids of textured Si using an aqueous chemical etching method. The silicon nanowires themselves or hybrid structures of nanowires and pyramids both show strong anti-reflectance abilities in the wavelength region of 300-1000 nm, and reflectances of 2.52% and less than 8% are achieved, respectively. A 12.45% SiNWAs-textured solar cell (SC) with a short circuit current of 34.82 mA/cm2 and open circuit voltage (Voc) of 594 mV was fabricated on 125 × 125 mm2 Si using a conventional process including metal grid printing. It is revealed that passivation is essential for hybrid structure textured SCs, and Voc can be enlarged by 28.6% from 420 V to 560 mV after the passivation layer is deposited. The loss mechanism of SiNWA SC was investigated in detail by systematic comparison of the basic parameters and external quantum efficiency (EQE)of samples with different fabrication processes. It is proved that surface passivation and fabrication of a metal grid are critical for high efficiency SiNWA SC, and the performance of SiNWA SC could be improved when fabricated on a substrate with an initial PN junction.

  16. Analysis and design of transmittance for an antireflective surface microstructure.

    PubMed

    Jing, Xufeng; Ma, Jianyong; Liu, Shijie; Jin, Yunxia; He, Hongbo; Shao, Jianda; Fan, Zhengxiu

    2009-08-31

    In order to easily analyze and design the transmittance characteristics of an antireflective surface called the 'moth-eye structure', the validity of both scalar diffraction theory and effective medium theory is quantitatively evaluated by a comparison of diffraction efficiencies predicted from both simplified theories to exact results calculated by a rigorous electromagnetic theory. The effect of surface microstructure parameters including the normalized period and the normalized depth has been determined at normal incidence. It is found that, in general, when the normalized period is more than four wavelengths of the incident light the scalar diffraction theory is useful within the error of 5%. Besides, the effective medium theory is accurate for evaluating the diffraction efficiency within the error of less than 1% when the higher order diffraction waves other than zero order wave is not to propagate. In addition, the limitation of scalar diffraction method and effective refractive index method is dependent on not only the normalized period of surface profile but also the normalized groove depth. PMID:19724612

  17. Design and optimization of dielectric optical coatings for GaN based high bright LEDs

    NASA Astrophysics Data System (ADS)

    Wang, Xiaodong; Li, Yan; Yang, Hua; Yi, Xiaoyan; Wang, Liangchen; Wang, Guohong; Yang, Fuhua; Li, Jinmin

    2008-03-01

    Different types of dielectric optical coatings for GaN based high bright LEDs were designed and discussed. The optical coatings included the anti-reflection (AR) coating, high-reflection (HR) coating, and omni-directional high reflection coating. Main materials for the optical coatings were dielectric materials such as SiO II, Ta IIO 5 and Al IIO 3, which were different from the metallic reflector such as Ag usually used now. For the application of anti-reflection coating in GaN LEDs, it was introduced into the design of transparent electrodes with transparent materials such as ITO to form combined transparent electrodes. With the design of P, N transparent electrodes using the AR coating and ITO for GaN LEDs, the extraction efficiency was improved by about 15% experimentally. For the dielectric high-reflection coating, it has higher reflectivity and lower absorption than the metal reflector, and it was supposed to improve the extraction efficiency obviously. While the dielectric omni-directional reflection coating using dielectric materials was also designed and discussed in this article, since which was anticipated to improve the extraction efficiency furthermore. Using SiO II and Ta IIO 5, the average reflectivity of a design of all dielectric omni-directional high reflection coating on the sapphire surface was over 94%.

  18. Superior broadband antireflection from buried Mie resonator arrays for high-efficiency photovoltaics.

    PubMed

    Zhong, Sihua; Zeng, Yang; Huang, Zengguang; Shen, Wenzhong

    2015-01-01

    Establishing reliable and efficient antireflection structures is of crucial importance for realizing high-performance optoelectronic devices such as solar cells. In this study, we provide a design guideline for buried Mie resonator arrays, which is composed of silicon nanostructures atop a silicon substrate and buried by a dielectric film, to attain a superior antireflection effect over a broadband spectral range by gaining entirely new discoveries of their antireflection behaviors. We find that the buried Mie resonator arrays mainly play a role as a transparent antireflection structure and their antireflection effect is insensitive to the nanostructure height when higher than 150 nm, which are of prominent significance for photovoltaic applications in the reduction of photoexcited carrier recombination. We further optimally combine the buried Mie resonator arrays with micron-scale textures to maximize the utilization of photons, and thus have successfully achieved an independently certified efficiency of 18.47% for the nanostructured silicon solar cells on a large-size wafer (156 mm × 156 mm). PMID:25746848

  19. Apparatus and method of manufacture for depositing a composite anti-reflection layer on a silicon surface

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata (Inventor)

    2012-01-01

    An apparatus and associated method are provided. A first silicon layer having at least one of an associated passivation layer and barrier is included. Also included is a composite anti-reflection layer including a stack of layers each with a different thickness and refractive index. Such composite anti-reflection layer is disposed adjacent to the first silicon layer.

  20. Biomimetic compound eye with a high numerical aperture and anti-reflective nanostructures on curved surfaces.

    PubMed

    Wang, T; Yu, W; Li, C; Zhang, H; Xu, Z; Lu, Z; Sun, Q

    2012-06-15

    Biomimetic compound eyes with a high numerical aperture on a curved surface were successfully fabricated by intelligent integration of traditional top-down and bottom-up micro- and nanofabrication methods together. In addition, the new hybrid micro- and nanofabrication method allows us to fabricate the antireflective nanostructures on each ommatidium to increase its vision sensitivity by improving the light transmission. The fabricated compound eye was optically characterized and was shown to have a numerical aperture of 0.77 for each ommatidium. Furthermore, it is shown that the transmission of the compound eye can be improved by 2.3% for the wavelength of 632.8 nm and a clearer image can be formed by the fabricated compound eye with antireflective nanostructures compared with that without antireflective nanostructures. In addition, the developed hybrid manufacturing method can be adapted to the fabrication of other complex micro- and nanodevices for photonics or other research areas. PMID:22739920

  1. Scattering analysis for random antireflective structures on fused silica in the ultraviolet.

    PubMed

    Zhao, Jiaoling; Qi, Hongji; Wang, Hu; He, Hongbo; Zhang, Weili

    2015-11-15

    Random antireflective structures are fabricated on fused silica by the thermal dewetting process and reactive ion etching, which shows a broadband antireflective effect over the whole visible wavelength. However, the transmittance in the ultraviolet is limited by the scattering from the etched structures. A graded refractive index model ignoring the scattering in the visible range is applied to extract the etched profile. Then the Lubachevsky-Stillinger algorithm is used to reconstruct the random antireflective structures with the extracted profile. Bidirectional scattering distribution for the reconstructed structures is simulated with the finite-difference time-domain method, which indicates the importance of transmissive scattering the scattering directivity. The scattering directivity is explained well with an effective grating model. The period of the effective grating can guide the prepared technique in the ultraviolet. PMID:26565826

  2. Advanced antireflective nanostructures etched down from nanosilver colloid-transformed island mask

    NASA Astrophysics Data System (ADS)

    Park, Seong-Je; Kim, Chul-Hyun; Lee, Ji-Hye; Jeong, Jun-Ho; Lee, Eung-Sug; Choi, Jun-Hyuk

    2012-11-01

    Advanced fabrication methods for antireflective nanostructures are presented via the formation of thermally grown nanosilver islands from continuously deposited colloidal multilayers, followed by a multi-step reactive ion etch (RIE) with optimized gas mixture rate. This process allows the formation of a random array of nanostructures of diameter 150 nm or less and height greater than 200 nm. The reflectance falls to around 0.7% in the visible region, with reasonably enhanced broadband stability and reduced incidence angle dependence. The tunability of antireflection was investigated with respect to several parameters associated with the nanosilver etch mask fabrication and RIE conditions.

  3. Hollow carbon spheres in microwaves: Bio inspired absorbing coating

    NASA Astrophysics Data System (ADS)

    Bychanok, D.; Li, S.; Sanchez-Sanchez, A.; Gorokhov, G.; Kuzhir, P.; Ogrin, F. Y.; Pasc, A.; Ballweg, T.; Mandel, K.; Szczurek, A.; Fierro, V.; Celzard, A.

    2016-01-01

    The electromagnetic response of a heterostructure based on a monolayer of hollow glassy carbon spheres packed in 2D was experimentally surveyed with respect to its response to microwaves, namely, the Ka-band (26-37 GHz) frequency range. Such an ordered monolayer of spheres mimics the well-known "moth-eye"-like coating structures, which are widely used for designing anti-reflective surfaces, and was modelled with the long-wave approximation. Based on the experimental and modelling results, we demonstrate that carbon hollow spheres may be used for building an extremely lightweight, almost perfectly absorbing, coating for Ka-band applications.

  4. Structural and optical properties of ITO/TiO2 anti-reflective films for solar cell applications.

    PubMed

    Ali, Khuram; Khan, Sohail A; Jafri, Mohd Zubir Mat

    2014-01-01

    Indium tin oxide (ITO) and titanium dioxide (TiO2) anti-reflective coatings (ARCs) were deposited on a (100) P-type monocrystalline Si substrate by a radio-frequency (RF) magnetron sputtering. Polycrystalline ITO and anatase TiO2 films were obtained at room temperature (RT). The thickness of ITO (60 to 64 nm) and TiO2 (55 to 60 nm) films was optimized, considering the optical response in the 400- to 1,000-nm wavelength range. The deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). The XRD analysis showed preferential orientation along (211) and (222) for ITO and (200) and (211) for TiO2 films. The XRD analysis showed that crystalline ITO/TiO2 films could be formed at RT. The crystallite strain measurements showed compressive strain for ITO and TiO2 films. The measured average optical reflectance was about 12% and 10% for the ITO and TiO2 ARCs, respectively. PMID:24721986

  5. Study of faceted Au nanoparticle capped ZnO nanowires: antireflection, surface enhanced Raman spectroscopy and photoluminescence aspects

    NASA Astrophysics Data System (ADS)

    Ghosh, A.; Juluri, R. R.; Guha, P.; Sathyavathi, R.; Dash, Ajit; Jena, B. K.; Satyam, P. V.

    2015-02-01

    We report a single step growth process of faceted Au nanoparticles (NPs) on highly c-axis oriented ZnO nanowires (NWs) and report that a system with a lower antireflection coefficient also showed higher surface enhanced Raman spectroscopy (SERS) enhanced factors. Well-dispersed Au NPs are grown on silicon substrate using a thin film-in-air-annealing method (using 1 nm and 5 nm thick Au films on silicon and subsequent annealing in air at 800 °C) wherein enhanced oxide growth at the Au-Si interface was used to inhibit inter-diffusion to avoid Au-Si alloy formation (Au/SiOx/Si). These substrates are used to grow aligned ZnO NWs using a high temperature (≈900 °C) chemical vapour deposition method. Depending on the size and areal density of initial catalytic Au NPs, the resultant photoluminescence, reflectance characteristics, and effectiveness as SERS substrates of the faceted Au NP capped ZnO NWs coatings are systematically studied. The highly oriented and faceted Au NPs on ZnO NWs have been used as free standing SERS substrates to detect sub-micro molar crystal violet molecules with an analytical enhancement factor (AEF) of ≥104 and with high repeatability. The substrate with high-density Au-ZnO heterostructures (5 nm Au case) found to have larger AEF, very low reflectance (≈0.75%) and more green emission.

  6. Self-Assembled Biomimetic Nanostructured Anti-Reflection Coatings for Highly Efficient Crystalline Silicon Solar Cells

    SciTech Connect

    2009-04-01

    This factsheet describes a study that will further develop the structure-property relationship understanding and performance testing of biomimetic nanostructured ARCs produced by a robust templating nanofabrication platform that combines the simplicity and cost benefits of bottom-up self-assembly with the scalability and compatibility of top-down microfabrication.

  7. Two dimensional metallic photonic crystals for light trapping and anti-reflective coatings in thermophotovoltaic applications

    SciTech Connect

    Shemelya, Corey; DeMeo, Dante F.; Vandervelde, Thomas E.

    2014-01-13

    We report the development of a front-side contact design for thermophotovoltaics that utilizes metallic photonic crystals (PhCs). While this front-side grid replacement covers more surface area of the semiconductor, a higher percentage of photons is shown to be converted to usable power in the photodiode. This leads to a 30% increase in the short-circuit current of the gallium antimonide thermophotovoltaic cell.

  8. Evaluation of glass resin coatings for solar cell applications

    NASA Technical Reports Server (NTRS)

    Field, M. B.

    1978-01-01

    Using a variety of non-vacuum deposition techniques coatings were implemented on silicon solar cells and arrays of cells interconnected on Kapton substrates. The coatings provide both antireflection optical matching and environmental protection. Reflectance minima near 2% was achieved at a single wavelength in the visible. Reflectance averaging below 5% across the useful collection range was demonstrated. The coatings and methods of deposition were: (1) Ta2O5 spun, dipped or sprayed; (2) Ta2O5.SiO2 spun, dipped or sprayed; (3) GR908 (SiO2) spun, dipped, or sprayed. Total coating thickness were in the range of 18 microns to 25 microns. The coatings and processes are compatible with single cells or cells mounted on Kapton substrates.

  9. Self-assembled nanolaminate coatings (SV)

    SciTech Connect

    Fan, H.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Aeronautics (LM Aero) are collaborating to develop affordable, self-assembled, nanocomposite coatings and associated fabrication processes that will be tailored to Lockheed Martin product requirements. The purpose of this project is to develop a family of self-assembled coatings with properties tailored to specific performance requirements, such as antireflective (AR) optics, using Sandia-developed self-assembled techniques. The project met its objectives by development of a simple and economic self-assembly processes to fabricate multifunctional coatings. Specifically, materials, functionalization methods, and associated coating processes for single layer and multiple layers coatings have been developed to accomplish high reflective coatings, hydrophobic coatings, and anti-reflective coatings. Associated modeling and simulations have been developed to guide the coating designs for optimum optical performance. The accomplishments result in significant advantages of reduced costs, increased manufacturing freedom/producibility, improved logistics, and the incorporation of new technology solutions not possible with conventional technologies. These self-assembled coatings with tailored properties will significantly address LMC's needs and give LMC a significant competitive lead in new engineered materials. This work complements SNL's LDRD and BES programs aimed at developing multifunctional nanomaterials for microelectronics and optics as well as structure/property investigations of self-assembled nanomaterials. In addition, this project will provide SNL with new opportunities to develop and apply self-assembled nanocomposite optical coatings for use in the wavelength ranges of 3-5 and 8-12 micrometers, ranges of vital importance to military-based sensors and weapons. The SANC technologies will be applied to multiple programs within the LM Company including the F-35, F-22, ADP (Future Strike Bomber, UAV, UCAV

  10. Diffusion of dopant from optical coating and single step formation of pn junction in silicon solar cell and coating thereon

    SciTech Connect

    Yoldas, B. E.; Yoldas, L. A.

    1981-02-17

    The pn juncture in a silicon chip and an oxide coating on its surface are simultaneously formed from clear solution derived from titanium alkoxides, water, alcohol, a suitable acid, and a P or N dopant compound by partial hydrolysis and polymerization. The solution is applied to the surface of a silicon chip. The chip is then heated which converts the solution to a solid oxide coating which meets the antireflective optical film requirements and induces the migration of the dopants into the chip, forming a pn junction in the chip. The method also provides deep and uniform junction formation or diffusion without resulting in excessive carrier concentration.

  11. Top-flat and top-patterned cone gratings for mid-infrared antireflective properties

    NASA Astrophysics Data System (ADS)

    Brückner, Jean-Baptiste; Le Rouzo, Judikaël.; Escoubas, Ludovic; Flory, François; Simon, Jean-Jacques; Berginc, Gérard

    2013-03-01

    Achieving a broadband antireflection property from material surfaces is one of the highest priorities for those who want to improve the efficiency of solar cells or the sensitivity of photo-detectors. To lower the reflectance of a surface, we have decided to study the optical response of a top-flat cone shaped silicon grating, based on previous work exploring pyramid gratings. Through rigorous numerical methods, such as Finite Different Time Domain or Rigorous Coupled-Wave Analysis, we then designed several structures theoretically demonstrating an antireflective character within the middle infrared region. From the opto-geometrical parameters such as period, depth and shape of the pattern determined by numerical analysis, these structures have been fabricated using controlled slope plasma etching processes. Afterwards, optical characterizations of several samples were carried out. The reflectance of the grating in the near and middle infrared domains has been measured by Fourier Transform Infrared spectrometry and a comparison with numerical analysis has been made. As expected, those structures offer a fair antireflective character in the region of interest. Further numerical investigations led to the fact that patterning the top of the cone could enlarge the antireflective domain to the visible region. Thus, as with the simple cone grating, a comparison of the numerical analysis with the experimental measurements is made. Finally, diffracted orders are studied and compared between both structures. Those orders are critical and must be limited as one wants to avoid crosstalk phenomena in imaging systems.

  12. Use of antireflection layers to avoid ghost plating on Ni/Cu plated crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Jeong, Myeong Sang; Choi, Sung Jin; Chang, Hyo Sik; In Lee, Jeong; Kang, Min Gu; Kim, Donghwan; Song, Hee-eun

    2016-03-01

    Screen printing is a method commonly used for making electrodes for crystalline silicon solar cells. Although the screen-printing method is fast and easy, screen-printed electrodes have a porous structure, high contact resistance, and low aspect ratio. On the other hand, plated electrodes have low contact resistance and narrow electrode width. Therefore, the plating method could be substituted for the screen-printing method in crystalline silicon solar cells. During the plating process, ghost plating can appear at the surface when the quality of the passivation layer is poor, causing an increase in the recombination rate. In this paper, light-induced plating was applied to the fabrication of electrodes, and various passivation layers were investigated to remove ghost plating in crystalline silicon solar cells. These included, (1) SiNx deposited by plasma-enhanced chemical vapor deposition (PECVD), (2) a double SiNx layer formed by PECVD, (3) a double layer with thermal silicon oxide and SiNx deposited by PECVD, and (4) a double layer comprising SiNx and SiOx formed by PECVD. For the plated solar cells, a laser was used to remove various antireflection coating (ARC) layers and phosphoric acid was spin-coated onto the doped silicon wafer prior to laser ablation. Also, a screen-printed solar cell was fabricated to compare plated solar cells with screen-printed solar cells. As a result, we found that a thermal SiO2/PECVD SiNx layer showed the lowest pinhole density and its wet vapor transmission rate was characterized. The solar cell with the thermal SiO2/PECVD SiNx layer showed the lowest J02 value, as well as improved Voc and Jsc.

  13. Application of germanium carbide in durable multilayer IR coatings

    NASA Astrophysics Data System (ADS)

    Kelly, Chris J.; Orr, James S.; Gordon, H.; Traub, Leonard T.; Lettington, Alan H.

    1990-08-01

    Infrared transparent amorphous hydrogenated alloys of germanium and carbon (germanium carbide) have been deposited by plasma assisted chemical vapour deposition (PACVD) using germane (GeH4 ) and butane (C 4Hid as the feedstocks and by reactive sputtering of germanium with a CH1g-Ar plasma. The effects of varying various deposition conditions have been assessed on a number of coating properties . Germanium Carbide has good environmental durability and can be deposited in thick layers. Using PACVD it can be deposited with any refractive index in the range 2 to 4 while the sputtering process is limited to indices in the range 3 to 4 . One advantage of the sputtering process is the high deposition rates achievable which can be up to '-lOum/h compared with lum/h for the PACVD process. When used in conjunction with "diamond-like" carbon (a-'C:H) , germanium carbide offers the prospect of rnultilayer antireflection coatings for 8 to 12 urn optics with durabilities which hitherto have been impossible to achieve. Antireflection coatings for zinc sulphide windows which are subject to hostile environmental conditions have been investigated and the performance of the coatings is presented. The factors affecting the practical realisation of these coatings on a production scale are discussed.

  14. Improvement and characterization of high-reflective and anti-reflective nanostructured mirrors by ion beam assisted deposition for 944 nm high power diode laser

    NASA Astrophysics Data System (ADS)

    Ghadimi-Mahani, A.; Farsad, E.; Goodarzi, A.; Tahamtan, S.; Abbasi, S. P.; Zabihi, M. S.

    2015-11-01

    Single-layer and multi-layer coatings were applied on the surface of diode laser facets as mirrors. This thin film mirrors were designed, deposited, optimized and characterized. The effects of mirrors on facet passivation and optical properties of InGaAs/AlGaAs/GaAs diode lasers were investigated. High-Reflective (HR) and Anti-Reflective (AR) mirrors comprising of four double-layers of Al2O3/Si and a single layer of Al2O3, respectively, were designed and optimized by Macleod software for 944 nm diode lasers. Optimization of Argon flow rate was studied through Alumina thin film deposition by Ion Beam Assisted Deposition (IBAD) for mirror improvement. The nanostructured HR and AR mirrors were deposited on the front and back facet of the laser respectively, by IBAD system under optimum condition. Atomic Force Microscope (AFM), Vis-IR Spectrophotometer, Field Emission Scanning Electron Microscopy (FESEM) and laser characterization Test (P-I) were used to characterize various properties of mirrors and lasers. AFM images show mirror's root mean square roughness is nearly 1 nm. The Spectrophotometer results of the front facet transmission and the back facet reflection are in good agreement with the simulation results. Optical output power (P) versus driving current (I) characteristics, measured before and after coating the facet, revealed a significant output power enhancement due to optimized AR and HR optical coatings on facets.

  15. Vacuum-deposited optical coatings experiment (A0138-4)

    NASA Technical Reports Server (NTRS)

    Malherbe, A.

    1984-01-01

    The stability of various vacuum deposited optical coatings exposed to the space environment were analyzed. A wide range of optical components manufactured by vacuum deposition, such as metallic and multidielectric reflective coatings in the UV range, metal dielectric interference filtes in the UV and IR ranges, narrow-bandpass filters int he near-UV and visible ranges, selective metallic mirrors in the range from 1500 to 2500 A. antireflective and reflective IR coatings, beam splitters in the visible and IR ranges, and optical surface reflection (OSR) coatings were developed. Many of these components were incorporated into scientific and technical experiments flown on balloons and rockets as well as on Symphonie, Meteosate, OTS, D2-B, TIROS n, and others. It appears that these components operate successfully in flight.

  16. Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Wang, Wenjun; Jiang, Gedong; Mei, Xuesong

    2016-06-01

    A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet-visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the

  17. Transparent conductive coatings

    NASA Technical Reports Server (NTRS)

    Ashok, S.

    1983-01-01

    Thin film transparent conductors are discussed. Materials with electrical conductivity and optical transparency are highly desirable in many optoelectronic applications including photovoltaics. Certain binary oxide semiconductors such as tin oxide (SnO2) and indium oxide (In2O3) offer much better performance tradeoff in optoelectronics as well as better mechanical and chemical stability than thin semitransparent films. These thin-film transparent conductors (TC) are essentially wide-bandgap degenerate semiconductors - invariably n-type - and hence are transparent to sub-bandgap (visible) radiation while affording high electrical conductivity due to the large free electron concentration. The principal performance characteristics of TC's are, of course, electrical conductivity and optical transmission. The TC's have a refractive index of around 2.0 and hence act as very efficient antireflection coatings. For using TC's in surface barrier solar cells, the photovoltaic barrier is of utmost importance and so the work function or electron affinity of the TC is also a very important material parameter. Fabrication processes are discussed.

  18. Solution-phase synthesis of single-crystal Cu3Si nanowire arrays on diverse substrates with dual functions as high-performance field emitters and efficient anti-reflective layers

    NASA Astrophysics Data System (ADS)

    Yuan, Fang-Wei; Wang, Chiu-Yen; Li, Guo-An; Chang, Shu-Hao; Chu, Li-Wei; Chen, Lih-Juann; Tuan, Hsing-Yu

    2013-09-01

    There is strong and growing interest in applying metal silicide nanowires as building blocks for a new class of silicide-based applications, including spintronics, nano-scale interconnects, thermoelectronics, and anti-reflective coating materials. Solution-phase environments provide versatile materials chemistry as well as significantly lower production costs compared to gas-phase synthesis. However, solution-phase synthesis of silicide nanowires remains challenging due to the lack of fundamental understanding of silicidation reactions. In this study, single-crystalline Cu3Si nanowire arrays were synthesized in an organic solvent. Self-catalyzed, dense single-crystalline Cu3Si nanowire arrays were synthesized by thermal decomposition of monophenylsilane in the presence of copper films or copper substrates at 420 to 475 °C and 10.3 MPa in supercritical benzene. The solution-grown Cu3Si nanowire arrays serve dual functions as field emitters and anti-reflective layers, which are reported on copper silicide materials for the first time. Cu3Si nanowires exhibit superior field-emission properties, with a turn-on-voltage as low as 1.16 V μm-1, an emission current density of 8 mA cm-2 at 4.9 V μm-1, and a field enhancement factor (β) of 1500. Cu3Si nanowire arrays appear black with optical absorption less than 5% between 400 and 800 nm with minimal reflectance, serving as highly efficient anti-reflective layers. Moreover, the Cu3Si nanowires could be grown on either rigid or flexible substrates (PI). This study shows that solution-phase silicide reactions are adaptable for high-quality silicide nanowire growth and demonstrates their promise towards fabrication of metal silicide-based devices.There is strong and growing interest in applying metal silicide nanowires as building blocks for a new class of silicide-based applications, including spintronics, nano-scale interconnects, thermoelectronics, and anti-reflective coating materials. Solution-phase environments

  19. Geometric dependence of antireflective nanocone arrays towards ultrathin crystalline silicon solar cells.

    PubMed

    Zhou, Keya; Li, Xiaopeng; Liu, Shutian; Lee, Jung-Ho

    2014-10-17

    The antireflective characteristics of Si nanocone (NC) arrays were estimated using a theory devised for an inhomogeneous antireflection layer, and further verified by the Fourier modal method (FMM). Considering a better impedance matching from air to Si, a minimum depth of 400 nm is essentially required. Although Si NC arrays have usually been suggested to be at a base diameter of ∼300 nm for infinitely thick Si wafers, as wafers become thinner than 50 μm, the optimal base diameter of the NCs is suggested to be ∼500 nm so as to excite more resonant modes. Our simulation work indicates that geometrical parameters such as the top diameter and filling ratio of the NCs are much more sensitive in terms of optimizing the optical performance on ultrathin (∼5 μm) wafers, suggesting the need for strict control of the surface morphology in the nanostructure fabrication process. PMID:25248800

  20. Lithography-free wide-angle antireflective self-cleaning silicon nanocones.

    PubMed

    Gouda, A M; Elsayed, M Y; Khalifa, A E; Ismail, Y; Swillam, M A

    2016-08-01

    Low-cost, wideband, and wide-angle antireflective layers are of prime importance to photovoltaic and other optoelectronic applications. We report a novel fabrication methodology of random textured silicon nanocones (SiNCs) array through metal-assisted chemical etching combined with oxidation. The optical properties of the fabricated structure are studied theoretically and experimentally. The random textured SiNCs array showed very promising broadband antireflective properties through the entire visible wavelength range at different incident angles up to ±60°. In addition, the nanostructures inherently could become self-cleaning due to the high contact angle. This random cheap textured SiNCs array increases the absorption efficiency of photodetectors and reduces its cost. PMID:27472622

  1. Black metal thin films by deposition on dielectric antireflective moth-eye nanostructures

    PubMed Central

    Christiansen, Alexander B.; Caringal, Gideon P.; Clausen, Jeppe S.; Grajower, Meir; Taha, Hesham; Levy, Uriel; Asger Mortensen, N.; Kristensen, Anders

    2015-01-01

    Although metals are commonly shiny and highly reflective, we here show that thin metal films appear black when deposited on a dielectric with antireflective moth-eye nanostructures. The nanostructures were tapered and close-packed, with heights in the range 300-600 nm, and a lateral, spatial frequency in the range 5–7 μm−1. A reflectance in the visible spectrum as low as 6%, and an absorbance of 90% was observed for an Al film of 100 nm thickness. Corresponding experiments on a planar film yielded 80% reflectance and 20% absorbance. The observed absorbance enhancement is attributed to a gradient effect causing the metal film to be antireflective, analogous to the mechanism in dielectrics and semiconductors. We find that the investigated nanostructures have too large spatial frequency to facilitate efficient coupling to the otherwise non-radiating surface plasmons. Applications for decoration and displays are discussed. PMID:26035526

  2. The fabrication of subwavelength anti-reflective nanostructures using a bio-template

    NASA Astrophysics Data System (ADS)

    Xie, Guoyong; Zhang, Guoming; Lin, Feng; Zhang, Jin; Liu, Zhongfan; Mu, Shichen

    2008-03-01

    This paper describes a paradigm, a simple, low-cost and conventional approach to the fabrication of large-area subwavelength anti-reflective nanostructures on films directly with a bio-template. Specifically, the nano-nipple arrays on the surface of cicada wings have been precisely replicated to a PMMA (polymethyl methacrylate) film with high reproducibility by a technique of replica molding, which mainly involves two processes: one is that a negative Au mold is prepared directly from the bio-template of the cicada wing by thermal deposition; the other is that the Au mold is used to obtain the replica of the nanostructures on the original cicada wing by casting polymer. The reflectance spectra measurement shows that the replicated PMMA film can considerably reduce reflectivity at its surface over a large wavelength range from 250 to 800 nm, indicating that the anti-reflective property has also been inherited by the PMMA film.

  3. Periodically Aligned Si Nanopillar Arrays as Efficient Antireflection Layers for Solar Cell Applications

    PubMed Central

    2010-01-01

    Periodically aligned Si nanopillar (PASiNP) arrays were fabricated on Si substrate via a silver-catalyzed chemical etching process using the diameter-reduced polystyrene spheres as mask. The typical sub-wavelength structure of PASiNP arrays had excellent antireflection property with a low reflection loss of 2.84% for incident light within the wavelength range of 200–1,000 nm. The solar cell incorporated with the PASiNP arrays exhibited a power conversion efficiency (PCE) of ~9.24% with a short circuit current density (JSC) of ~29.5 mA/cm2 without using any extra surface passivation technique. The high PCE of PASiNP array-based solar cell was attributed to the excellent antireflection property of the special periodical Si nanostructure. PMID:21124636

  4. Wide angle and broadband antireflection properties for a silicon nanotip array

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Fan; Jen, Yi-Jun; Chen, Kuei-Hsien; Chen, Li-Chyong

    2008-08-01

    Biomimetic structures provided important clues for nano-synthesis in pursuit of enhanced performances. Here, we report a wide angle and broadband antireflection is observed on a 6-inch silicon nanotip array (SiNTs) substrate fabricated using a single step electron cyclotron resonance plasma etching technique. This subwavelength structure consists of the SiNTs with apex and bottom diameter of ~5 nm and ~200 nm, respectively, length of ~1600 nm and density of 109/cm2. This aperiodic array of SiNTs with geometry designed in the sub-wavelength level to demonstrate a low hemispherical reflectance of < 1% in the ultraviolet to infrared region. The antireflection property holds good for a wide angle of incidence and both, s and p, forms of polarizations of light. The effective refractive index distribution related to the structure of SiNTs is built. The equivalent three-layered thin films with gradient refractive index can be applied in interpretation of the low reflection phenomenon. The equivalent admittance of the system is shown to be near that of air even the wavelength is varied from 400 nm to 800 nm (or angle of incidence is varied from 25 to 70 degree). The configuration to have broadband and wide-angle antireflection is different from the previous design because the equivalent rare film adjacent to air in our case is much thinner than the requirement proposed by J. A. Dobrowolski. This near ideal antireflection property suggests enhanced performances in renewable energy, and electro-optical devices in defense applications.

  5. Fabrication of CuO-based antireflection structures using self-arranged submicron SiO2 spheres for thermoelectric solar generation

    NASA Astrophysics Data System (ADS)

    Kondo, Tasuku; Mizoshiri, Mizue; Mikami, Masashi; Itou, Yoshitaka; Sakurai, Junpei; Hata, Seiichi

    2016-06-01

    We fabricated antireflection structures (ARSs) on the hot side of a thermoelectric generator (TEG) to absorb near-infrared (NIR) solar light with low reflective energy loss. First, the ARSs, composed of a CuO thin-film coated hemisphere array were designed using rigorous coupled wave analysis. Reflective loss was reduced to 6.7% at a grating period of 200 nm, as determined by simulation. Then, the ARSs were fabricated on a glass substrate using self-arranged submicron SiO2 spheres, following the coating of a CuO thin film. Finally, the effect of the ARSs on NIR solar light generation was investigated by evaluating the generation properties of the TEG with the ARSs on the hot side. In comparison with the TEG with the CuO flat thin film on the hot side, the ARSs increased the temperature difference between the hot and cold sides by approximately 1.4 times. The CuO-based ARSs absorbed NIR solar light effectively.

  6. Both antireflection and superhydrophobicity structures achieved by direct laser interference nanomanufacturing

    SciTech Connect

    Wang, Dapeng; Wang, Zuobin Maple, Carsten; Zhang, Ziang; Yue, Yong; Li, Dayou; Qiu, Renxi

    2014-06-21

    Inspired by nature, a number of techniques have been developed to fabricate the bionic structures of lotus leaves and moth eyes in order to realize the extraordinary functions of self-cleaning and antireflection. Compared with the existing technologies, we present a straightforward method to fabricate well-defined micro and nano artificial bio-structures in this work. The proposed method of direct laser interference nanomanufacturing (DLIN) takes a significant advantage of high efficiency as only a single technological procedure is needed without pretreatment, mask, and pattern transfer processes. Meanwhile, the corresponding structures show both antireflection and superhydrophobicity properties simultaneously. The developed four-beam nanosecond laser interference system configuring the TE-TE-TE-TE and TE-TE-TE-TM polarization modes was set up to generate periodic micro cone and hole structures with a huge number of nano features on the surface. The theoretical and experimental results have shown that the periodic microcone structure exhibits excellent properties with both a high contact angle (CA = 156.3°) and low omnidirectional reflectance (5.9–15.4%). Thus, DLIN is a novel and promising method suitable for mass production of self-cleaning and antireflection surface structures.

  7. Both antireflection and superhydrophobicity structures achieved by direct laser interference nanomanufacturing

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Wang, Zuobin; Zhang, Ziang; Yue, Yong; Li, Dayou; Qiu, Renxi; Maple, Carsten

    2014-06-01

    Inspired by nature, a number of techniques have been developed to fabricate the bionic structures of lotus leaves and moth eyes in order to realize the extraordinary functions of self-cleaning and antireflection. Compared with the existing technologies, we present a straightforward method to fabricate well-defined micro and nano artificial bio-structures in this work. The proposed method of direct laser interference nanomanufacturing (DLIN) takes a significant advantage of high efficiency as only a single technological procedure is needed without pretreatment, mask, and pattern transfer processes. Meanwhile, the corresponding structures show both antireflection and superhydrophobicity properties simultaneously. The developed four-beam nanosecond laser interference system configuring the TE-TE-TE-TE and TE-TE-TE-TM polarization modes was set up to generate periodic micro cone and hole structures with a huge number of nano features on the surface. The theoretical and experimental results have shown that the periodic microcone structure exhibits excellent properties with both a high contact angle (CA = 156.3°) and low omnidirectional reflectance (5.9-15.4%). Thus, DLIN is a novel and promising method suitable for mass production of self-cleaning and antireflection surface structures.

  8. Nanoporosity-induced superhydrophobicity and large antireflection in InSb

    NASA Astrophysics Data System (ADS)

    Datta, Debi Prasad; Som, Tapobrata

    2016-05-01

    A porous nanostructure evolves in InSb due to keV ion implantation which leads to superhydrophobic and large antireflective property, indicating a single-step facile fabrication to introduce both functionalities. In particular, it is observed that the contact angle of a water droplet on the nanoporous InSb surface exceeds 150°, revealing the transition to a superhydrophobic surface. Correlation between the contact angle and the porous nanostructures is qualitatively understood in light of the Cassie-Baxter model. It is found that a decrease in the fraction of solid surface wetted by the water droplet and a corresponding increase in the air-water interface fraction lead to the enhancement in the hydrophobicity. We further observe that the large broadband antireflection (in the range of 200-800 nm) is also correlated to the nanoporous structure, arising out of a large reduction in the refractive index due to its increasing porosity. Such a surface with the combination of superhydrophobicity and large antireflection can be very useful for applications of InSb nanostructures in electronic, photonic devices, or infrared detectors.

  9. UV-black rutile TiO{sub 2}: An antireflective photocatalytic nanostructure

    SciTech Connect

    Sanz, Ruy Zimbone, Massimo; Buccheri, Maria Antonietta; Scuderi, Viviana; Impellizzeri, Giuliana; Privitera, Vittorio; Romano, Lucia; Scuderi, Mario; Nicotra, Giuseppe; Jensen, Jens

    2015-02-21

    This work presents an experimental study on the specific quantitative contributions of antireflective and effective surface areas on the photocatalytic and antibacterial properties of rutile TiO{sub 2} nanospikes. They are studied when continuously distributed over the whole surface and when integrated into well-defined microstructures. The nanospikes were produced following MeV ion beam irradiation of bulk rutile TiO{sub 2} single crystals and subsequent chemical etching. The ion beam irradiation generated embedded isolated crystalline nanoparticles inside an etchable amorphous TiO{sub 2} layer, and nanospikes fixed to the not etchable TiO{sub 2} bulk substrate. The produced nanospikes are shown to resist towards aggressive chemical environments and act as an efficient UV antireflective surface. The photocatalytic activity experiments were performed under the ISO 10678:2010 protocol. The photonic and quantum efficiency are reported for the studied samples. The combined micro- and nanostructured surface triples the photonic efficiency compared to the initial flat surface. Results also revealed that the antireflective effect, due to the nanostructuring, is the dominating factor compared to the increase of surface area, for the observed photocatalytic response. The obtained results may be taken as a general strategy to design and precisely evaluate photoactive nanostructures.

  10. Design principles for morphologies of antireflection patterns for solar absorbing applications.

    PubMed

    Moon, Yoon-Jong; Na, Jin-Young; Kim, Sun-Kyung

    2015-07-01

    Two-dimensional surface texturing is a widespread technology for imparting broadband antireflection, yet its design rules are not completely understood. The dependence of the reflectance spectrum of a periodically patterned glass film on various structural parameters (e.g., pitch, height, shape, and fill factor) has been investigated by means of full-vectorial numerical simulations. An average weighted reflectivity accounting for the AM1.5G solar spectrum (λ=300-1000  nm) was sinusoidally modulated by a rod pattern's height, and was minimized for pitches of 400-600 nm. When a rationally optimized cone pattern was used, the average weighted reflectivity was less than 0.5%, for incident angles of up to 40° off normal. The broadband antireflection of a cone pattern was reproduced well by a graded refractive index film model corresponding to its geometry, with the addition of a diffraction effect resulting from its periodicity. The broadband antireflection ability of optimized cone patterns is not limited to the glass material, but rather is generically applicable to other semiconductor materials, including Si and GaAs. The design rules developed herein represent a key step in the development of light-absorbing devices, such as solar cells. PMID:26193151

  11. Broadband High-Performance Infrared Antireflection Nanowires Facilely Grown on Ultrafast Laser Structured Cu Surface.

    PubMed

    Fan, Peixun; Bai, Benfeng; Long, Jiangyou; Jiang, Dafa; Jin, Guofan; Zhang, Hongjun; Zhong, Minlin

    2015-09-01

    Infrared antireflection is an essential issue in many fields such as thermal imaging, sensors, thermoelectrics, and stealth. However, a limited antireflection capability, narrow effective band, and complexity as well as high cost in implementation represent the main unconquered problems, especially on metal surfaces. By introducing precursor micro/nano structures via ultrafast laser beforehand, we present a novel approach for facile and uniform growth of high-quality oxide semiconductor nanowires on a Cu surface via thermal oxidation. Through the enhanced optical phonon dissipation of the nanowires, assisted by light trapping in the micro structures, ultralow total reflectance of 0.6% is achieved at the infrared wavelength around 17 μm and keeps steadily below 3% over a broad band of 14-18 μm. The precursor structures and the nanowires can be flexibly tuned by controlling the laser processing procedure to achieve desired antireflection performance. The presented approach possesses the advantages of material simplicity, structure reconfigurability, and cost-effectiveness for mass production. It opens a new path to realize unique functions by integrating semiconductor nanowires onto metal surface structures. PMID:26280305

  12. High power laser antireflection subwavelength grating on fused silica by colloidal lithography

    NASA Astrophysics Data System (ADS)

    Ye, Xin; Huang, Jin; Geng, Feng; Liu, Hongjie; Sun, Laixi; Yan, Lianghong; Jiang, Xiaodong; Wu, Weidong; Zheng, Wanguo

    2016-07-01

    In this study we report on an efficient and simple method to fabricate an antireflection subwavelength grating on a fused silica substrate using two-step reactive ion etching with monolayer polystyrene colloidal crystals as masks. We show that the period and spacing of the obtained subwavelength grating were determined by the initial diameter of polystyrene microspheres and the oxygen ion etching duration. The height of pillar arrays can be adjusted by tuning the second-step fluorine ion etching duration. These parameters are proved to be useful in tailoring the antireflection properties of subwavelength grating using a finite-difference time-domain (FDTD) method and effective medium theory. The subwavelength grating exhibits excellent antireflection properties. The near-field distribution of the SWG which is directly patterned into the substrate material is performed by a 3D-FDTD method. It is found that the near-field distribution is strongly dependent on the periodicity of surface structure, which has the potential to promote the ability of anti-laser-induced damage. For 10 ns pulse duration and 1064 nm wavelength, we experimentally determined their laser induced damage threshold to 32 J cm‑2, which is nearly as high as bulk fused silica with 31.5 J cm‑2.

  13. High-contrast top-emitting organic light-emitting diodes with a Ni/ZnS/CuPc/Ni contrast-enhancing stack and a ZnS anti-reflection layer

    NASA Astrophysics Data System (ADS)

    Chen, Shufen; Xie, Jun; Yang, Yang; Chen, Chunyan; Huang, Wei

    2010-09-01

    High-contrast top-emitting organic light-emitting diodes are successfully fabricated using a Ni/ZnS/copper-phthalocyanine (CuPc)/Ni contrast-enhancing stack (CES) and a ZnS anti-reflection (AR) layer. The CES and AR layer that are outside the active region reduce the complexity of the device design although their utilization affects the device electrical performance due to morphological deterioration of the device films. After the thickness optimization of the CES and AR coating, high contrast ratios of 139.4 : 1 and 462.3 : 1 are obtained under on-state luminances of 300 and 1000 cd m-2 and an ambient luminance of 140 lux. The reduced reflectance of ambient illumination is mainly due to the anti-reflection ZnS layer and the strong absorption of ambient illumination by the Ni layers, where the CES structure is beneficial for the absorption of ambient illumination by the interfacial reflection of Ni/ZnS and CuPc/Ni.

  14. High temperature solar selective coatings

    DOEpatents

    Kennedy, Cheryl E

    2014-11-25

    Improved solar collectors (40) comprising glass tubing (42) attached to bellows (44) by airtight seals (56) enclose solar absorber tubes (50) inside an annular evacuated space (54. The exterior surfaces of the solar absorber tubes (50) are coated with improved solar selective coatings {48} which provide higher absorbance, lower emittance and resistance to atmospheric oxidation at elevated temperatures. The coatings are multilayered structures comprising solar absorbent layers (26) applied to the meta surface of the absorber tubes (50), typically stainless steel, topped with antireflective Savers (28) comprising at least two layers 30, 32) of refractory metal or metalloid oxides (such as titania and silica) with substantially differing indices of refraction in adjacent layers. Optionally, at least one layer of a noble metal such as platinum can be included between some of the layers. The absorbent layers cars include cermet materials comprising particles of metal compounds is a matrix, which can contain oxides of refractory metals or metalloids such as silicon. Reflective layers within the coating layers can comprise refractory metal silicides and related compounds characterized by the formulas TiSi. Ti.sub.3SiC.sub.2, TiAlSi, TiAN and similar compounds for Zr and Hf. The titania can be characterized by the formulas TiO.sub.2, Ti.sub.3O.sub.5. TiOx or TiO.sub.xN.sub.1-x with x 0 to 1. The silica can be at least one of SiO.sub.2, SiO.sub.2x or SiO.sub.2xN.sub.1-x with x=0 to 1.

  15. Imprinted moth-eye antireflection patterns on glass substrate

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Hoon; Bae, Byeong-Ju; Han, Kang-Soo; Hong, Eun-Ju; Lee, Heon; Choi, Kyung-Woo

    2009-03-01

    Sub-micron sized, conical shaped moth-eye structure was transferred to thermoplastic polymer film, such as polyvinyl chloride (PVC) using hot embossing process. Since master template was made of polycarbonate, embossing temperature and pressure were carefully maintained to 100°C and 10 atm. Conical shaped moth-eye pattern was reversed to tapered hole pattern on PVC film. Hot embossed PVC film was then used as transparent template for subsequent UV nanoimprint process, in order to form the conical shaped sub-micron moth-eye structure on glass substrate. After thin layer of Si oxide and monolayer of self-assembled, silane based molecules was coated on hot embossed PVC film. UV nanoimprint process was done on the glass substrate using hot embossed PVC film. As a result, the transmittance of glass substrate was increased from 91 to 94% for single side patterned and 96% for both side patterned glass substrate for the spectral range of 350 to 800 nm.

  16. Full device analysis of novel metamaterial coated PN and MIS solar cells using numerical methods

    NASA Astrophysics Data System (ADS)

    Mandel, Isroel; Gollub, Jonah N.; Sarantos, Chris; Pishbin, Nafiseh; Crouse, David T.

    2012-02-01

    In this work we describe how to model the efficiency of solar cells with novel metamaterial coatings optimized for light harvesting. Full device modeling is implemented using optical and electrical simulations. As a proof of concept, we simulate the operation of a metamaterial contact on a first generation monocrystalline silicon solar cell. We compare device characteristics and efficiencies to standard antireflective coatings applied to a grid contact cell. The effects of the metamaterial contact on silicon solar cell efficiencies is discussed for PN junction and metal-insulator-semiconductor cell structures. It is found that the metal-insulator-semiconductor solar cell designed performs better than the PN junction cell.

  17. Aluminide coatings

    DOEpatents

    Henager, Jr; Charles, H [Kennewick, WA; Shin, Yongsoon [Richland, WA; Samuels, William D [Richland, WA

    2009-08-18

    Disclosed herein are aluminide coatings. In one embodiment coatings are used as a barrier coating to protect a metal substrate, such as a steel or a superalloy, from various chemical environments, including oxidizing, reducing and/or sulfidizing conditions. In addition, the disclosed coatings can be used, for example, to prevent the substantial diffusion of various elements, such as chromium, at elevated service temperatures. Related methods for preparing protective coatings on metal substrates are also described.

  18. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  19. Subwavelength structures for high power laser antireflection application on fused silica by one-step reactive ion etching

    NASA Astrophysics Data System (ADS)

    Ye, Xin; Jiang, Xiao-Dong; Huang, Jin; Sun, Lai-Xi; Geng, Feng; Yi, Zao; Zu, Xiao-Tao; Wu, Wei-Dong; Zheng, Wanguo

    2016-03-01

    In this paper we report a simple method to fabricate a novel subwavelength structure surface on fused silica substrate using one-step reactive ion etching with two-dimensional polystyrene colloidal crystals as masks. The etching process and the morphologies of the obtained structure are controlled. We show that the period of the obtained fused silica pillar-like arrays were determined by the initial polystyrene nanoparticle size. The height of pillar arrays can be adjusted by controlling the etching duration, which is proved to be of importance in tailoring the antireflection properties of subwavelength structures surface. The novel subwavelength structures surface exhibit excellent broadband antireflection properties, but the size of the pillar affects the antireflective properties in short wavelength region. We anticipate this method would offer a convenient and scalable way for inexpensive and high-efficiency high power laser field designs.

  20. Antireflective grassy surface on glass substrates with self-masked dry etching

    PubMed Central

    2013-01-01

    Although recently developed bio-inspired nanostructures exhibit superior optic performance, their practical applications are limited due to cost issues. We present highly transparent glasses with grassy surface fabricated with self-masked dry etch process. Simultaneously generated nanoclusters during reactive ion etch process with simple gas mixture (i.e., CF4/O2) enables lithography-free, one-step nanostructure fabrication. The resulting grassy surfaces, composed of tapered subwavelength structures, exhibit antireflective (AR) properties in 300 to 1,800-nm wavelength ranges as well as improved hydrophilicity for antifogging. Rigorous coupled-wave analysis calculation provides design guidelines for AR surface on glass substrates. PMID:24289255

  1. Antireflective grassy surface on glass substrates with self-masked dry etching

    NASA Astrophysics Data System (ADS)

    Song, Young Min; Park, Gyeong Cheol; Kang, Eun Kyu; Yeo, Chan Il; Lee, Yong Tak

    2013-12-01

    Although recently developed bio-inspired nanostructures exhibit superior optic performance, their practical applications are limited due to cost issues. We present highly transparent glasses with grassy surface fabricated with self-masked dry etch process. Simultaneously generated nanoclusters during reactive ion etch process with simple gas mixture (i.e., CF4/O2) enables lithography-free, one-step nanostructure fabrication. The resulting grassy surfaces, composed of tapered subwavelength structures, exhibit antireflective (AR) properties in 300 to 1,800-nm wavelength ranges as well as improved hydrophilicity for antifogging. Rigorous coupled-wave analysis calculation provides design guidelines for AR surface on glass substrates.

  2. Fabrication of Antireflective Subwavelength Structure on Spherical Glass Surface Using Imprinting Process

    NASA Astrophysics Data System (ADS)

    Tamura, Takamasa; Umetani, Makoto; Yamada, Kazuhiro; Tanaka, Yasuhiro; Kintaka, Kenji; Kasa, Haruya; Nishii, Junji

    2010-11-01

    For the first time, an antireflective structure (ARS) on a convex spherical glass surface was fabricated using an imprinting process. The inverted pattern of the ARS with a 250-nm period was fabricated on a SiC mold with a concave surface using electron beam (EB) direct writing and reactive ion etching. The sample surface height was adjusted to the EB focal position along the mold curvature during the step-and-repeat EB lithography. The imprinted lens with the ARS exhibited surface reflectance of 0.2% at a wavelength of 530 nm and a spherical error magnitude of less than 500 nm.

  3. Antireflection treatment of thickness sensitive spectrally selective (TSSS) paints for thermal solar absorbers

    SciTech Connect

    Lundh, M.; Waeckelgaard, E.; Blom, T.

    2010-01-15

    There are several methods to produce solar absorbers, and one cheap alternative is painted absorbers, preferably painted with a spectrally selective paint. The optical properties of Thickness Sensitive Spectrally Selective (TSSS) paints are, however, limited by the thickness of the paint layer. In this study it is shown that the solar absorptance of two commercial TSSS paints can be increased between 0.01 and 0.02 units with an antireflection treatment using a silicon dioxide layer deposited from silica-gel. It was found that the thermal emittance (100 C) did not change significantly after the treatment. (author)

  4. A novel method to fabricate silicon tubular gratings with broadband antireflection and super-hydrophobicity.

    PubMed

    Gao, Yang; Shi, Tielin; Tan, Xianhua; Liao, Guanglan

    2014-06-01

    We have developed a novel method to fabricate micro/nano structure based on the coherent diffraction lithography, and acquired periodic silicon tubular gratings with deep nano-scale tapered profiles at the top part. The optical properties of these tubular gratings were similar to an effective gradient-index antireflective surface, resulting in a broadband antireflective combining super-hydrophobic behavior. The mechanism of the method was simulated by rigorous coupled wave analysis algorithms. Then coherent diffraction lithography by use of suitable mask, in which periodic micro-scale circular opaque patters were distributed, was realized on the traditional aligner. Due to coherent diffraction, we obtained enough light intensity for photoresist exposure under the center of the opaque area in the mask together with transparent areas. The tapered line profiles and hollow photoresist gratings over large areas could be fabricated on the silicon wafer after development. The dry etching process was carried out, and high aspect ratio silicon tubular gratings with deep tapered profiles at the top were fabricated. The optical property and wettability of the structure were verified, proving that the proposed method and obtained micro/nano structure provide application potential in the future. PMID:24738414

  5. Highly Efficient Flexible Perovskite Solar Cells with Antireflection and Self-Cleaning Nanostructures.

    PubMed

    Tavakoli, Mohammad Mahdi; Tsui, Kwong-Hoi; Zhang, Qianpeng; He, Jin; Yao, Yan; Li, Dongdong; Fan, Zhiyong

    2015-10-27

    Flexible thin film solar cells have attracted a great deal of attention as mobile power sources and key components for building-integrated photovoltaics, due to their light weight and flexible features in addition to compatibility with low-cost roll-to-roll fabrication processes. Among many thin film materials, organometallic perovskite materials are emerging as highly promising candidates for high efficiency thin film photovoltaics; however, the performance, scalability, and reliability of the flexible perovskite solar cells still have large room to improve. Herein, we report highly efficient, flexible perovskite solar cells fabricated on ultrathin flexible glasses. In such a device structure, the flexible glass substrate is highly transparent and robust, with low thermal expansion coefficient, and perovskite thin film was deposited with a thermal evaporation method that showed large-scale uniformity. In addition, a nanocone array antireflection film was attached to the front side of the glass substrate in order to improve the optical transmittance and to achieve a water-repelling effect at the same time. It was found that the fabricated solar cells have reasonable bendability, with 96% of the initial value remaining after 200 bending cycles, and the power conversion efficiency was improved from 12.06 to 13.14% by using the antireflection film, which also demonstrated excellent superhydrophobicity. PMID:26284607

  6. 3D-Printed Broadband Dielectric Tube Terahertz Waveguide with Anti-Reflection Structure

    NASA Astrophysics Data System (ADS)

    Vogt, Dominik Walter; Leonhardt, Rainer

    2016-07-01

    We demonstrate broadband, low loss, and close-to-zero dispersion guidance of terahertz (THz) radiation in a dielectric tube with an anti-reflection structure (AR-tube waveguide) in the frequency range from 0.2 to 1.0 THz. The anti-reflection structure (ARS) consists of close-packed cones in a hexagonal lattice arranged on the outer surface of the tube cladding. The feature size of the ARS is in the order of the wavelength between 0.2 and 1.0 THz. The waveguides are fabricated with the versatile and cost efficient 3D-printing method. Terahertz time-domain spectroscopy (THz-TDS) measurements as well as 3D finite-difference time-domain simulations (FDTD) are performed to extensively characterize the AR-tube waveguides. Spectrograms, attenuation spectra, effective phase refractive indices, and the group-velocity dispersion parameters β 2 of the AR-tube waveguides are presented. Both the experimental and numerical results confirm the extended bandwidth and smaller group-velocity dispersion of the AR-tube waveguide compared to a low loss plain dielectric tube THz waveguide. The AR-tube waveguide prototypes show an attenuation spectrum close to the theoretical limit given by the infinite cladding tube waveguide.

  7. Coating Process

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A black chrome coating, originally developed for spacecraft solar cells, led to the development of an efficient flat plate solar collector. The coating, called Chromonyx, helps the collector absorb more heat. Olympic Solar Corporation was formed to electroplate the collector. The coating technique allows 95% of the sun's energy to be utilized. The process is widely used.

  8. Excellent Passivation and Low Reflectivity Al2O3/TiO2 Bilayer Coatings for n-Wafer Silicon Solar Cells: Preprint

    SciTech Connect

    Lee, B. G.; Skarp, J.; Malinen, V.; Li, S.; Choi, S.; Branz, H. M.

    2012-06-01

    A bilayer coating of Al2O3 and TiO2 is used to simultaneously achieve excellent passivation and low reflectivity on p-type silicon. This coating is targeted for achieving high efficiency n-wafer Si solar cells, where both passivation and anti-reflection (AR) are needed at the front-side p-type emitter. It could also be valuable for front-side passivation and AR of rear-emitter and interdigitated back contact p-wafer cells. We achieve high minority carrier lifetimes {approx}1 ms, as well as a nearly 2% decrease in absolute reflectivity, as compared to a standard silicon nitride AR coating.

  9. Metal Coatings

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During the Apollo Program, General Magnaplate Corporation developed process techniques for bonding dry lubricant coatings to space metals. The coatings were not susceptible to outgassing and offered enhanced surface hardness and superior resistance to corrosion and wear. This development was necessary because conventional lubrication processes were inadequate for lightweight materials used in Apollo components. General Magnaplate built on the original technology and became a leader in development of high performance metallurgical surface enhancement coatings - "synergistic" coatings, - which are used in applications from pizza making to laser manufacture. Each of the coatings is designed to protect a specific metal or group of metals to solve problems encountered under operating conditions.

  10. Effects of long term exposure on optical substrates and coatings (SOO50-2)

    NASA Technical Reports Server (NTRS)

    Vallimont, John; Havey, Keith

    1992-01-01

    Kodak included 12 substrate and coating samples on the Long Duration Exposure Facility (LDEF) structure. There were 3 fused silica and 3 ultra low expansion (ULE(tm)) uncoated glass samples, 2 ULE(tm) samples with a high reflectance silver coating, 2 fused silica samples with an antireflectance coating, and 2 fused silica samples with a solar rejection coating. The sample dimensions were 32 mm diameter by 1 mm thick. A set of duplicate control samples was also manufactured and stored in a controlled environment for comparison purposes. A preliminary evaluation of the flight samples for effects from the 5 year mission showed that a contaminant was deposited on the samples, a micrometeroid impact occurred on one of the samples, and the radiation darkening which was expected for the glass did not occur. The results are presented in more detail.

  11. Investigation of durability of optical coatings in highly purified tritium gas

    SciTech Connect

    Fischer, S.; Schoenung, K.; Bornschein, B.; Rolli, R.; Schaefer, V.; Sturm, M.

    2015-03-15

    Anti-reflection coated windows are part of Raman spectroscopy systems for tritium analytics in the KATRIN experiment and fusion-related applications. Damages of such windows were observed after three months of expo-sure to highly purified tritium gas in the LOOPINO facility. In this work, the origin of the damages was investigated, identified and eliminated. Coating samples manufactured by various physical vapor deposition methods have been tested for durability by exposure to pure tritium gas and subsequent visual inspection. Electron beam deposited coatings showed indications for damage after 17 days of tritium exposure in contrast to samples manufactured by ion assisted deposition or sputtering. An improved coating layout of the sample cell is presented for reliable long-term monitoring of tritium gas using Raman spectroscopy. (authors)

  12. Optical And Protective Properties Of Hard Carbon Coatings

    NASA Astrophysics Data System (ADS)

    Dischler, B.; Bubenzer, A.; Koidl, P.; Brandt, G.

    1983-09-01

    In recent years amorphous carbon coatings found growing interest because of their optical and protective properties. We have deposited hydrogenated amorphous carbon films (a-C:H) from an RF excited discharge in benzene vapour. Substrates include germanium, glass and MgF2. The refractive index can be tuned between 1.8 and 2.2 and efficient antireflection coatings on Ge have been prepared. We have determined the optical absorption from the UV to the IR range (0.2 - 25 μm). A typical 1 µm thick a-C:H film is transparent (> 50% transmission) from 750 nm to the far infrared. Amorphous carbon films are harder than sapphire and are resistant to concentrated acids and bases.

  13. Coated Si microwire array solar cells for better light trapping

    NASA Astrophysics Data System (ADS)

    Lee, Eunsongyi; Gwon, Minji; Cho, Yunae; Kim, Dong-Wook

    2013-09-01

    We investigated optical properties of planar Si wafers and Si microwire (MW) arrays with and without ZnO thin films using the finite-difference time-domain (FDTD) method. Reflectance of the MW array (diameter: 4 μm and period: 12 μm) was smaller than that of the planar wafer in the wavelength range from 400 to 1100 nm, which could be originated from antireflection effects due to low optical density and guided-mode-assisted field enhancement. The reflectance of ZnO (thickness: 50 and 80 nm)-coated MW array was drastically reduced compared with the bare array but somewhat larger than that of the coated planar wafer. This could be attributed to less-confined guided modes in the wires, which was supported by the field distribution simulation results. Our results provide some insights into possible roles of transparent conducting layers on MW arrays for photovoltaic applications.

  14. An amorphous fluoropolymer: Next generation optical coating candidate

    SciTech Connect

    Chow, R.; Loomis, G.E.; Spragge, M.K.; Lindsey, E.L.; Rainer, F.; Ward, R.L.; Kozlowski, M.R.

    1994-05-01

    Anti-reflective (AR) and high reflector (HR) optical coatings were made by physical vapor deposition (PVD) of Teflon AF2400, a perfluorinated amorphous polymer. The AR had the highest laser damage thresholds recorded for PVD coatings at the Lawrence Livermore National Laboratory damage facility. The HR was a multilayer of ZnS and AF2400. The bandwidth was 550 mn, centered at 1064 mn. Single layers of Teflon AF2400 deposited by PVD were characterized optically. The refractive index could be intentionally reduced below the bulk value by varying either deposition rate or substrate temperature. Scanning electron microscopy and nuclear magnetic resonance observations indicated that morphological changes caused the variations in the refractive index rather than compositional changes.

  15. AR coatings on laser crystals for HiPER project

    NASA Astrophysics Data System (ADS)

    Oulehla, Jindřich; Pokorný, Pavel

    2010-08-01

    In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of material for the lasers active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG, Yb:CaF2 samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress resulting from temperature shocks, etc. Coated samples were placed into cryogenic environment in order to simulate conditions similar to those in real life operation. Optical microscopy was used for coating investigation after the conducted experiments.

  16. Optical coatings on laser crystals for HiPER project

    NASA Astrophysics Data System (ADS)

    Oulehla, Jindrich; Pokorný, Pavel; Lazar, Josef

    2011-12-01

    In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research facility) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of the material for the lasers' active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG and Yb:CaF2 samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress from temperature shocks, etc. Coated samples were placed into cryogenic environment in order to simulate conditions similar to those in real life operation. Optical microscopy was used for coating investigation after the conducted experiments.

  17. Optical coatings on laser crystals for HiPER project

    NASA Astrophysics Data System (ADS)

    Oulehla, Jindrich; Pokorný, Pavel; Lazar, Josef

    2011-06-01

    In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of material for the lasers active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG, Yb:CaF2 and Yb:KGW samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress resulting from temperature shocks, etc. Coated samples were placed in a specially designed cryogenic apparatus in order to simulate conditions similar to those in real life operation. Optical microscopy and spectrophotometer measurements were used for coating investigation after the conducted experiments.

  18. Tunable antireflection from conformal Al-doped ZnO films on nanofaceted Si templates

    PubMed Central

    2014-01-01

    Photon harvesting by reducing reflection loss is the basis of photovoltaic devices. Here, we show the efficacy of Al-doped ZnO (AZO) overlayer on ion beam-synthesized nanofaceted silicon for suppressing reflection loss. In particular, we demonstrate thickness-dependent tunable antireflection (AR) from conformally grown AZO layer, showing a systematic shift in the reflection minima from ultraviolet to visible to near-infrared ranges with increasing thickness. Tunable AR property is understood in light of depth-dependent refractive index of nanofaceted silicon and AZO overlayer. This improved AR property significantly increases the fill factor of such textured heterostructures, which reaches its maximum for 60-nm AZO compared to the ones based on planar silicon. This thickness matches with the one that shows the maximum reduction in surface reflectance. PACS 81.07.-b; 42.79.Wc; 81.16.Rf; 81.15.Cd PMID:24808799

  19. GaN microdomes for broadband omnidirectional antireflection for concentrator photovoltaics

    NASA Astrophysics Data System (ADS)

    Han, Lu; McGoogan, Matthew R.; Piedimonte, Tyler A.; Kidd, Ian V.; French, Roger H.; Zhao, Hongping

    2013-03-01

    GaN microdomes are studied as a broadband omnidirectional anti-reflection structure for high efficiency multi-junction concentrated photovoltaics. Comprehensive studies of the effect of GaN microdome sizes and shapes on the light collection efficiency were studied. The three dimensional finite difference time domain (3-D FDTD) method was used to calculate the surface reflectance of GaN microdomes as compared to that of the flat surface. Studies indicate significant reduction of the surface reflectance is achievable by properly designing the microdome structures. Formation of the GaN microdomes with the flexibility to tune the size and shape has been demonstrated by using reactive ion etching (RIE) of both GaN and the self-assembled silica monolayer microspheres. Characterizations of the angle-dependence light surface reflectance for both micro-domes and flat surface show the similar trend as the simulation.

  20. Resist-free antireflective nanostructured film fabricated by thermal-NIL

    NASA Astrophysics Data System (ADS)

    Kang, Young Hun; Han, Jae Hyung; Cho, Song Yun; Choi, Choon-Gi

    2014-05-01

    Resist-free antireflective (AR) nanostructured films are directly fabricated on polycarbonate (PC) film using thermal-nanoimprint lithography (T-NIL) and the moth-eye shape of AR nanostructure is elaborately optimized with different oxygen reactive ion etching conditions. Anodic aluminum oxide (AAO) templates are directly used as master molds of T-NIL for preparation of AR nanostructures on PC film without an additional T-NIL resist. AR nanostructures are well arranged with a period of about 200 nm and diameter of about 150 nm, which corresponds to those of the AAO template mold. The moth-eye AR nanostructures exhibit the average reflectance of 2% in wavelength range from 400 to 800 nm. From the results, highly enhanced AR properties with simple direct imprinting on PC film demonstrate the potential for panel application in the field of flat display, touch screen, and solar cells.

  1. Superhydrophobic, antiadhesive, and antireflective surfaces mediated by hybrid biomimetic salvinia leaf with moth-eye structures

    NASA Astrophysics Data System (ADS)

    Yang, Cho-Yun; Tsai, Yu-Lin; Yang, Cho-Yu; Sung, Cheng-Kuo; Yu, Peichen; Kuo, Hao-Chung

    2014-08-01

    In this paper, we successfully demonstrate multifunctional surfaces based on scaffolding biomimetic structures, namely, hybrid salvinia leaves with moth-eye structures (HSMSs). The novel fabrication process employs scalable polystyrene nanosphere lithography and a lift-off process. Systematic characterizations show the biomimetic HSMS exhibiting superhydrophobic, self-cleaning, antiadhesive, and antireflective properties. Furthermore, the resulting surface tension gradient (known as the Marangoni effect) leads to a superior air retention characteristic in the HSMS under water droplet impact, compared with the traditional hybrid lotus leaf with a moth-eye structure (HLMS). Such results and learnings pave the way towards the attainment and mass deployment of dielectric surfaces with multiple functionalities for versatile biological and optoelectronic applications.

  2. Infrared Wire-Grid Polarizer with Antireflection Structure by Imprinting on Both Sides

    NASA Astrophysics Data System (ADS)

    Yamada, Itsunari; Yamashita, Naoto; Tani, Kunihiko; Einishi, Toshihiko; Saito, Mitsunori; Fukumi, Kouhei; Nishii, Junji

    2012-08-01

    We fabricated infrared wire-grid polarizers with an antireflection (AR) grating structure by the simultaneous imprinting on both sides of a low-toxicity chalcogenide glass (Sb-Ge-Sn-S system). Silicon carbide and glassy carbon plates were used as molds for the direct glass imprinting. A wire-grid polarizer of 100-nm-thick was produced by depositing Al obliquely on the grating. Although the transmittance of the chalcogenide glass substrate was 62-66% in the 8.5-10.5 µm wavelength range, the transverse magnetic (TM) transmittance of the fabricated element became higher than 70% owing to the AR structure. The extinction ratio was larger than 20 dB at 11 µm wavelength.

  3. Modeling and imprint fabrication of an infrared wire-grid polarizer with an antireflection grating structure

    NASA Astrophysics Data System (ADS)

    Yamada, Itsunari; Yamashita, Naoto; Einishi, Toshihiko; Saito, Mitsunori; Fukumi, Kouhei; Nishii, Junji

    2014-05-01

    An infrared wire-grid polarizer with an antireflection (AR) grating structure was fabricated using direct imprint lithography on both sides of a low toxicity chalcogenide glass (Sb-Ge-Sn-S system) simultaneously. The AR grating structure was designed using rigorous coupled-wave analysis theory. Silicon carbide with a grating period of 500 nm and glassy carbon with a grating period of 3 μm were employed as molds. After imprinting, a wire-grid polarizer was made by depositing Al obliquely on the grating. The transverse magnetic (TM) transmittance of the fabricated polarizer was over 70% at 8.5-10.5 μm wavelength, although the transmittance of the glass substrate is 62-66%, and the extinction ratio was over 20 dB at 11 μm wavelength. The polarizer has a high TM transmittance and is cheaper and simpler to fabricate as compared with conventional infrared polarizers.

  4. Enhancement of antireflection property of silicon using nanostructured surface combined with a polymer deposition.

    PubMed

    Ha, Jun Mok; Yoo, Sung Ho; Cho, Jong Hoi; Cho, Yong Hoon; Cho, Sung Oh

    2014-01-01

    Silicon (Si) nanostructures that exhibit a significantly low reflectance in ultraviolet (UV) and visible light wavelength regions are fabricated using a hydrogen etching process. The fabricated Si nanostructures have aperiodic subwavelength structures with pyramid-like morphologies. The detailed morphologies of the nanostructures can be controlled by changing the etching condition. The nanostructured Si exhibited much more reduced reflectance than a flat Si surface: an average reflectance of the nanostructured Si was approximately 6.8% in visible light region and a slight high reflectance of approximately 17% in UV region. The reflectance was further reduced in both UV and visible light region through the deposition of a poly(dimethylsiloxane) layer with a rough surface on the Si nanostructure: the reflectance can be decreased down to 2.5%. The enhancement of the antireflection properties was analyzed with a finite difference time domain simulation method. PMID:24397945

  5. Modification of nanostructured fused silica for use as superhydrophobic, IR-transmissive, anti-reflective surfaces

    NASA Astrophysics Data System (ADS)

    Boyd, Darryl A.; Frantz, Jesse A.; Bayya, Shyam S.; Busse, Lynda E.; Kim, Woohong; Aggarwal, Ishwar; Poutous, Menelaos; Sanghera, Jasbinder S.

    2016-04-01

    In order to mimic and enhance the properties of moth eye-like materials, nanopatterned fused silica was chemically modified to produce self-cleaning substrates that have anti-reflective and infrared transmissive properties. The characteristics of these substrates were evaluated before and after chemical modification. Furthermore, their properties were compared to fused silica that was devoid of surface features. The chemical modification imparted superhydrophobic character to the substrates, as demonstrated by the average water contact angles which exceeded 170°. Finally, optical analysis of the substrates revealed that the infrared transmission capabilities of the fused silica substrates (nanopatterned to have moth eye on one side) were superior to those of the regular fused silica substrates within the visible and near-infrared region of the light spectrum, with transmission values of 95% versus 92%, respectively. The superior transmission properties of the fused silica moth eye were virtually unchanged following chemical modification.

  6. Monolithically integrated micro- and nanostructured glass surface with antiglare, antireflection, and superhydrophobic properties.

    PubMed

    Tulli, Domenico; Hart, Shandon D; Mazumder, Prantik; Carrilero, Albert; Tian, Lili; Koch, Karl W; Yongsunthon, Ruchirej; Piech, Garrett A; Pruneri, Valerio

    2014-07-23

    Hierarchical micro- and nanostructured surfaces have previously been made using a variety of materials and methods, including particle deposition, polymer molding, and the like. These surfaces have attracted a wide variety of interest for applications including reduced specular reflection and superhydrophobic surfaces. To the best of our knowledge, this paper reports the first monolithic, hierarchically structured glass surface that combines micro- and nanoscale surface features to simultaneously generate antiglare (AG), antireflection (AR), and superhydrophobic properties. The AG microstructure mechanically protects the AR nanostructure during wiping and smudging, while the uniform composition of the substrate and the micro- and nanostructured surface enables ion exchange through the surface, so that both the substrate and structured surface can be simultaneously chemically strengthened. PMID:24960031

  7. Tunable antireflection from conformal Al-doped ZnO films on nanofaceted Si templates

    NASA Astrophysics Data System (ADS)

    Basu, Tanmoy; Kumar, Mohit; Sahoo, Pratap Kumar; Kanjilal, Aloke; Som, Tapobrata

    2014-04-01

    Photon harvesting by reducing reflection loss is the basis of photovoltaic devices. Here, we show the efficacy of Al-doped ZnO (AZO) overlayer on ion beam-synthesized nanofaceted silicon for suppressing reflection loss. In particular, we demonstrate thickness-dependent tunable antireflection (AR) from conformally grown AZO layer, showing a systematic shift in the reflection minima from ultraviolet to visible to near-infrared ranges with increasing thickness. Tunable AR property is understood in light of depth-dependent refractive index of nanofaceted silicon and AZO overlayer. This improved AR property significantly increases the fill factor of such textured heterostructures, which reaches its maximum for 60-nm AZO compared to the ones based on planar silicon. This thickness matches with the one that shows the maximum reduction in surface reflectance.

  8. Forming high efficiency silicon solar cells using density-graded anti-reflection surfaces

    DOEpatents

    Yuan, Hao-Chih; Branz, Howard M.; Page, Matthew R.

    2014-09-09

    A method (50) is provided for processing a graded-density AR silicon surface (14) to provide effective surface passivation. The method (50) includes positioning a substrate or wafer (12) with a silicon surface (14) in a reaction or processing chamber (42). The silicon surface (14) has been processed (52) to be an AR surface with a density gradient or region of black silicon. The method (50) continues with heating (54) the chamber (42) to a high temperature for both doping and surface passivation. The method (50) includes forming (58), with a dopant-containing precursor in contact with the silicon surface (14) of the substrate (12), an emitter junction (16) proximate to the silicon surface (14) by doping the substrate (12). The method (50) further includes, while the chamber is maintained at the high or raised temperature, forming (62) a passivation layer (19) on the graded-density silicon anti-reflection surface (14).

  9. Forming high-efficiency silicon solar cells using density-graded anti-reflection surfaces

    DOEpatents

    Yuan, Hao-Chih; Branz, Howard M.; Page, Matthew R.

    2015-07-07

    A method (50) is provided for processing a graded-density AR silicon surface (14) to provide effective surface passivation. The method (50) includes positioning a substrate or wafer (12) with a silicon surface (14) in a reaction or processing chamber (42). The silicon surface (14) has been processed (52) to be an AR surface with a density gradient or region of black silicon. The method (50) continues with heating (54) the chamber (42) to a high temperature for both doping and surface passivation. The method (50) includes forming (58), with a dopant-containing precursor in contact with the silicon surface (14) of the substrate (12), an emitter junction (16) proximate to the silicon surface (14) by doping the substrate (12). The method (50) further includes, while the chamber is maintained at the high or raised temperature, forming (62) a passivation layer (19) on the graded-density silicon anti-reflection surface (14).

  10. Investigation of the neutral-solution etch process for refractive SOE antireflective surfaces

    SciTech Connect

    Maish, A.B.

    1991-01-01

    Antireflection of optically clear glass used in photovoltaic concentrator refractive secondary optical elements (SOE's) was investigated using the neutral-solution etch process developed by Schott Glass. Test coupons and SOE's made from barium zinc glass, which does not solarize under ultraviolet exposure, were successfully etched at the center point process variable conditions of 87{degrees}C and 24 hours. Reflectance of the plano-plano dropped from 7.7% to 0.8%, with a corresponding increase in transmission from 91.7% to 98.5%. The etching process uses non-hydrofluoric, relatively non-toxic chemicals in a low-cost process well suited for use by photovoltaic system manufacturers during production. 10 refs., 4 figs., 1 tab.

  11. Antireflective subwavelength structures on microlens arrays-comparison of various manufacturing techniques.

    PubMed

    Pacholski, Claudia; Morhard, Christoph; Spatz, Joachim P; Lehr, Dennis; Schulze, Marcel; Kley, Ernst-Bernhard; Tünnermann, Andreas; Helgert, Michael; Sundermann, Michael; Brunner, Robert

    2012-01-01

    Antireflective subwavelength structures (ARS) resembling nanostructures found on the cornea of night-active insects reduce the reflection of light by providing a gradual change in the refractive index at the interface. These artificial ARS have mainly been fabricated by a combination of conventional lithography and reactive ion etching, which constrains their application to planar substrates. We report on the fabrication of ARS using three different techniques including bottom-up and top-down methods as well as their combination on microlens arrays (MLAs) made of fused silica. The optical performance of the resulting ARS on the MLAs is as good as ARS fabricated on planar substrates with increased transmission of up to 96% at certain wavelengths. PMID:22270407

  12. Superhydrophobic antireflective silica films: fractal surfaces and laser-induced damage thresholds.

    PubMed

    Xu, Yao; Wu, Dong; Sun, Yu Han; Huang, Zu Xing; Jiang, Xiao Dong; Wei, Xiao Feng; Li, Zhi Hong; Dong, Bao Zhong; Wu, Zhong Hua

    2005-02-01

    Several superhydrophobic antireflective silica films have been prepared by a solgel method that uses hexamethyl-disilizane (HMDS) as a modifier. In a high-power laser, laser-induced damage thresholds (LIDTs) of 23-30 J/cm2 were obtained at 1064-nm wavelength with 1-ns pulse duration. By atomic-force microscopy and optical microscopy, the fractal surfaces of films were studied, and multifractal spectra (MFSs) were calculated both before and after laser damage. The two-sided effect of HMDS on particle growth determined the surface fractal of a particle and the multifractal structure of a film's surface. The bigger deltaalpha was, both before and after laser damage, the lower the LIDT was. The effect of methyl groups should be included in the determination of the MFS of the LIDT. PMID:15726949

  13. Superhydrophobic antireflective silica films: fractal surfaces and laser-induced damage thresholds

    NASA Astrophysics Data System (ADS)

    Xu, Yao; Wu, Dong; Sun, Yu Han; Huang, Zu Xing; Jiang, Xiao Dong; Wei, Xiao Feng; Li, Zhi Hong; Zhong Dong, Bao; Wu, Zhong Hua

    2005-02-01

    Several superhydrophobic antireflective silica films have been prepared by a solgel method that uses hexamethyl-disilizane (HMDS) as a modifier. In a high-power laser, laser-induced damage thresholds (LIDTs) of 23-30 J/cm2 were obtained at 1064-nm wavelength with 1-ns pulse duration. By atomic-force microscopy and optical microscopy, the fractal surfaces of films were studied, and multifractal spectra (MFSs) were calculated both before and after laser damage. The two-sided effect of HMDS on particle growth determined the surface fractal of a particle and the multifractal structure of a film's surface. The bigger Deltaa was, both before and after laser damage, the lower the LIDT was. The effect of methyl groups should be included in the determination of the MFS of the LIDT.

  14. Morbus Coats

    PubMed Central

    Förl, B.; Schmack, I.; Grossniklaus, H.E.; Rohrschneider, K.

    2010-01-01

    Der fortgeschrittene Morbus Coats stellt im Kleinkindalter eine der schwierigsten Differenzialdiagnosen zum Retinoblastom dar. Wir beschreiben die klinischen und histologischen Befunde zweier Jungen im Alter von 9 und 21 Monaten mit einseitiger Leukokorie. Trotz umfassender Diagnostik mittels Narkoseuntersuchung, MRT und Ultraschall konnte ein Retinoblastom nicht sicher ausgeschlossen werden, und es erfolgte eine Enukleation. Histologisch wurde die Diagnose eines Morbus Coats gesichert. Da eine differenzialdiagnostische Abgrenzung zwischen Morbus Coats und Retinoblastom schwierig sein kann, halten wir in zweifelhaften Fällen auch angesichts der eingeschränkten Visusprognose und potenzieller Sekundärkomplikationen beim fortgeschrittenen Morbus Coats eine Enukleation für indiziert. PMID:18299842

  15. The Development, Application And Testing Of Diamond-Like Coatings For Infra-Red Components

    NASA Astrophysics Data System (ADS)

    Lettington, A. H.

    1986-05-01

    The lack of durability of the outermost coated lens or window of thermal imaging systems had been a problem for many years. It was overcome in the mid-seventies by the development within RSRE of the infra-red transparent diamond-like carbon coating. This material was chemically durable, abrasion resistant and a near perfect match to germanium as a single layer anti-reflection coating. Originally the coatings had reasonable infra-red transmission but their hardness and adhesion were variable. Using our own processes we obtained consistently good coatings with optimised transmission. The application and excellent performance of these coatings on germanium components is described. Another application is the protection of diamond flycut aluminium surfaces where the off-normal reflectivity in the infra-red using conventional coatings can be poor. Having developed these coatings it was then necessary to develop specifications before they could be used in service. The development of coatings test procedures and specifications is also described.

  16. Fabrication of highly transparent diamond-like carbon anti-reflecting coating for Si solar cell application

    SciTech Connect

    Banerjee, Amit Das, Debajyoti

    2014-04-24

    ARC grade highly transparent unhydrogenated diamond-like carbon (DLC) films were produced, directly from a-C target, using RF magnetron sputtering deposition technique, for optoelectronic applications. Optical band gap, transmittance, reflectance, sp{sup 3} fraction, I{sub D}/I{sub G}, density, and refractive index of the films have been estimated with the help of optical tools like Uv-vis spectrophotometer, ellipsometer and micro-Raman. Optimum ARC-qualities have been identified in low-temperature grown DLC films at an Ar pressure of 4 mTorr in the reactor, accomplishing its key requirements for use in silicon solar cells.

  17. Back-side-coated chirped mirrors with ultra-smooth broadband dispersion characteristics

    NASA Astrophysics Data System (ADS)

    Matuschek, N.; Gallmann, L.; Sutter, D. H.; Steinmeyer, G.; Keller, U.

    We demonstrate a new technique for the design of chirped mirrors with extremely smooth dispersion characteristics over an extended ultra-broadband wavelength range. Our approach suppresses spectral dispersion oscillations, which can lead to unwanted strong spectral modulations and limit the bandwidth of mode-locked laser pulses. Dispersion oscillations are significantly reduced by coating the chirped mirror structure on the back side of a substrate, providing ideal impedance matching between coating and ambient medium. An anti-reflection coating may be added on the front side of the substrate, geometrically separated from the chirped mirror. The chirped mirror structure and the anti-reflection coating are non-interfering and can be independently designed and optimized. The separation of both coating sections provides a much better solution for the impedance-matching problems than previous approaches to chirped mirror design. We show by a theoretical analysis and numerical simulations that minimum dispersion oscillations are achieved if the index of the substrate is identical to the index of one of the coating materials and if double-chirping is used for the chirped mirror structure. Based on this analysis, we design a mirror that supports a bandwidth of 220 THz with group delay dispersion oscillations of about 2 fs2 (rms), an order-of magnitude improvement compared to previous designs of similar bandwidth. In a first experimental demonstration of back-side-coated (BASIC) mirrors, we achieve nearly transform-limited and virtually unchirped pulses of 5.8 fs duration from a Kerr-lens mode-locked Ti:sapphire laser. BASIC mirrors are particularly suited for higher-order dispersion compensation schemes. They support the extremely broad spectra of few-cycle pulses and promise to provide clean pulse shapes in this regime.

  18. Coatings Guide

    EPA Science Inventory

    The Coatings Guide is a free online information resource that focuses on alternative, low-emission coatings for metal, plastic, and architectural substrates. Developed cooperatively by the U.S. EPA's Office of Research and Development and Research Triangle Institute (RTI) Interna...

  19. Low-temperature thermal nanoimprint lithography of anti-reflective structures for flexible low band gap organic solar cells

    NASA Astrophysics Data System (ADS)

    Kettle, J.; Rees, A.; Brousseau, E. B.; Horie, M.

    2013-03-01

    The effect of adding anti-reflective structures to a PCPDTBT : PCBM organic solar cell on a flexible substrate using a one-step thermal-nanoimprint lithography process has been studied. In order to process nanostructures onto polyethylene terephthalate (PET) substrates, a low glass transition polymer was used. The power conversion efficiency (PCE) was increased by 4% when the light was irradiated at normal incidence. However, at oblique angles of incidence (80°), a 32% relative increase in PCE was observed showing the enhanced light-capturing capability of the anti-reflective features. This efficiency enhancement was attributed to reduced reflection at the air-PET interface, which is supported by optical modelling data.

  20. Anti- reflective device having an anti-reflection surface formed of silicon spikes with nano-tips

    NASA Technical Reports Server (NTRS)

    Bae, Youngsman (Inventor); Mooasser, Sohrab (Inventor); Manohara, Harish (Inventor); Lee, Choonsup (Inventor); Bae, Kungsam (Inventor)

    2009-01-01

    Described is a device having an anti-reflection surface. The device comprises a silicon substrate with a plurality of silicon spikes formed on the substrate. A first metallic layer is formed on the silicon spikes to form the anti-reflection surface. The device further includes an aperture that extends through the substrate. A second metallic layer is formed on the substrate. The second metallic layer includes a hole that is aligned with the aperture. A spacer is attached with the silicon substrate to provide a gap between an attached sensor apparatus. Therefore, operating as a Micro-sun sensor, light entering the hole passes through the aperture to be sensed by the sensor apparatus. Additionally, light reflected by the sensor apparatus toward the first side of the silicon substrate is absorbed by the first metallic layer and silicon spikes and is thereby prevented from being reflected back toward the sensor apparatus.

  1. Low-cost, flexible, and self-cleaning 3D nanocone anti-reflection films for high-efficiency photovoltaics.

    PubMed

    Tsui, Kwong-Hoi; Lin, Qingfeng; Chou, Hungtao; Zhang, Qianpeng; Fu, Huiying; Qi, Pengfei; Fan, Zhiyong

    2014-05-01

    Low-cost engineered nanotemplates are used to mold flexible nanocone anti-reflection (AR) films. Both optical reflectance measurements and photovoltaics characterizations demonstrate that the flexible nanocone AR films can considerably suppress device front-side reflectance and thus improve the power conversion efficiency of high-efficiency thin-film CdTe solar cells. Additionally, these nanocone AR films are found to be superhydrophobic and thus possess self-cleaning capability. PMID:24448979

  2. Regulatory Aspects of Coatings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter gives a history of the development and uses of edible coating regulations, detailed chapters on coating caracteristics, determination of coating properties, methods for making coatings, and discription of coating film formers (polysaccharieds, lipids, resins, proteins). The chapter also...

  3. Sol-gel preparation and characterization of SiO2 coated VO2 films with enhanced transmittance and high thermochromic performance

    NASA Astrophysics Data System (ADS)

    Li, Dezeng; Shan, Yongkui; Huang, Fuqiang; Ding, Shangjun

    2014-10-01

    Vanadium dioxide (VO2) films prepared at low-temperature with a low cost are considerable for energy-saving applications. Here, SiO2 coated VO2 films with clearly enhanced visible transmittance by introducing antireflection coatings (ARCs) and excellent thermochromic performance were present. The VO2 films have been prepared via a stable and low-cost sol-gel synthesis route using vanadium pentaoxide powder as precursor, and their structural, morphological, optical and electrical properties and thermochromic performance were systemically characterized. The resistance of VO2 films varies by 4 orders of magnitude and the transmittance changes from 11.8% to 69.3% at 2500 nm while no significant deviation appears in the visible region during metal-insulator transition (MIT). Nanoporous SiO2 coating with good optical transparency was coated on the surface of VO2 film via sol-gel dip-coating technique to enhance its optical transmittance, and the visible transmittance is increased by 14.6% due to the significantly decreased reflectance. The critical transition temperature (63 °C) and infrared switching properties of VO2 films are not much deteriorated by applying SiO2 layer. The synergistic effect of antireflection and thermochromism on SiO2 coated VO2 films was investigated.

  4. Structure and antireflection properties of SiNWs arrays form mc-Si wafer through Ag-catalyzed chemical etching

    NASA Astrophysics Data System (ADS)

    Li, Shaoyuan; Ma, Wenhui; Chen, Xiuhua; Xie, Keqiang; Li, Yuping; He, Xiao; Yang, Xi; Lei, Yun

    2016-04-01

    A simple and low cost MACE method was demonstrated for efficiently texturing commercial mc-Si wafer at room temperature. The effects of fabrication parameters (deposition time, HF concentration, H2O2 concentration, and etching time) on the morphology structure, antireflection property of textured mc-Si were carefully studied. The large scale SiNWs arrays with different structure can be obtained under various fabrication conditions. Meanwhile, the results indicate that the fabricate parameters have important effect on the reflectance of textured mc-Si sample in the order of etching time > deposition time > H2O2 concentration > HF concentration. The comprehensive research results indicate that it is more beneficial for the nanowire arrays with tapering structure and the length of 13 μm to obtain excellent antireflection property. Under these optimization conditions, the textured mc-Si shows an outstanding anti-reflectance ability of ∼5.6%, which indicates that the Ag-catalysis etched mc-Si shows a huge potential application in high-efficiency polysilicon solar cells.

  5. Protective Coatings

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Ameron International Protective Coatings Group developed a special coating for NASA that would withstand the high temperatures generated by the Space Shuttle rocket engines. The coating remains intact for at least 10 minutes, and insulates the launch pad so that it does not exceed 150 degrees and buckle. The NASA formulation was from Ameron's Engineered Siloxane (PSX) chemistry, which employs an inorganic silicon-oxygen structure which the company states is stronger and more reliable than organic polymers. Some of Ameron's PSX product line is based on the NASA technology, used for everything from industrial equipment to bridges.

  6. Sprayed coatings

    NASA Astrophysics Data System (ADS)

    Steffens, H. D.

    1980-03-01

    Thermal spraying is shown to be an efficient means for the protection of surface areas against elevated temperature, wear, corrosion, hot gas corrosion, and erosion in structural aircraft components. Particularly in jet engines, numerous parts are coated by flame, detonation, or plasma spraying techniques. The applied methods of flame, detonation, and plasma spraying are explained, as well as electric arc spraying. Possibilities for spray coatings which meet aircraft service requirements are discussed, as well as methods for quality control, especially nondestructive test methods. In particular, coating characteristics and properties obtained by different spray methods are described, and special attention is paid to low pressure plasma spraying.

  7. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, R.; Loomis, G.E.; Thomas, I.M.

    1999-03-16

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (ca. 1.10--1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm. 2 figs.

  8. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, Robert; Loomis, Gary E.; Thomas, Ian M.

    1999-01-01

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (.about.1.10-1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm.

  9. Towards perfect light coupling and absorption in nanomembranes with omni-directional anti-reflection and photonic crystal structures

    NASA Astrophysics Data System (ADS)

    Chadha, Arvinder Singh

    investigated in detail. The front-surface Fresnel reflection is reduced with the incorporation of an omni-directional anti-reflection coating (Omni-ARC) based on nanostructures or by deposition of graded refractive index (GRIN) films. A design methodology based on the comparison of the rate of change of the refractive index profile of nanostructures of different shapes and thickness as an equivalent GRIN film suggests the minimum feature size needed to give near perfect ARC. Numerical models were built to account for the non - uniform GRIN film deposition on both rigid and flexible, flat and curved surfaces resulting from the variation in the resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) process technology. With the miniaturization of the devices, the effect of finite beam size and finite active area of the photonic components on the optical properties like transmission, reflection and scattering loss was studied as well. All the numerical studies presented in the thesis are validated by experimental results.

  10. Large-Aperture Wide-Bandwidth Anti-Reflection-Coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, E. J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, M. A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for sub-millimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n = 3.4, low loss, and relatively high thermal conductivity is a nearly optimal material for these purposes, but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coffecient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated and coated silicon lenses as large as 33.4 cm in diameter with coatings optimized for use between 125-165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30 deg. with low cross-polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to sub-millimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  11. Versatile Coating

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A radome at Logan Airport and a large parabolic antenna at the Wang Building in Massachusetts are protected from weather, corrosion and ultraviolet radiation by a coating, specially designed for antennas and radomes, known as CRC Weathertite 6000. The CRC 6000 line that emerged from Boyd Coatings Research Co., Inc. is a solid dispersion of fluorocarbon polymer and polyurethane that yields a tough, durable film with superior ultraviolet resistance and the ability to repel water and ice over a long term. Additionally, it provides resistance to corrosion, abrasion, chemical attacks and impacts. Material can be used on a variety of substrates, such as fiberglass, wood, plastic and concrete in addition to steel and aluminum. In addition Boyd Coatings sees CRC 6000 applicability as an anti-icing system coated on the leading edge of aircraft wings.

  12. Protective Coating

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Inorganic Coatings, Inc.'s K-Zinc 531 protective coating is water-based non-toxic, non-flammable and has no organic emissions. High ratio silicate formula bonds to steel, and in 30 minutes, creates a very hard ceramic finish with superior adhesion and abrasion resistance. Improved technology allows application over a minimal commercial sandblast, fast drying in high humidity conditions and compatibility with both solvent and water-based topcoats. Coating is easy to apply and provides long term protection with a single application. Zinc rich coating with water-based potassium silicate binder offers cost advantages in materials, labor hours per application, and fewer applications over a given time span.

  13. Multifunctional porous silicon nanopillar arrays: antireflection, superhydrophobicity, photoluminescence, and surface-enhanced Raman scattering (SERS)

    PubMed Central

    Kiraly, Brian; Yang, Shikuan

    2014-01-01

    We have fabricated porous silicon nanopillar arrays over large areas with a rapid, simple, and low-cost technique. The porous silicon nanopillars show unique longitudinal features along their entire length and have porosity with dimensions on the single-nanometer scale. Both Raman spectroscopy and photoluminescence data were used to determine the nanocrystallite size to be < 3 nm. The porous silicon nanopillar arrays also maintained excellent ensemble properties, reducing reflection nearly fivefold from planar silicon in the visible range without any optimization and approaching superhydrophobic behavior with increasing aspect ratio, demonstrating contact angles up to 138°. Finally, the porous silicon nanopillar arrays were made into sensitive surface enhanced Raman scattering (SERS) substrates by depositing metal onto the pillars. The SERS performance of the substrates was demonstrated using a chemical dye Rhodamine 6G. With their multitude of properties (i.e., antireflection, superhydrophobicity, photoluminescence, and sensitive SERS), the porous silicon nanopillar arrays described here can be valuable in applications such as solar harvesting, electrochemical cells, self-cleaning devices, and dynamic biological monitoring. PMID:23703091

  14. Broadband terahertz anti-reflective structure fabricated by femtosecond laser drilling technique

    NASA Astrophysics Data System (ADS)

    Zhang, Yibin; Yuan, Minghui; Chen, Lin; Cai, Bin; Yang, Rui; Zhu, Yiming

    2016-02-01

    We fabricated several reverse conical holes on high-resistivity silicon substrate with different power and pulse number of femtosecond laser, and investigated their patterns and features by using scanning electron microscope (SEM). Then, we chose one of the experimental parameters prepared a reverse conical anti-reflection structure sample with period of 90 μm. Terahertz Time-domain Spectroscopy (THz-TDS) was used to test its properties. Compared with the nonstructural high-resistivity silicon, the transmission of structural high-resistivity silicon increases by the maximum of 14% in the range 0.32-1.30 THz. Furthermore, we simulated the sample by finite integral method (FIM). The simulated results show good consistency with experimental results. The transmission effect of the reverse conical holes were optimized via simulation. Results show that the related transmission effect can be improved by increasing the pulse numbers and decreasing the spot size of the femtosecond laser. The different transmission window can also be tuned by changing the reverse conical structure of different periods.

  15. Large-area, size-tunable Si nanopillar arrays with enhanced antireflective and plasmonic properties

    NASA Astrophysics Data System (ADS)

    Niu, Lihong; Jiang, Xiaohong; Zhao, Yaolong; Ma, Haiguang; Yang, Jingjing; Cheng, Ke; Du, Zuliang

    2016-08-01

    In this paper, a novel method using the modified Langmuir–Blodgett and float-transfer techniques was introduced to construct the perfect PS monolayer nanosphere template with large area up to cm2. Based on such templates, the diameter, length, packing density, and the shape of Si nanopillar arrays (Si NPAs) could be precisely controlled and tuned through the modified nanosphere lithography combined with a metal-assisted chemical etching (NSL-MACE) method. Manipulation of the etching time can effectively avoid permanent deformation/clumping to generate size-tunable Si NPAs. The optical properties of the Si NPAs can be controlled by the Si NPA morphologies resulting from the different reactive ion etching (RIE) time and chemical etching time. The enhanced antireflective property and electromagnetic field effect of Au/Si NPAs were proved by the results. The new modified NSL-MACE technique with the capability of scale-up fabrication of Si NPAs would be helpful for potential applications in optoelectronic devices.

  16. Large-area, size-tunable Si nanopillar arrays with enhanced antireflective and plasmonic properties.

    PubMed

    Niu, Lihong; Jiang, Xiaohong; Zhao, Yaolong; Ma, Haiguang; Yang, Jingjing; Cheng, Ke; Du, Zuliang

    2016-08-01

    In this paper, a novel method using the modified Langmuir-Blodgett and float-transfer techniques was introduced to construct the perfect PS monolayer nanosphere template with large area up to cm(2). Based on such templates, the diameter, length, packing density, and the shape of Si nanopillar arrays (Si NPAs) could be precisely controlled and tuned through the modified nanosphere lithography combined with a metal-assisted chemical etching (NSL-MACE) method. Manipulation of the etching time can effectively avoid permanent deformation/clumping to generate size-tunable Si NPAs. The optical properties of the Si NPAs can be controlled by the Si NPA morphologies resulting from the different reactive ion etching (RIE) time and chemical etching time. The enhanced antireflective property and electromagnetic field effect of Au/Si NPAs were proved by the results. The new modified NSL-MACE technique with the capability of scale-up fabrication of Si NPAs would be helpful for potential applications in optoelectronic devices. PMID:27345038

  17. Realization of effective light trapping and omnidirectional antireflection in smooth surface silicon nanowire arrays.

    PubMed

    Xie, W Q; Oh, J I; Shen, W Z

    2011-02-11

    We have successfully fabricated well-ordered silicon nanowire (SiNW) arrays of smooth surface by using a low-cost and facile Ag-assisted chemical etching technique. We have experimentally found that the reflectance can be significantly suppressed (<1%) over a wide solar spectrum (300-1000 nm) in the as-grown samples. Also, based on our bundled model, we have used rigorous coupled-wave analysis to simulate the reflectance in SiNW arrays, and found that the calculated results are in good agreement with the experimental data. From a further simulation study on the light absorption in SiNW arrays, we have obtained a photocurrent enhancement of up to 425% per unit volume of material as compared to crystalline Si, implying that effective light trapping can be realized in the as-grown samples. In addition, we have demonstrated experimentally and theoretically that the as-grown samples have an omnidirectional high-efficiency antireflection property. PMID:21212474

  18. Nanofeatured anti-reflective films manufactured using hot roller imprinting and self-assembly nanosphere lithography

    NASA Astrophysics Data System (ADS)

    Liu, Shih-Jung; Chen, Wei-An

    2013-06-01

    This paper details the continuous fabrication of nanofeatured anti-reflective films for solar cells, using hot roller imprinting and self-assembly nanosphere lithography. Polystyrene nanospheres of different sizes (471, 628, and 1200 nm) were first self-assembled onto Silicon substrates by a spin coater. A thin layer of aluminum was then deposited onto the surface of nanosphere-patterned substrates, using the plasma sputtering technique. After electroforming, nickel-cobalt membranes containing nano-arrays of different sizes were obtained. The membranes were then attached to the surface of the metallic roller in a hot roller imprinting facility. The imprinting facility was used to replicate the nanofeatures onto 60 μm thick polyethylene terephthalate (PET) films. The imprinted films were characterized using water contact angle measurement, a UV-vis spectrophotometer, atomic force microscope (AFM), and scanning electron microscope (SEM); the enhancement efficiency of the nanofeatured films for the solar cells was also measured by a solar simulator. The measured results suggested that the imprinted films could effectively reduce the reflectance and increase the conversion efficiency of solar cells.

  19. Practical resolution enhancement effect by new complete antireflective layer in KrF excimer laser lithography

    NASA Astrophysics Data System (ADS)

    Ogawa, Tohru; Kimura, Mitsumori; Gocho, Tetsuo; Tomo, Yoichi; Tsumori, Toshiro

    1993-08-01

    A new complete anti-reflective layer (ARL) for KrF excimer laser lithography, which becomes an excimer laser lithography to a practical mass production tool beyond 0.35 micrometers rule devices, is developed. This new ARL, whose material is a type of hydro silicon oxynitride film (SiOxNy:H), can be applied to tungsten silicide (W-Si) and even to aluminum silicon (Al- Si) substrates by controlling deposition conditions in plasma enhanced chemical vapor deposition systems. Using this SiOxNy:H film with 30 nm and 25 nm thicknesses on W-Si and Al-Si substrates respectively, critical dimension variations for both substrates are drastically reduced to within 0.02 micrometers for 0.30 micrometers imaging. On actual device structures, with these SiOxNy:H film as an ARL, notching effects by halation are completely reduced. Moreover, these SiOxNy:H film can not only be deposited with topographical uniformity but also etched with conventional SiO2 etching conditions. Another advantage with ARL is a depth of focus enhancement effect. With a SiOxNy:H film depth of focus for the critical dimension is enlarged more than 23% for 0.35 micrometers line and space patterns. Accordingly, practical resolution is enhanced. From the above effect, the limitations of KrF excimer laser lithography for ideal substrate conditions are considered from the point of view of optimal projection lens NA for various feature sizes.

  20. Durable solgel antireflective films with high laser-induced damage thresholds for inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Xu, Yao; Zhang, Lei; Wu, Dong; Sun, Yu Han; Huang, Zu Xing; Jiang, Xiao Dong; Wei, Xiao Feng; Li, Zhi Hong; Dong, Bao Zhong; Wu, Zhong Hua

    2005-04-01

    We tested the use of two hydrophobic methyl-substituted silane precursors, methyltriethoxysilane and dimethyldiethoxysilane, to synthesize methyl-modified silica sols by a two-step method and a cohydrolysis method to produce durable antireflective films with high laser-induced-damage thresholds (LIDTs). Using small-angle x-ray scattering technology, we obtained details of the microstructure of clusters in sol and found various double fractal structural characteristics in the methyl-modified silica clusters; our findings were confirmed by transmission-electron micrographs. Through a 29Si magic-angle spin nuclear magnetic resonance study of the corresponding xerogels, we determined the double-fractal microstructure, which we then related to the LIDTs of AR films. The distribution configuration of methyls in clusters determined the double-fractal microstructure of clusters and then the LIDTs of AR films. The LIDTs of films produced by the cohydrolysis method (the highest was 38 J/cm2 for 1-ns, 1064-nm laser action) were much higher than those from the two-step method because of the loose netlike clusters in the former configuration. During the 220-day aging, the transmittance of hydrophobic AR film decreased ~0.2%. So it is practicable to prepare durable AR films with higher LIDTs than those of normal AR SiO2 films only by introducing hydrophobic methyls into a Si-O-Si matrix of clusters if an appropriate hydrophobic precursor is chosen.

  1. Fabrication of broadband quasi-omnidirectional antireflective surface on glass for photovoltaic application

    NASA Astrophysics Data System (ADS)

    Kumar, Arvind; Kumar, Praveen; Srinivas, G.; Jakeer Khan G., H.; Siju, Barshilia, Harish C.

    2016-05-01

    In this paper, we have demonstrated a simple and cost effective HF-vapor phase etching method to fabricate the broadband quasi-omnidirectional antireflective surface on glass substrate. Both-sides etched sodalime glass substrates under optimized conditions showed a broadband enhancement in the transmittance spectra with maximum transmittance as high as ~97% at 598 nm. FESEM results confirmed the formation of a graded nanoporous surface, which lowers it refractive index. The etched surface exhibited excellent AR property over a wide range of incidence angles (8°-48°), which is attributed due to the formation of graded porosity. Silicon solar cell covered with plain glass showed Isc of 0.123A and efficiency of 8.76%, while it showed Isc of 0.130A and efficiency of 9.2% when it was covered by etched glass. Furthermore, it exhibited an excellent anti-soiling property as compared to plain glass. All these results show its strong potential in the photovoltaic application.

  2. Multiscale ommatidial arrays with broadband and omnidirectional antireflection and antifogging properties by sacrificial layer mediated nanoimprinting.

    PubMed

    Raut, Hemant Kumar; Dinachali, Saman Safari; Loke, Yee Chong; Ganesan, Ramakrishnan; Ansah-Antwi, Kwadwo Konadu; Góra, Aleksander; Khoo, Eng Huat; Ganesh, V Anand; Saifullah, Mohammad S M; Ramakrishna, Seeram

    2015-02-24

    Moth's eye inspired multiscale ommatidial arrays offer multifunctional properties of great significance in optoelectronic devices. However, a major challenge remains in fabricating these arrays on large-area substrates using a simple and scalable technique. Here we present the fabrication of these multiscale ommatidial arrays over large areas by a distinct approach called sacrificial layer mediated nanoimprinting, which involves nanoimprinting aided by a sacrificial layer. The fabricated arrays exhibited excellent pattern uniformity over the entire patterned area. Optimum dimensions of the multiscale ommatidial arrays determined by the finite-difference time domain simulations served as the design parameters for replicating the arrays on glass. A broadband suppression of reflectance to a minimum of ∼1.4% and omnidirectional antireflection for highly oblique angles of incidence up to 70° were achieved. In addition, superhydrophobicity and superior antifogging characteristics enabled the retention of optical properties even in wet and humid conditions, suggesting reliable optical performance in practical outdoor conditions. We anticipate that these properties could potentially enhance the performance of optoelectronic devices and minimize the influence of in-service conditions. Additionally, as our technique is solely nanoimprinting-based, it may enable scalable and high-throughput fabrication of multiscale ommatidial arrays. PMID:25634665

  3. Enhanced power generation in concentrated photovoltaics using broadband antireflective coverglasses with moth eye structures.

    PubMed

    Song, Young Min; Jeong, Yonkil; Yeo, Chan Il; Lee, Yong Tak

    2012-11-01

    We present the effect of broadband antireflective coverglasses (BARCs) with moth eye structures on the power generation capability of a sub-receiver module for concentrated photovoltaics. The period and height of the moth eye structures were designed by a rigorous coupled-wave analysis method in order to cover the full solar spectral ranges without transmission band shrinkage. The BARCs with moth eye structures were prepared by the dry etching of silver (Ag) nanomasks, and the fabricated moth eye structures on coverglass showed strongly enhanced transmittance compared to the bare glass with a flat surface, at wavelengths of 300 - 1800 nm. The BARCs were mounted on InGaP/GaAs/Ge triple-junction solar cells and the power conversion efficiency of this sub-receiver module reached 42.16% for 196 suns, which is a 7.41% boosted value compared to that of a module with bare coverglass, without any detrimental changes of the open circuit voltages (V(oc)) and fill factor (FF). PMID:23326839

  4. Enhanced power generation in concentrated photovoltaics using broadband antireflective coverglasses with moth eye structures.

    PubMed

    Song, Young Min; Jeong, Yonkil; Yeo, Chan Il; Lee, Yong Tak

    2012-11-01

    We present the effect of broadband antireflective coverglasses (BARCs) with moth eye structures on the power generation capability of a sub-receiver module for concentrated photovoltaics. The period and height of the moth eye structures were designed by a rigorous coupled-wave analysis method in order to cover the full solar spectral ranges without transmission band shrinkage. The BARCs with moth eye structures were prepared by the dry etching of silver (Ag) nanomasks, and the fabricated moth eye structures on coverglass showed strongly enhanced transmittance compared to the bare glass with a flat surface, at wavelengths of 300 - 1800 nm. The BARCs were mounted on InGaP/GaAs/Ge triple-junction solar cells and the power conversion efficiency of this sub-receiver module reached 42.16% for 196 suns, which is a 7.41% boosted value compared to that of a module with bare coverglass, without any detrimental changes of the open circuit voltages (Voc) and fill factor (FF). PMID:23187668

  5. Hierarchically porous micro/nanostructured copper surfaces with enhanced antireflection and hydrophobicity

    NASA Astrophysics Data System (ADS)

    Li, Ming; Su, Yanjie; Hu, Jing; Yao, Lu; Wei, Hao; Yang, Zhi; Zhang, Yafei

    2016-01-01

    A facile hydrothermal method has been proposed to fabricate hierarchically porous Cu micro/nanostructures on Cu foil, whose growth can be controlled by the reaction time and the amount of ethylene glycol added into the precursor. Compared to commercially available Cu foil, the micro/nanostructured Cu surfaces exhibit not only greatly enhanced ability to absorb light over a wide range of wavelengths from 250 to 1000 nm, but also improved hydrophobicity from 90.4° to 151.2° without any low-surface-energy chemical modification. The reflectance can reach a lowest value of 10% at 300 nm and show a biggest decrement of 53% at 582 nm. Due to their superhydrophobicity, the micro/nanostructured Cu foils demonstrate an improved anticorrosion ability against 3.5 wt% NaCl solution compared with a bare one. The proposed mechanism indicates that the combination of the dual-scale roughness and the adsorbed air in pores account for the enhanced antireflection and hydrophobicity.

  6. Low emittance, semi-transparent coating for cryogenic window applications

    NASA Astrophysics Data System (ADS)

    Heaney, James B.; Nowak, Maria; Quijada, Manuel; Threat, Felix; Stock, Joseph

    2009-08-01

    A warm window surface with a relatively high (>50%) surface emittance can add significant undesired heat loading into a cryogenic test chamber. However, a front surface coating that consists of a very thin adherent layer of evaporated Cr that is overcoated with about 7nm of evaporated Au has been demonstrated to reduce the inherently high emittance of a glass or sapphire window surface down to about 14%, while maintaining a visible transmittance in excess of 55%. The coating possesses reasonably good adhesion and cleaning durability when deposited onto glass or sapphire substrates and has survived multiple temperature cycles between 316K and 20K. The addition of a single layer anti-reflection coating, such as reactively evaporated SiOx, to the otherwise uncoated exterior surface of a cryogenic window produced a further increase in visible wavelength transmittance without altering window emittance. This paper will present measured reflectance, transmittance, and emittance data for the Cr + Au window surface coating relevant to a cryogenic window application.

  7. Vacuum deposited optical coatings experiment (AO 138-4)

    NASA Technical Reports Server (NTRS)

    Charlier, Jean

    1991-01-01

    The aim of this experiment was to test the optical behavior of 20 components and coatings subjected to space exposure. Most of them are commonly used for their reflective or transmittive properties in spaceborne optics. They consist in several kind of metallic and dielectric mirrors designed for the 0.12 to 10 microns spectrum, UV, and NIR bandpass filters, visible, and IR antireflecting coatings, visible/IR dichroic beam splitters, and visible beam splitter. The coatings were deposited on various substrates such as glasses, germanium, magnesium fluoride, quartz, zinc selenide, and kanigened aluminum. Several coating materials were used such as Al, Ag, Au, MgF2, LaF3, ThF3, ThF4, SiO2, TiO2, ZrO2, Al2O3, MgO, Ge, and ZnSe. Five samples of each component were manufactured. Two flight samples were mounted in such a way that one was directly exposed to space and the other looking backwards. The same arrangement was used for the spare samples stored on ground in a box identical to the flight one and they were kept under vacuum during the LDEF mission. Finally, one set of reference components was stocked in a sealed box under a dry nitrogen atmosphere. By comparing the preflight and postflight optical performances of the five samples of each component, it is possible to detect the degradations due to the space exposure.

  8. Coatings for high energy applications. The Nova laser

    SciTech Connect

    Wirtenson, G.R.

    1986-01-01

    The combined requirements of energy density, multiple wavelength, and aperture make the coatings for the Nova Inertial Confinement Fusion (ICF) laser unique. This ten beam neodymium glass laser system, built at the Lawrence Livermore National Laboratory (LLNL), has over a thousand major optical components; some larger than one meter in diameter and weighing 380 Kg. The laser operates at 1054 nm and can be frequency doubled to 527 nm or tripled to 351 nm by means of full aperture potassium dihydrogen phosphate (KDP) crystal arrays. The 1.0 nsec fluence varies along the laser chain, sometimes reaching values as high as 16 J/cm/sup 2/ at the input lens to one of the spatial filters. The design specifications of this massive optical system were changed several times as the state-of-the-art advanced. Each change required redesign of the optical coatings even as vendors were preparing for production runs. Frequency conversion to include shorter wavelengths mandated the first major coating redesign and was followed almost immediately by a second redesign to reduce solarization effects in borosilicate crown glass. The conventional thermal evaporation process although successful for the deposition of mirror coatings, was not able to produce antireflection coatings able to survive the locally high chain fluences. As a consequence it became necessary to develop another technique. Solution produced coatings were developed having transmissions exceeding 99% per part and damage threshold values equal to the bare substrate. The unique requirement of the Nova laser necessitated special deposition and metrology equipment. These programmatic developments will be reviewed in the context of the cooperative working relationship developed between LLNL and its vendors. It was this excellent relationship which has enabled LLNL to obtain these highly specialized coatings for the Nova laser.

  9. Diamond Coatings

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

  10. Optical coatings for high average power XeF lasers: Final report

    SciTech Connect

    Milam, D.; Thomas, I.; Wilder, J.; George, D.

    1988-03-16

    Porous silica, calcium and magnesium fluorides were investigated for potential use as antireflective coatings for XeF lasers. Excellent optical properties were obtained for all types, and laser damage thresholds were in the range 18-25 Jcm/sup 2/ at 350 nm for 25 ns pulses at 25 Hz pulse repetition frequency. Studies of the effects of the XeF laser environment on these coatings were incomplete. Three oxides, ZrO/sub 2/, HfO/sub 2/, and Ta/sub 2/O/sub 5/ were investigated as the high index components to be paired with low index porous SiO/sub 2/ for highly reflective dielectric coatings. Single oxide layers had indices in the 1.7-1.8 range and HfO/sub 2/ coatings had the highest damage threshold at about 5 Jcm/sup 2/. An unexpected problem arose on attempts to prepare multilayer coatings. Stress in the coating after 6-8 layers had been put down, gave rise to crazing and peeling. This could not be avoided even on extending the curing process between coats.

  11. Improving material-specific dispense processes for low-defect coatings

    NASA Astrophysics Data System (ADS)

    Smith, Brian; Ramirez, Raul; Braggin, Jennifer; Wu, Aiwen; Anderson, Karl; Berron, John; Brakensiek, Nick; Washburn, Carlton

    2010-04-01

    Minimizing defects in spin-on lithography coatings requires a careful understanding of the interactions between the spin-on coating material and the filtration and dispense system used on the coating track. A wet-developable bottom anti-reflective coating (BARC) was examined for its interaction with polyamide and UPE media when utilizing the Entegris IntelliGen Mini dispense system. In addition, a new method of priming the filter and pump is described which improves the wetting of the filter media, preventing bubbles and other defect-generating air pockets within the system. The goal is to establish plumb-on procedures that are material and hardware specific to avoid any defect problems in the coating process, as well as to gain a better understanding of the chemical and physical interactions that lead to coating defects. Liquid particle counts from a laboratory-based filtration stand are compared with on-wafer defects from a commercial coating track to establish a correlation and allow better prediction of product performance. This comparison in turn will provide valuable insight to the engineering process of product filtration and bottling at the source.

  12. Protective Coatings

    NASA Technical Reports Server (NTRS)

    1980-01-01

    General Magnaplate Corporation's pharmaceutical machine is used in the industry for high speed pressing of pills and capsules. Machine is automatic system for molding glycerine suppositories. These machines are typical of many types of drug production and packaging equipment whose metal parts are treated with space spinoff coatings that promote general machine efficiency and contribute to compliance with stringent federal sanitation codes for pharmaceutical manufacture. Collectively known as "synergistic" coatings, these dry lubricants are bonded to a variety of metals to form an extremely hard slippery surface with long lasting self lubrication. The coatings offer multiple advantages; they cannot chip, peel or be rubbed off. They protect machine parts from corrosion and wear longer, lowering maintenance cost and reduce undesired heat caused by power-robbing friction.

  13. Gold Coating

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Epner Technology Inc. responded to a need from Goddard Space Flight Center for the ultimate in electroplated reflectivity needed for the Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA). Made of beryllium, the MOLA mirror was coated by Epner Technology Laser Gold process, specially improved for the project. Improved Laser Gold- coated reflectors have found use in an epitaxial reactor built for a large semiconductor manufacturer as well as the waveguide in Braun-Thermoscan tympanic thermometer and lasing cavities in various surgical instruments.

  14. Photonic crystal based on anti-reflection structure for GaN/InGaN heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Ding, Wen; Xia, Deyang; Li, Qiang; Huang, Yaping; Zheng, Min; Zhang, Linzhao; Wang, Jin; Zhang, Ye; Guo, Maofeng; Liu, Shuo; Su, Xilin; Yun, Feng; Hou, Xun

    2015-02-01

    The III-V nitride material such as InGaN has many favorable physical properties including a wide direct band-gap (0.7- 3.4eV), high absorption coefficients (105 cm-1), and high radiation resistance. As such, InGaN has been chosen as an excellent material for full-solar-spectrum photovoltaic applications utilizing its wide and tunable band-gap. The refractive index of GaN is about 2.5 in the full-solar-spectrum. According to the Fresnel formula, there is a high reflection of ~18.4% as the sun light entering GaN. Anti-reflection films could be used on InGaN/GaN solar cell to decrease the reflection loss. The photonic crystal structure is a kind of anti-reflection based on the effective medium theory without any limitations, for example the mismatched thermal expansion coefficient. In this paper, we reported our research work on the design and fabrication of photonic crystal structure on the surface of GaN. FDTD Solutions is used to simulate the reflectivity on the surface of GaN with hexagonal close-packed pillar which has different period-a, diameter-d and height-h. When the parameters a is 500nm, d is 300nm, the reflectivity reached the lowest point of 4.18%. The self-assembly method was used to fabricate the photonic crystal structure on the GaN surface and the fabrication process was also researched. The photonic crystal structures on the surface of p-GaN were obtained and their characteristics of the antireflective film will be discussed in detail.

  15. Antireflective conducting nanostructures with an atomic layer deposited an AlZnO layer on a transparent substrate

    NASA Astrophysics Data System (ADS)

    Park, Hyun-Woo; Ji, Seungmuk; Herdini, Diptya Suci; Lim, Hyuneui; Park, Jin-Seong; Chung, Kwun-Bum

    2015-12-01

    The antireflective conducting nanostructures on a transparent substrate were shown to have enhanced optical and electrical properties via colloidal lithography and atomic layer deposition. The conformal AlZnO layer on a transparent nanostructured substrate exhibited 5.52 × 10-4 Ω cm in resistivity and 88% in average visible transmittance, both of which were superior to those of a flat transparent conducting substrate. The improvement of transparency was explained by the gradual changes of the refractive index in the film depth direction. The decrease in electrical resistivity is strongly correlated to the increased surface area with the nanostructure and the change of chemical bonding states.

  16. A two-in-one superhydrophobic and anti-reflective nanodevice in the grey cicada Cicada orni (Hemiptera)

    NASA Astrophysics Data System (ADS)

    Dellieu, Louis; Sarrazin, Michaël; Simonis, Priscilla; Deparis, Olivier; Vigneron, Jean Pol

    2014-07-01

    Two separated levels of functionality are identified in the nanostructure which covers the wings of the grey cicada Cicada orni (Hemiptera). The upper level is responsible for superhydrophobic character of the wing, while the lower level enhances its anti-reflective behavior. Extensive wetting experiments with various chemical species and optical measurements were performed in order to assess the bi-functionality. Scanning electron microscopy imaging was used to identify the nanostructure morphology. Numerical optical simulations and analytical wetting models were used to prove the roles of both levels of the nanostructure. In addition, the complex refractive index of the chitinous material of the wing was determined from measurements.

  17. A two-in-one superhydrophobic and anti-reflective nanodevice in the grey cicada Cicada orni (Hemiptera)

    SciTech Connect

    Dellieu, Louis Sarrazin, Michaël Simonis, Priscilla; Deparis, Olivier; Vigneron, Jean Pol

    2014-07-14

    Two separated levels of functionality are identified in the nanostructure which covers the wings of the grey cicada Cicada orni (Hemiptera). The upper level is responsible for superhydrophobic character of the wing, while the lower level enhances its anti-reflective behavior. Extensive wetting experiments with various chemical species and optical measurements were performed in order to assess the bi-functionality. Scanning electron microscopy imaging was used to identify the nanostructure morphology. Numerical optical simulations and analytical wetting models were used to prove the roles of both levels of the nanostructure. In addition, the complex refractive index of the chitinous material of the wing was determined from measurements.

  18. Fabrication of hierarchical anti-reflective structures using polystyrene sphere lithography on an as-cut p-Si substrate

    NASA Astrophysics Data System (ADS)

    Chou, Yen-Yu; Lee, Kuan-Tao; Lee, Yeeu-Chang

    2016-07-01

    The broadband anti-reflective (AR) properties of hierarchical structures (HSs) have attracted considerable attention in recent years as a means to reduce Fresnel reflection in photovoltaic solar cell materials. This study employed polystyrene sphere lithography in conjunction with high density plasma dry etching in the fabrication of pure sub-wavelength structures and HSs on an as-cut p-Si substrate. Etching parameters, such as RF power, O2, and etching time, were adjusted to alter the surface morphology. Experiment results demonstrate that the resulting hierarchical paraboloidal structures suppress average reflectance to below 0.5% across a spectral range of 500-1000 nm.

  19. Modeling the absorption behavior of solar thermal collector coatings utilizing graded alpha-C:H/TiC layers.

    PubMed

    Gruber, D P; Engel, G; Sormann, H; Schüler, A; Papousek, W

    2009-03-10

    Wavelength selective coatings are of common use in order to enhance the efficiency of devices heated by radiation such as solar thermal collectors. The use of suitable materials and the optimization of coating layer thicknesses are advisable ways to maximize the absorption. Further improvement is achievable by embedding particles in certain layers in order to modify material properties. We focus on optimizing the absorption behavior of a solar collector setup using copper as substrate, a layer of amorphous hydrogenated carbon with embedded titanium carbide particles (a-C:H/TiC), and an antireflection coating of amorphous silicon dioxide (aSiO(2)). For the setup utilizing homogeneous particle distribution, a relative absorption of 90.98% was found, while inhomogeneous particle embedding yielded 98.29%. These results are particularly interesting since until now, absorption of more than 95% was found only by using embedded Cr but not by using the more biocompatible Ti. PMID:19277084

  20. High-performance broadband optical coatings on InGaN/GaN solar cells for multijunction device integration

    SciTech Connect

    Young, N. G. Farrell, R. M.; Iza, M.; Speck, J. S.; Perl, E. E.; Keller, S.; Bowers, J. E.; Nakamura, S.; DenBaars, S. P.

    2014-04-21

    We demonstrate InGaN/GaN multiple quantum well solar cells grown by metalorganic chemical vapor deposition on a bulk (0001) substrate with high-performance broadband optical coatings to improve light absorption. A front-side anti-reflective coating and a back-side dichroic mirror were designed to minimize front surface reflections across a broad spectral range and maximize rear surface reflections only in the spectral range absorbed by the InGaN, making the cells suitable for multijunction solar cell integration. Application of optical coatings increased the peak external quantum efficiency by 56% (relative) and conversion efficiency by 37.5% (relative) under 1 sun AM0 equivalent illumination.

  1. [beta]-silicon carbide protective coating and method for fabricating same

    DOEpatents

    Carey, P.G.; Thompson, J.B.

    1994-11-01

    A polycrystalline beta-silicon carbide film or coating and method for forming same on components, such as the top of solar cells, to act as an extremely hard protective surface, and as an anti-reflective coating are disclosed. This is achieved by DC magnetron co-sputtering of amorphous silicon and carbon to form a SiC thin film onto a surface, such as a solar cell. The thin film is then irradiated by a pulsed energy source, such as an excimer laser, to synthesize the poly- or [mu]c-SiC film on the surface and produce [beta]-SiC. While the method of this invention has primary application in solar cell manufacturing, it has application wherever there is a requirement for an extremely hard surface. 3 figs.

  2. .beta.-silicon carbide protective coating and method for fabricating same

    DOEpatents

    Carey, Paul G.; Thompson, Jesse B.

    1994-01-01

    A polycrystalline beta-silicon carbide film or coating and method for forming same on components, such as the top of solar cells, to act as an extremely hard protective surface, and as an anti-reflective coating. This is achieved by DC magnetron co-sputtering of amorphous silicon and carbon to form a SiC thin film onto a surface, such as a solar cell. The thin film is then irradiated by a pulsed energy source, such as an excimer laser, to synthesize the poly- or .mu.c-SiC film on the surface and produce .beta.--SiC. While the method of this invention has primary application in solar cell manufacturing, it has application wherever there is a requirement for an extremely hard surface.

  3. Optimization of textured-dielectric coatings for crystalline-silicon solar cells

    SciTech Connect

    Gee, J.M.; Gordon, R.; Liang, H.

    1996-07-01

    The authors report on the optimization of textured-dielectric coatings for reflectance control in crystalline-silicon (c-Si) photovoltaic modules. Textured-dielectric coatings reduce encapsulated-cell reflectance by promoting optical confinement in the module encapsulation; i.e., the textured-dielectric coating randomizes the direction of rays reflected from the dielectric and from the c-Si cell so that many of these reflected rays experience total internal reflection at the glass-air interface. Some important results of this work include the following: the authors demonstrated textured-dielectric coatings (ZnO) deposited by a high-throughput low-cost deposition process; they identified factors important for achieving necessary texture dimensions; they achieved solar-weighted extrinsic reflectances as low as 6% for encapsulated c-Si wafers with optimized textured-ZnO coatings; and they demonstrated improvements in encapsulated cell performance of up to 0.5% absolute compared to encapsulated planar cells with single-layer antireflection coatings.

  4. Engine Coatings

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Increasing the operating temperature of turbine engines reduces fuel consumption and increases engine efficiency. However, engine components must be protected from excessive heat. Lewis Research Center has successfully developed thermal barrier coatings (TBCs), which are deposited on the components. They insulate, offer oxidation and corrosion resistance and increase adherence. Surface temperatures can be reduced by 200 degrees centigrade or more. G. E. Aircraft Engines, a Lewis contractor, now uses a TBC based on the one developed at Lewis, on production engines. The system, which consists of a bond and a top coat extends component life from 1.3 to 2 times. The company is also testing TBCs on components that operate at higher temperatures.

  5. Abrasion-resistant solgel antireflective films with a high laser-induced damage threshold for inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Xu, Yao; Zhang, Lei; Wu, Dong; Sun, Yu Han; Huang, Zu Xing; Jiang, Xiao Dong; Wei, Xiao Feng; Li, Zhi Hong; Dong, Bao Zhong; Wu, Zhong Hua

    2005-09-01

    To prepare abrasion-resistant antireflective (AR) films for inertial confinement fusion, four solgel routes have been investigated on polysiloxane-modified and polyvinylalcohol- (PVA-) modified SiO2 sols. As confirmed with a transmissive electron microscope, different fractal structure characteristics of the modified SiO2 particles are disclosed by small-angle x-ray scattering technology. And it is these special fractal characteristics that determine the performance of AR films on the level of internal microstructure. A 29Si magic angle spinning and nuclear magnetic resonance study has been successfully applied in explaining the fractal microstructure and its relation to the laser-induced damage threshold (LIDT) of AR films. The films modified by PVA120000 or acetic acid-catalyzed polysiloxane have higher LIDTs than those films modified by PVA16000 or hydrochloride acid-catalyzed polysiloxane. The films from PVA-modified SiO2 sols have a stronger abrasion resistance but lower antireflection than those films from polysiloxane-modified SiO2 sols. In addition, the films from polysiloxane-modified SiO2 sols can possess high transmittance and high LIDT if the polysiloxane synthesis condition is appropriately chosen, but the abrasion resistance is not as good as that from PVA modification. If strong abrasion resistance is necessary, a possible resolution may be to choose a more appropriate hydrophilic polymer than PVA. If not, polysiloxane-modified silica sol can also work when polysiloxane is synthesized under acetic acid catalysis.

  6. COATING METHOD

    DOEpatents

    Townsend, R.G.

    1959-08-25

    A method is described for protectively coating beryllium metal by etching the metal in an acid bath, immersing the etched beryllium in a solution of sodium zincate for a brief period of time, immersing the beryllium in concentrated nitric acid, immersing the beryhlium in a second solution of sodium zincate, electroplating a thin layer of copper over the beryllium, and finally electroplating a layer of chromium over the copper layer.

  7. Nickel-oxide film as an AR coating of Si window for IR sensor packaging

    NASA Astrophysics Data System (ADS)

    Shim, Hyunbin; Kim, Dongsoo; Kang, Ingu; Kim, Jinkwan; Lee, Hee Chul

    2013-06-01

    An infrared (IR) transparent window is necessary for the IR sensor package. The most commonly used materials for IR transparent window are germanium (Ge) and silicon (Si). Ge has excellent optical properties but also the disadvantage of expensive price. Si has merits such as inexpensive cost and CMOS process compatibility but it has lower transmittance in the range of LWIR region than Ge. Therefore, an alternative anti-reflection (AR) coating is necessary to increase the transmittance of Si as an IR transparent window in the LWIR region. A simple single layer antireflection coating was newly designed on the silicon window for the infrared sensor package. Among the various materials, nickel oxide (NiO) was selected as an AR coating material due to its suitable optical properties and simple process. NiO film was deposited onto the double sided polished Si wafer by reactive rf sputtering with Ni target in an environment of Ar and O2 mixed gas. The thickness of the NiO film was determined by Essential Macleod simulation. FT-IR was used to measure the transmittance of the samples in the LWIR region. After the nickel oxide film was sputtered onto the double sides of the silicon wafer, the measured transmittance of the Si wafer was increased over 20% in the LWIR region compared with that of uncoated Si wafer. Additionally, annealing effect on the transmittance of NiO coated Si wafer was studied. By increasing the annealing temperature from 300° to 700°, an additional increase of transmittance was achieved.

  8. Optical Properties of Nanostructured Dielectric Coatings

    NASA Astrophysics Data System (ADS)

    Giatti, Brandon

    Solar cells have extrinsic losses from a variety of sources which can be minimized by optimization of the design and fabrication processes. Reflection from the front surface is one such loss mechanism and has been managed in the past with the usage of planar antireflection coatings. While effective, these coatings are each limited to a single wavelength of light and do not account for varying incident angles of the incoming light source. Three-dimensional nanostructures have shown the ability to inhibit reflection for differing wavelengths and angles of incidence. Nanocones were modeled and show a broadband, multi-angled reflectance decrease due to an effective grading of the index. Finite element models were created to simulate incident light on a zinc oxide nanocone textured silicon substrate. Zinc oxide is advantageous for its ease of production, benign nature, and refractive index matching to the air source region and silicon substrate. Reflectance plots were computed as functions of incident angle and wavelength of light and compared with planar and quintic refractive index profile models. The quintic profile model exhibits nearly optimum reflection minimization and is thus used as a benchmark. Physical quantities, including height, width, density, and orientation were varied in order to minimize the reflectance. A quasi-random nanocone unit cell was modeled to better mimic laboratory results. The model was comprised of 10 nanocones with differing structure and simulated a larger substrate by usage of periodic boundary conditions. The simulated reflectance shows approximately a 50 percent decrease when compared with a planar model. When a seed layer is added, simulating a layer of non-textured zinc oxide, on which the nanocones are grown, the reflectance shows a fourfold decrease when compared with planar models. At angles of incidence higher than 75 degrees, the nanocone model outperformed the quintic model.

  9. Transparent and Dense Ladder-Like Alkylene-Bridged Polymethylsiloxane Coating with Enhanced Water Vapor Barrier Property.

    PubMed

    Zhang, Ce; Zhang, Cong; Cui, Xinmin; Sun, Jinghua; Ding, Ruimin; Zhang, Qinghua; Xu, Yao

    2015-10-14

    Organic-inorganic hybrid composites have been well-studied as water vapor barrier materials for their long diffusion length of water vapor in coatings which can be realized by improving the aspect ratio of inorganic components and regularity of nanostructure in coatings. In this paper, dense organic-inorganic hybrid coating based on ladder-like alkylene-bridged polymethylsiloxane (ABPMS) was successfully fabricated through the hydrosilylation reaction between polymethylhydrosiloxane and diene (1,5-hexadiene or 1,7-octadiene) in toluene under Pt/C catalysis. Its ladder-like structure was verified by 29Si magic angle spinning (MAS) NMR, 13C MAS NMR, and in-plane and out-of-plane glance-incident X-ray diffraction (GIXRD) techniques. Its corresponding coating showed excellent water vapor barrier ability for a typical water-soluble crystal, potassium dihydrogen phosphate (KDP). When treated in 50% relative humidity (RH) condition at 25 °C for 8 months, the ABPMS coating with 100 nm thickness displayed a very low transmittance loss of 1.6% compared with the high transmittance loss of 10% for uncoated KDP. Moreover, the ABPMS coating showed good ultraviolet radiation resistance, thermal stability, low mechanical property, and excellent compatibility with hydrophobic antireflective (AR) coatings. PMID:26393288

  10. NICKEL COATED URANIUM ARTICLE

    DOEpatents

    Gray, A.G.

    1958-10-01

    Nickel coatings on uranium and various methods of obtaining such coatings are described. Specifically disclosed are such nickel or nickel alloy layers as barriers between uranium and aluminum- silicon, chromium, or copper coatings.

  11. Corrosion resistant coating

    DOEpatents

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  12. Corrosion resistant coating

    DOEpatents

    Wrobleski, D.A.; Benicewicz, B.C.; Thompson, K.G.; Bryan, C.J.

    1997-08-19

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  13. Optical simulations for fractional fluorine terminated coatings on nanoimprint lithography masks

    NASA Astrophysics Data System (ADS)

    Seidel, Thomas E.; Goldberg, Alexander; Halls, Mathew D.

    2015-10-01

    Simulations of the optical intensity within Nano Imprint Lithography (NIL) mask features have been made for patterned quartz masks having ultrathin film coatings with different indices of refraction. Fractionally fluorine terminated surfaces, previously proposed for improving the yield of NIL processes, are briefly reviewed. Optical intensity solutions within the feature were obtained using Panoramictech Maxwell solver software for variances in the optical constants of the coating films, aspect ratio, feature size, and wavelength.. The coated masks have conformal surface, higher index of refraction under-layer coating and a fractional terminated fluorine hydrocarbon (FHC) monomolecular layer. The values of optical constants for the FHC layers are unknown, so a range of ad-hoc values were simulated. Optical constants for quartz mask and Al2O3, TiO2 and Si under-layer films are taken from the literature. Wavelengths were varied from 193nm to 365nm. The question of photo-dissociation of the FHC layer for higher energy photons is addressed from first principles, with the result that the F-terminated layers are stable at higher wavelengths. Preliminary simulations for features filled with resist over various substrates are dependent on the antireflection character of the underlying film system. The optical intensity is generally increased within the simulated mask feature when coated with a higher index/FHC films relative to the uncoated reference quartz mask for ~5nm physical feature sizes.

  14. Reactive ion-beam-sputtering of fluoride coatings for the UV/VUV range

    NASA Astrophysics Data System (ADS)

    Schink, Harald; Kolbe, Jurgen; Zimmermann, F.; Ristau, Detlev; Welling, Herbert

    1991-06-01

    Fluoride coatings produced by thermal evaporation suffer from high scatter losses ageing and cracking due to high tensile stress. These problems impose severe limitations to the production of low loss multilayer coatings for the VUV range. A key position for improved performance is the microstructure of the layers. The aim of our investigations is to improve the microstructure of A1F3- and LaF3-'' films by ionbeamsputtering. Scatter measurements of single layers revealed lower values for lBS than for boat evaporation. Unfortunately sputtered fluoride films nave high absorption losses caused by decomposition of the coating material. By sputtering in reactive atmospheres and annealing we were able to reduce the absorption losses significantly. Antireflective as well as high reflective coatings were produced. Reflection and transmission values were obtained with a VUV-spectrophotometer. Damage tests at the 193 mu ArF laser wavelength were performed at the Laser-Laboratorium Gttingen. Key words: ion-beamsputtering fluoride films UVcoatings VUV-coatings color-center laser damage A]. F3 MgF2 LaF3. 1.

  15. Study of barrier coats for application in immersion 193-nm lithography

    NASA Astrophysics Data System (ADS)

    Houlihan, Francis; Kim, Wookyu; Sakamuri, Raj; Hamilton, Keino; Dimerli, Alla; Abdallah, David; Romano, Andrew; Dammel, Ralph R.; Pawlowski, Georg; Raub, Alex; Brueck, Steve

    2005-05-01

    We will describe our barrier coat approach for use in immersion 193 nm lithography. These barrier coats may act as either simple barriers providing protection against loss of resist components into water or in the case of one type of these formulations which have a refractive index at 193 nm which is the geometric mean between that of the resist and water provide, also top antireflective properties. Either type of barrier coat can be applied with a simple spinning process compatible with PGMEA based resin employing standard solvents such as alcohols and be removed during the usual resist development process with aqueous 0.26 N TMAH. We will discuss both imaging results with these materials on acrylate type 193 nm resists and also show some fundamental studies we have done to understand the function of the barrier coat and the role of differing spinning solvents and resins. We will show LS (55 nm) and Contact Hole (80 nm) resolved with a 193 nm resist exposed with the interferometric tool at the University of New Mexico (213 nm) with and without the use of a barrier coat.

  16. The Chemistry of Coatings.

    ERIC Educational Resources Information Center

    Griffith, James R.

    1981-01-01

    The properties of natural and synthetic polymeric "coatings" are reviewed, including examples and uses of such coatings as cellulose nitrate lacquers (for automobile paints), polyethylene, and others. (JN)

  17. Abrasion-resistant solgel antireflective films with a high laser-induced damage threshold for inertial confinement fusion

    SciTech Connect

    Xu Yao; Zhang Lei; Wu Dong; Sun Yu Han; Huang Zuxing; Jiang Xiaodong; Wei Xiaofeng; Li Zhihong; Dong Baozhong; Wu Zhonghua

    2005-09-01

    To prepare abrasion-resistant antireflective (AR) films for inertial confinement fusion, four solgel routes have been investigated on polysiloxane-modified and polyvinylalcohol- (PVA-) modified SiO{sub 2} sols. As confirmed with a transmissive electron microscope, different fractal structure characteristics of the modified SiO{sub 2} particles are disclosed by small-angle x-ray scattering technology. And it is these special fractal characteristics that determine the performance of AR films on the level of internal microstructure. A {sup 29}Si magic angle spinning and nuclear magnetic resonance study has been successfully applied in explaining the fractal microstructure and its relation to the laser-induced damage threshold (LIDT) of AR films. The films modified by PVA120000 or acetic acid-catalyzed polysiloxane have higher LIDTs than those films modified by PVA16000 or hydrochloride acid-catalyzed polysiloxane. The films from PVA-modified SiO{sub 2} sols have a stronger abrasion resistance but lower antireflection than those films from polysiloxane-modified SiO{sub 2} sols. In addition, the films from polysiloxane-modified SiO{sub 2} sols can possess high transmittance and high LIDT if the polysiloxane synthesis condition is appropriately chosen, but the abrasion resistance is not as good as that from PVA modification. If strong abrasion resistance is necessary, a possible resolution may be to choose a more appropriate hydrophilic polymer than PVA. If not, polysiloxane-modified silica sol can also work when polysiloxane is synthesized under acetic acid catalysis.

  18. Spectral reflectance data of a high temperature stable solar selective coating based on MoSi2 -Si3N4.

    PubMed

    Hernández-Pinilla, D; Rodríguez-Palomo, A; Álvarez-Fraga, L; Céspedes, E; Prieto, J E; Muñoz-Martín, A; Prieto, C

    2016-06-01

    Data of optical performance, thermal stability and ageing are given for solar selective coatings (SSC) based on a novel MoSi2-Si3N4 absorbing composite. SSC have been prepared as multilayer stacks formed by silver as metallic infrared reflector, a double layer composite and an antireflective layer (doi: 10.1016/j.solmat.2016.04.001 [1]). Spectroscopic reflectance data corresponding to the optical performance of samples after moderate vacuum annealing at temperatures up to 600 °C and after ageing test of more than 200 h with several heating-cooling cycles are shown here. PMID:27182544

  19. Spectral reflectance data of a high temperature stable solar selective coating based on MoSi2–Si3N4

    PubMed Central

    Hernández-Pinilla, D.; Rodríguez-Palomo, A.; Álvarez-Fraga, L.; Céspedes, E.; Prieto, J.E.; Muñoz-Martín, A.; Prieto, C.

    2016-01-01

    Data of optical performance, thermal stability and ageing are given for solar selective coatings (SSC) based on a novel MoSi2–Si3N4 absorbing composite. SSC have been prepared as multilayer stacks formed by silver as metallic infrared reflector, a double layer composite and an antireflective layer (doi: 10.1016/j.solmat.2016.04.001 [1]). Spectroscopic reflectance data corresponding to the optical performance of samples after moderate vacuum annealing at temperatures up to 600 °C and after ageing test of more than 200 h with several heating–cooling cycles are shown here. PMID:27182544

  20. Excellent anti-fogging dye-sensitized solar cells based on superhydrophilic nanoparticle coatings

    NASA Astrophysics Data System (ADS)

    Park, Jung Tae; Kim, Jong Hak; Lee, Daeyeon

    2014-06-01

    We present a facile method for producing anti-fogging (AF) and anti-reflection (AR) coating functionalized photoanodes via one-step SiO2 nanoparticle coating for high performance solid state dye-sensitized solar cells (ssDSSCs). The AF and AR coating functionalized photoanodes are prepared by spin-coating of partially aggregated SiO2 colloidal solution. Poly((1-(4-ethenylphenyl)methyl)-3-butyl-imidazolium iodide) (PEBII), prepared via free radical polymerization, is used as a solid electrolyte in I2-free ssDSSCs. We systematically investigate the enhanced light harvesting characteristics of AF and AR coating functionalized photoanode-based ssDSSCs by measuring UV-visible spectroscopy, incident photon-to-electron conversion efficiency (IPCE) curves under fogging conditions. Compared with conventional photoanode based ssDSSCs, the AF and AR coating functionalized photoanodes substantially suppress fogging and reduce reflection, leading to significantly enhanced light harvesting, especially under fogging conditions. ssDSSCs made of AF and AR coating functionalized photoanodes exhibit an improved photovoltaic efficiency of 6.0% and 5.9% under non-fogging and fogging conditions, respectively, and retain their device efficiencies for at least 20 days, which is a significant improvement of ssDSSCs with conventional photoanodes (4.7% and 1.9% under non-fogging and fogging conditions, respectively). We believe that AF and AR functionalization via one-step SiO2 colloidal coating is a promising method for enhancing light harvesting properties in various solar energy conversion applications.We present a facile method for producing anti-fogging (AF) and anti-reflection (AR) coating functionalized photoanodes via one-step SiO2 nanoparticle coating for high performance solid state dye-sensitized solar cells (ssDSSCs). The AF and AR coating functionalized photoanodes are prepared by spin-coating of partially aggregated SiO2 colloidal solution. Poly((1-(4-ethenylphenyl)methyl)-3