Semiconductor ferroelectric compositions and their use in photovoltaic devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rappe, Andrew M; Davies, Peter K; Spanier, Jonathan E

Disclosed herein are ferroelectric perovskites characterized as having a band gap, Egap, of less than 2.5 eV. Also disclosed are compounds comprising a solid solution of KNbO3 and BaNi1/2Nb1/2O3-delta, wherein delta is in the range of from 0 to about 1. The specification also discloses photovoltaic devices comprising one or more solar absorbing layers, wherein at least one of the solar absorbing layers comprises a semiconducting ferroelectric layer. Finally, this patent application provides solar cell, comprising: a heterojunction of n- and p-type semiconductors characterized as comprising an interface layer disposed between the n- and p-type semiconductors, the interface layer comprisingmore » a semiconducting ferroelectric absorber layer capable of enhancing light absorption and carrier separation.« less

Low temperature thin films formed from nanocrystal precursors

DOEpatents

Alivisatos, A. Paul; Goldstein, Avery N.

1993-01-01

Nanocrystals of semiconductor compounds are produced. When they are applied as a contiguous layer onto a substrate and heated they fuse into a continuous layer at temperatures as much as 250, 500, 750 or even 1000.degree. K below their bulk melting point. This allows continuous semiconductor films in the 0.25 to 25 nm thickness range to be formed with minimal thermal exposure.

Low temperature thin films formed from nanocrystal precursors

DOEpatents

Alivisatos, A.P.; Goldstein, A.N.

1993-11-16

Nanocrystals of semiconductor compounds are produced. When they are applied as a contiguous layer onto a substrate and heated they fuse into a continuous layer at temperatures as much as 250, 500, 750 or even 1000 K below their bulk melting point. This allows continuous semiconductor films in the 0.25 to 25 nm thickness range to be formed with minimal thermal exposure. 9 figures.

Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

DOEpatents

Spahn, O.B.; Lear, K.L.

1998-03-10

The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g., Al{sub 2}O{sub 3}), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3--1.6 {mu}m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation. 10 figs.

Method for forming silver-copper mixed kesterite semiconductor film

DOEpatents

Gershon, Talia S.; Gunawan, Oki; Lee, Yun S.; Mankad, Ravin

2018-01-23

After forming a layer of a Cu-deficient kesterite compound having the formula Cu.sub.2-xZn.sub.1+xSn(S.sub.ySe.sub.1-y).sub.4, wherein 0

Substrate solder barriers for semiconductor epilayer growth

DOEpatents

Drummond, Timothy J.; Ginley, David S.; Zipperian, Thomas E.

1989-01-01

During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

Substrate solder barriers for semiconductor epilayer growth

DOEpatents

Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

1989-05-09

During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

Substrate solder barriers for semiconductor epilayer growth

DOEpatents

Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

1987-10-23

During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In molecular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating. 1 tab.

Liquid phase epitaxy of binary III–V nanocrystals in thin Si layers triggered by ion implantation and flash lamp annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wutzler, Rene, E-mail: r.wutzler@hzdr.de; Rebohle, Lars; Prucnal, Slawomir

2015-05-07

The integration of III–V compound semiconductors in Si is a crucial step towards faster and smaller devices in future technologies. In this work, we investigate the formation process of III–V compound semiconductor nanocrystals, namely, GaAs, GaSb, and InP, by ion implantation and sub-second flash lamp annealing in a SiO{sub 2}/Si/SiO{sub 2} layer stack on Si grown by plasma-enhanced chemical vapor deposition. Raman spectroscopy, Rutherford Backscattering spectrometry, and transmission electron microscopy were performed to identify the structural and optical properties of these structures. Raman spectra of the nanocomposites show typical phonon modes of the compound semiconductors. The formation process of themore » III–V compounds is found to be based on liquid phase epitaxy, and the model is extended to the case of an amorphous matrix without an epitaxial template from a Si substrate. It is shown that the particular segregation and diffusion coefficients of the implanted group-III and group-V ions in molten Si significantly determine the final appearance of the nanostructure and thus their suitability for potential applications.« less

Methods for improved growth of group III nitride semiconductor compounds

DOEpatents

Melnik, Yuriy; Chen, Lu; Kojiri, Hidehiro

2015-03-17

Methods are disclosed for growing group III-nitride semiconductor compounds with advanced buffer layer technique. In an embodiment, a method includes providing a suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. The method includes forming an AlN buffer layer by flowing an ammonia gas into a growth zone of the processing chamber, flowing an aluminum halide containing precursor to the growth zone and at the same time flowing additional hydrogen halide or halogen gas into the growth zone of the processing chamber. The additional hydrogen halide or halogen gas that is flowed into the growth zone during buffer layer deposition suppresses homogeneous AlN particle formation. The hydrogen halide or halogen gas may continue flowing for a time period while the flow of the aluminum halide containing precursor is turned off.

Transparent contacts for stacked compound photovoltaic cells

DOEpatents

Tauke-Pedretti, Anna; Cederberg, Jeffrey; Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose Luis

2016-11-29

A microsystems-enabled multi-junction photovoltaic (MEM-PV) cell includes a first photovoltaic cell having a first junction, the first photovoltaic cell including a first semiconductor material employed to form the first junction, the first semiconductor material having a first bandgap. The MEM-PV cell also includes a second photovoltaic cell comprising a second junction. The second photovoltaic cell comprises a second semiconductor material employed to form the second junction, the second semiconductor material having a second bandgap that is less than the first bandgap, the second photovoltaic cell further comprising a first contact layer disposed between the first junction of the first photovoltaic cell and the second junction of the second photovoltaic cell, the first contact layer composed of a third semiconductor material having a third bandgap, the third bandgap being greater than or equal to the first bandgap.

Mechanical scriber for semiconductor devices

DOEpatents

Lin, Peter T.

1985-01-01

A mechanical scriber using a scribing tip, such as a diamond, provides controlled scriber forces with a spring-loaded compound lever arrangement. The scribing force and range of scribing depth are adjusted by a pair of adjustable micrometer heads. A semiconductor device, such as a multilayer solar cell, can be formed into scribed strips at each layer.

Low-Resistivity Zinc Selenide for Heterojunctions

NASA Technical Reports Server (NTRS)

Stirn, R. J.

1986-01-01

Magnetron reactive sputtering enables doping of this semiconductor. Proposed method of reactive sputtering combined with doping shows potential for yielding low-resistivity zinc selenide films. Zinc selenide attractive material for forming heterojunctions with other semiconductor compounds as zinc phosphide, cadmium telluride, and gallium arsenide. Semiconductor junctions promising for future optoelectronic devices, including solar cells and electroluminescent displays. Resistivities of zinc selenide layers deposited by evaporation or chemical vapor deposition too high to form practical heterojunctions.

Novel engineered compound semiconductor heterostructures for advanced electronics applications

NASA Astrophysics Data System (ADS)

Stillman, Gregory E.; Holonyak, Nick, Jr.; Coleman, James J.

1992-06-01

To provide the technology base that will enable SDIO capitalization on the performance advantages offered through novel engineered multiple-lavered compound semiconductor structures, this project has focussed on three specific areas: (1) carbon doping of AlGaAs/GaAs and InP/InGaAs materials for reliable high frequency heterojunction bipolar transistors; (2) impurity induced layer disordering and the environmental degradation of AlxGal-xAs-GaAs quantum-well heterostructures and the native oxide stabilization of AlxGal-xAs-GaAs quantum well heterostructure lasers; and (3) non-planar and strained-layer quantum well heterostructure lasers and laser arrays. The accomplishments in this three year research are reported in fifty-six publications and the abstracts included in this report.

Mechanical scriber for semiconductor devices

DOEpatents

Lin, P.T.

1985-03-05

A mechanical scriber using a scribing tip, such as a diamond, provides controlled scriber forces with a spring-loaded compound lever arrangement. The scribing force and range of scribing depth are adjusted by a pair of adjustable micrometer heads. A semiconductor device, such as a multilayer solar cell, can be formed into scribed strips at each layer. 5 figs.

Structural and electronic properties of the V-V compounds isoelectronic to GaN and isostructural to gray arsenic

NASA Astrophysics Data System (ADS)

Yang, Zhao; Han, Dan; Chen, Guohong; Chen, Shiyou

2018-03-01

The III-V binary compound semiconductors such as GaN, GaP, InN and InP have extensive applications in various optoelectronic, microwave and power-electronic devices. Using first-principles calculation, we systematically studied the structural and electronic properties of the V-V binary compounds (BiN, BiP, SbN and SbP) that are isoelectronic to GaN, GaP, InN and InP if Bi and Sb are in the +3 valence state. Interestingly, we found that the ground-state structures of BiP, SbN and SbP have the R-3m symmetry and are isostructural to the layered structure of gray arsenic, whereas BiN prefers a different ground-state structure with the C2 symmetry. Electronic structure calculations showed that the bulk BiN is a narrow bandgap semiconductor for its bandgap is about 0.2 eV. In contrast, BiP, SbN and SbP are metallic. The layered ground-state structure of the V-V binary compounds motivates us to study the electronic properties of their few-layer structures. As the structure becomes monolayer, their bandgaps increase significantly and are all in the range from about 1 eV to 1.7 eV, which are comparative to the bandgap of the monolayer gray arsenic. The monolayer BiP, SbN and SbP have indirect bandgaps, and they show a semiconductor-metal transition as the number of layers increase. Interestingly, the monolayer BiP has the largest splitting (350 meV) of the CBM valley, and thus may have potential application in novel spintronics and valleytronics devices.

Optical XOR gate

DOEpatents

Vawter, G. Allen

2013-11-12

An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Optical NOR gate

DOEpatents

Skogen, Erik J [Albuquerque, NM; Tauke-Pedretti, Anna [Albuquerque, NM

2011-09-06

An optical NOR gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical NOR gate utilizes two digital optical inputs and a continuous light input to provide a NOR function digital optical output. The optical NOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Prediction of weak topological insulators in layered semiconductors.

PubMed

Yan, Binghai; Müchler, Lukas; Felser, Claudia

2012-09-14

We report the discovery of weak topological insulators by ab initio calculations in a honeycomb lattice. We propose a structure with an odd number of layers in the primitive unit cell as a prerequisite for forming weak topological insulators. Here, the single-layered KHgSb is the most suitable candidate for its large bulk energy gap of 0.24 eV. Its side surface hosts metallic surface states, forming two anisotropic Dirac cones. Although the stacking of even-layered structures leads to trivial insulators, the structures can host a quantum spin Hall layer with a large bulk gap, if an additional single layer exists as a stacking fault in the crystal. The reported honeycomb compounds can serve as prototypes to aid in the finding of new weak topological insulators in layered small-gap semiconductors.

Fabrication of ionic liquid electrodeposited Cu--Sn--Zn--S--Se thin films and method of making

DOEpatents

Bhattacharya, Raghu Nath

2016-01-12

A semiconductor thin-film and method for producing a semiconductor thin-films comprising a metallic salt, an ionic compound in a non-aqueous solution mixed with a solvent and processing the stacked layer in chalcogen that results in a CZTS/CZTSS thin films that may be deposited on a substrate is disclosed.

Infrared emitting device and method

DOEpatents

Kurtz, S.R.; Biefeld, R.M.; Dawson, L.R.; Howard, A.J.; Baucom, K.C.

1997-04-29

The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region. Examples have been set forth showing embodiments of the present invention as surface- and edge-emitting light emitting diodes (LEDs), an optically-pumped semiconductor laser, and an electrically-injected semiconductor diode laser. The light emission from each of the infrared emitting devices of the present invention is in the midwave infrared region of the spectrum from about 2 to 6 microns. 8 figs.

Strain-compensated infrared photodetector and photodetector array

DOEpatents

Kim, Jin K; Hawkins, Samuel D; Klem, John F; Cich, Michael J

2013-05-28

A photodetector is disclosed for the detection of infrared light with a long cutoff wavelength in the range of about 4.5-10 microns. The photodetector, which can be formed on a semiconductor substrate as an nBn device, has a light absorbing region which includes InAsSb light-absorbing layers and tensile-strained layers interspersed between the InAsSb light-absorbing layers. The tensile-strained layers can be formed from GaAs, InAs, InGaAs or a combination of these III-V compound semiconductor materials. A barrier layer in the photodetector can be formed from AlAsSb or AlGaAsSb; and a contact layer in the photodetector can be formed from InAs, GaSb or InAsSb. The photodetector is useful as an individual device, or to form a focal plane array.

Feasibilty analyses of electroepitaxial research and development accommodations. Volume 2: Electroepitaxial growth of GaAs

NASA Technical Reports Server (NTRS)

1982-01-01

The technique of electromigration, i.e., electric field induced forced convection, can be used to grow semiconductor material and other compounds from solution by passing electric current through the growth interface while the temperature of the system is maintained constant. Current controlled electromigration, referred to as electroepitaxy, was successfully applied to grow epitaxial layers of various semiconductors and garnets.

A lead-halide perovskite molecular ferroelectric semiconductor

PubMed Central

Liao, Wei-Qiang; Zhang, Yi; Hu, Chun-Li; Mao, Jiang-Gao; Ye, Heng-Yun; Li, Peng-Fei; Huang, Songping D.; Xiong, Ren-Gen

2015-01-01

Inorganic semiconductor ferroelectrics such as BiFeO3 have shown great potential in photovoltaic and other applications. Currently, semiconducting properties and the corresponding application in optoelectronic devices of hybrid organo-plumbate or stannate are a hot topic of academic research; more and more of such hybrids have been synthesized. Structurally, these hybrids are suitable for exploration of ferroelectricity. Therefore, the design of molecular ferroelectric semiconductors based on these hybrids provides a possibility to obtain new or high-performance semiconductor ferroelectrics. Here we investigated Pb-layered perovskites, and found the layer perovskite (benzylammonium)2PbCl4 is ferroelectric with semiconducting behaviours. It has a larger ferroelectric spontaneous polarization Ps=13 μC cm−2 and a higher Curie temperature Tc=438 K with a band gap of 3.65 eV. This finding throws light on the new properties of the hybrid organo-plumbate or stannate compounds and provides a new way to develop new semiconductor ferroelectrics. PMID:26021758

Improved Single-Source Precursors for Solar-Cell Absorbers

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Harris, Jerry; Hepp, Aloysius

2007-01-01

Improved single-source precursor compounds have been invented for use in spray chemical vapor deposition (spray CVD) of chalcopyrite semiconductor absorber layers of thin-film cells. A "single-source precursor compound" is a single molecular compound that contains all the required elements, which when used under the spray CVD conditions, thermally decomposes to form CuIn(x)Ga(1-x)S(y)Se(2-y).

Diode and method of making the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dickerson, Jeramy Ray; Wierer, Jr., Jonathan; Kaplar, Robert

2018-03-13

A diode includes a second semiconductor layer over a first semiconductor layer. The diode further includes a third semiconductor layer over the second semiconductor layer, where the third semiconductor layer includes a first semiconductor element over the second semiconductor layer. The third semiconductor layer additionally includes a second semiconductor element over the second semiconductor layer, wherein the second semiconductor element surrounds the first semiconductor element. Further, the third semiconductor layer includes a third semiconductor element over the second semiconductor element. Furthermore, a hole concentration of the second semiconductor element is less than a hole concentration of the first semiconductor element.

Rhenium ion beam for implantation into semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulevoy, T. V.; Seleznev, D. N.; Alyoshin, M. E.

2012-02-15

At the ion source test bench in Institute for Theoretical and Experimental Physics the program of ion source development for semiconductor industry is in progress. In framework of the program the Metal Vapor Vacuum Arc ion source for germanium and rhenium ion beam generation was developed and investigated. It was shown that at special conditions of ion beam implantation it is possible to fabricate not only homogenous layers of rhenium silicides solid solutions but also clusters of this compound with properties of quantum dots. At the present moment the compound is very interesting for semiconductor industry, especially for nanoelectronics andmore » nanophotonics, but there is no very developed technology for production of nanostructures (for example quantum sized structures) with required parameters. The results of materials synthesis and exploration are presented.« less

Infrared emitting device and method

DOEpatents

Kurtz, Steven R.; Biefeld, Robert M.; Dawson, L. Ralph; Howard, Arnold J.; Baucom, Kevin C.

1997-01-01

An infrared emitting device and method. The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region. Examples have been set forth showing embodiments of the present invention as surface- and edge-emitting light emitting diodes (LEDs), an optically-pumped semiconductor laser, and an electrically-injected semiconductor diode laser. The light emission from each of the infrared emitting devices of the present invention is in the midwave infrared region of the spectrum from about 2 to 6 microns.

Antimonide-Based Compound Semiconductors for Low-Power Electronics

DTIC Science & Technology

2013-01-01

A, Madan HS, Kirk AP, Zhao DA, Mourey DA, Hudait MK, et al. Fermi level unpinning of GaSb (100) using plasma enhanced atomic layer deposition of...et al. Atomic layer deposition of Al2O3 on GaSb using in situ hydrogen plasma exposure. Appl Phys Lett. 2012;101: 231601. [18] Ali A, Madan H

Methods for making thin layers of crystalline materials

DOEpatents

Lagally, Max G; Paskiewicz, Deborah M; Tanto, Boy

2013-07-23

Methods for making growth templates for the epitaxial growth of compound semiconductors and other materials are provided. The growth templates are thin layers of single-crystalline materials that are themselves grown epitaxially on a substrate that includes a thin layer of sacrificial material. The thin layer of sacrificial material, which creates a coherent strain in the single-crystalline material as it is grown thereon, includes one or more suspended sections and one or more supported sections.

Broadband light-emitting diode

DOEpatents

Fritz, Ian J.; Klem, John F.; Hafich, Michael J.

1998-01-01

A broadband light-emitting diode. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3-2 .mu.m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-division-multiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft.

Broadband light-emitting diode

DOEpatents

Fritz, I.J.; Klem, J.F.; Hafich, M.J.

1998-07-14

A broadband light-emitting diode is disclosed. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3--2 {micro}m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-divisionmultiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft. 10 figs.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Refractive indices of superlattices made of III-V semiconductor compounds and their solid solutions and semiconductor waveguide laser structures

NASA Astrophysics Data System (ADS)

Unger, K.

1988-11-01

An analysis is made of the theoretical problems encountered in precision calculations of refractive indices of semiconductor materials arising in connection with the use of superlattices as active layers in double-heterostructure lasers and in connection with the use of the impurity-induced disordering effect, i.e., the ability to transform selectively a superlattice into a corresponding solid solution. This can be done by diffusion or ion implantation. A review is given of calculations of refractive indices based on the knowledge of the energy band structure and the role of disorder is considered particularly. An anomaly observed in the (InAl)As system is considered. It is shown that the local field effects and exciton transitions are important. A reasonable approach is clearly a direct calculation of the difference between the refractive indices of superlattices based on compounds and of those based on their solid solutions.

Versatile buffer layer architectures based on Ge1-xSnx alloys

NASA Astrophysics Data System (ADS)

Roucka, R.; Tolle, J.; Cook, C.; Chizmeshya, A. V. G.; Kouvetakis, J.; D'Costa, V.; Menendez, J.; Chen, Zhihao D.; Zollner, S.

2005-05-01

We describe methodologies for integration of compound semiconductors with Si via buffer layers and templates based on the GeSn system. These layers exhibit atomically flat surface morphologies, low defect densities, tunable thermal expansion coefficients, and unique ductile properties, which enable them to readily absorb differential stresses produced by mismatched overlayers. They also provide a continuous selection of lattice parameters higher than that of Ge, which allows lattice matching with technologically useful III-V compounds. Using this approach we have demonstrated growth of GaAs, GeSiSn, and pure Ge layers at low temperatures on Si(100). These materials display extremely high-quality structural, morphological, and optical properties opening the possibility of versatile integration schemes directly on silicon.

Prediction of weak and strong topological insulators in layered semiconductors.

NASA Astrophysics Data System (ADS)

Felser, Claudia

2013-03-01

We investigate a new class of ternary materials such as LiAuSe and KHgSb with a honeycomb structure in Au-Se and Hg-Sb layers. We demonstrate the band inversion in these materials similar to HgTe, which is a strong precondition for existence of the topological surface states. In contrast with graphene, these materials exhibit strong spin-orbit coupling and a small direct band gap at the point. Since these materials are centrosymmetric, it is straightforward to determine the parity of their wave functions, and hence their topological character. Surprisingly, the compound with strong spin-orbit coupling (KHgSb) is trivial, whereas LiAuSe is found to be a topological insulator. However KHgSb is a weak topological insulators in case of an odd number of layers in the primitive unit cell. Here, the single-layered KHgSb shows a large bulk energy gap of 0.24 eV. Its side surface hosts metallic surface states, forming two anisotropic Dirac cones. Although the stacking of even-layered structures leads to trivial insulators, the structures can host a quantum spin Hall layer with a large bulk gap, if an additional single layer exists as a stacking fault in the crystal. The reported honeycomb compounds can serve as prototypes to aid in the finding of new weak topological insulators in layered small-gap semiconductors. In collaboration with Binghai Yan, Lukas Müchler, Hai-Jun Zhang, Shou-Cheng Zhang and Jürgen Kübler.

Spin-Polarized Tunneling at Interfaces Between Oxides and Metals or Semiconductors

DTIC Science & Technology

2006-09-01

solution 3 3. Several miscellaneous compounds , including molecular oxygen and organic biradicals 4. Metals When a variable magnetic field is...substrate layer) Heusler alloys are considered to be prime candidates, because they show great potential for spin-injection contacts to compound and...usually employ simple parabolic bands and/or momentum and energy independent tunneling matrix elements. The classical theory of tunneling assumes that the

Syntheses, structural variants and characterization of AInM′S{sub 4} (A=alkali metals, Tl; M′ = Ge, Sn) compounds; facile ion-exchange reactions of layered NaInSnS{sub 4} and KInSnS{sub 4} compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yohannan, Jinu P.; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

Ten AInM′S{sub 4} (A=alkali metals, Tl; M′= Ge, Sn) compounds with diverse structure types have been synthesized and characterized by single crystal and powder X-ray diffraction and a variety of spectroscopic methods. They are wide band gap semiconductors. KInGeS{sub 4}(1-β), RbInGeS{sub 4}(2), CsInGeS{sub 4}(3-β), TlInGeS{sub 4}(4-β), RbInSnS{sub 4}(8-β) and CsInSnS{sub 4}(9) compounds with three-dimensional BaGa{sub 2}S{sub 4} structure and CsInGeS{sub 4}(3-α) and TlInGeS{sub 4}(4-α) compounds with a layered TlInSiS{sub 4} structure have tetrahedral [InM′S{sub 4}]{sup −} frameworks. On the other hand, LiInSnS{sub 4}(5) with spinel structure and NaInSnS{sub 4}(6), KInSnS{sub 4}(7), RbInSnS{sub 4}(8-α) and TlInSnS{sub 4}(10) compounds with layered structuremore » have octahedral [InM′S{sub 4}]{sup −} frameworks. NaInSnS{sub 4}(6) and KInSnS{sub 4}(7) compounds undergo facile topotactic ion-exchange, at room temperature, with various mono-, di- and tri-valent cations in aqueous medium to give rise to metastable layered phases. - Graphical abstract: NaInSnS{sub 4} and KInSnS{sub 4} compounds undergo, in aqueous medium at room temperature, facile topotactic ion-exchange with mono, di and trivalent cations. Display Omitted - Highlights: • Ten AInM′S{sub 4} compounds with diverse structure types were synthesized. • They are wide band gap semiconductors. • NaInSnS{sub 4} and KInSnS{sub 4} compounds undergo facile topotactic ion-exchange at room temperature.« less

Semiconductor photoelectrochemistry

NASA Technical Reports Server (NTRS)

Buoncristiani, A. M.; Byvik, C. E.

1983-01-01

Semiconductor photoelectrochemical reactions are investigated. A model of the charge transport processes in the semiconductor, based on semiconductor device theory, is presented. It incorporates the nonlinear processes characterizing the diffusion and reaction of charge carriers in the semiconductor. The model is used to study conditions limiting useful energy conversion, specifically the saturation of current flow due to high light intensity. Numerical results describing charge distributions in the semiconductor and its effects on the electrolyte are obtained. Experimental results include: an estimate rate at which a semiconductor photoelectrode is capable of converting electromagnetic energy into chemical energy; the effect of cell temperature on the efficiency; a method for determining the point of zero zeta potential for macroscopic semiconductor samples; a technique using platinized titanium dioxide powders and ultraviolet radiation to produce chlorine, bromine, and iodine from solutions containing their respective ions; the photoelectrochemical properties of a class of layered compounds called transition metal thiophosphates; and a technique used to produce high conversion efficiency from laser radiation to chemical energy.

Ternary arsenides ATt{sub 3}As{sub 3} (A=K, Rb; Tt=Ge, Sn) with layered structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khatun, Mansura; Stoyko, Stanislav S.; Mar, Arthur, E-mail: arthur.mar@ualberta.ca

2016-06-15

The four ternary arsenides ATt{sub 3}As{sub 3} (A=K, Rb; Tt=Ge, Sn) were obtained by reaction of the elements at 600–650 °C. They adopt an orthorhombic structure (space group Pnma, Z=4, with cell parameters ranging from a=9.9931(11) Å, b=3.7664(4) Å, c=18.607(2) Å for KGe{sub 3}As{sub 3} to a=10.3211(11) Å, b=4.0917(4) Å, c=19.570(2) Å for RbSn{sub 3}As{sub 3}) containing corrugated [Tt{sub 3}As{sub 3}] layers built from Tt-centred trigonal pyramids and tetrahedra forming five-membered rings decorated with As handles. They can be considered to be Zintl phases with Tt atoms in +4, +3, and +1 oxidation states. Band structure calculations predict that thesemore » compounds are semiconductors with narrow band gaps (0.71 eV in KGe{sub 3}As{sub 3}, 0.50 eV in KSn{sub 3}As{sub 3}). - Graphical abstract: Ternary arsenides ATt{sub 3}As{sub 3} (A=K, Rb; Tt=Ge, Sn) contain corrugated layers with Tt atoms in three different oxidation states and are narrow band gap semiconductors. Display Omitted - Highlights: • ATt{sub 3}As{sub 3} (A=K, Rb; Tt=Ge, Sn) contains Tt atoms in three oxidation states. • The structure differs from NaGe{sub 3}P{sub 3} in terms of layer stacking arrangement. • The compounds are predicted to be narrow band gap semiconductors.« less

Semiconductor structure and recess formation etch technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Bin; Sun, Min; Palacios, Tomas Apostol

2017-02-14

A semiconductor structure has a first layer that includes a first semiconductor material and a second layer that includes a second semiconductor material. The first semiconductor material is selectively etchable over the second semiconductor material using a first etching process. The first layer is disposed over the second layer. A recess is disposed at least in the first layer. Also described is a method of forming a semiconductor structure that includes a recess. The method includes etching a region in a first layer using a first etching process. The first layer includes a first semiconductor material. The first etching processmore » stops at a second layer beneath the first layer. The second layer includes a second semiconductor material.« less

Method of making photovoltaic cell

DOEpatents

Cruz-Campa, Jose Luis; Zhou, Xiaowang; Zubia, David

2017-06-20

A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

Optically switched graphene/4H-SiC junction bipolar transistor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandrashekhar, MVS; Sudarshan, Tangali S.; Omar, Sabih U.

A bi-polar device is provided, along with methods of making the same. The bi-polar device can include a semiconductor substrate doped with a first dopant, a semiconductor layer on the first surface of the semiconductor substrate, and a Schottky barrier layer on the semiconductor layer. The method of forming a bi-polar device can include: forming a semiconductor layer on a first surface of a semiconductor substrate, where the semiconductor substrate comprises a first dopant and where the semiconductor layer comprises a second dopant that has an opposite polarity than the first dopant; and forming a Schottky barrier layer on amore » first portion of the semiconductor layer while leaving a second portion of the semiconductor layer exposed.« less

High quality lamella preparation of gallium nitride compound semiconductor using Triple Beam™ system

NASA Astrophysics Data System (ADS)

Sato, T.; Nakano, K.; Matsumoto, H.; Torikawa, S.; Nakatani, I.; Kiyohara, M.; Isshiki, T.

2017-09-01

Gallium nitride (GaN) compound semiconductors have been known to be very sensitive to Ga focused ion beam (FIB) processing. Due to the nature of GaN based materials it is often difficult to produce damage-free lamellae, therefore applying the Triple Beam™ system which incorporates an enhanced method for amorphous removal is presented to make a high quality lamella. The damage or distortion layer thickness of GaN single crystal prepared with 30 kV Ga FIB and 1 kV Ga FIB were about 17 nm and 1.5 nm respectively. The crystallinity at the uppermost surface remained unaffected when the condition of 1 kV Ar ion milling with the Triple Beam™ system was used. The technique of combining traditional Ga FIB processing with an enhanced method for amorphous layer removal by low energy Ar ion milling allows us to analyse the InGaN/GaN interface using aberration corrected scanning transmission electron microscopy at atomic resolution levels.

X-ray diffraction study of the molecular propolis films deposited from an alcohol solution onto the cleavage surfaces of layered V2VI3 compounds

NASA Astrophysics Data System (ADS)

Drapak, S. I.; Gavrylyuk, S. V.; Kaminskii, V. M.; Kovalyuk, Z. D.

2008-09-01

The structures of the molecular propolis films deposited from an alcohol solution on the (0001) cleavage surface of layered bismuth selenide and telluride are studied by X-ray diffraction. Despite the chemical interaction between the semiconductor substrates and the organic-substance components, the molecular structural ordering of the propolis films is shown to be identical to that in the films of this substance on the surface of amorphous glass substrates. The chemical and deformation interaction between the organic substance and the layered V2VI3 compounds is found to result in the formation of an organic-inorganic sandwich nanostructure at a distance of ˜0.3 μm from the layered crystal-propolis film interface.

Photovoltaic cell with nano-patterned substrate

DOEpatents

Cruz-Campa, Jose Luis; Zhou, Xiaowang; Zubia, David

2016-10-18

A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors

NASA Astrophysics Data System (ADS)

Biyikli, Necmi; Haider, Ali

2017-09-01

In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.

Method of making silicon on insalator material using oxygen implantation

DOEpatents

Hite, Larry R.; Houston, Ted; Matloubian, Mishel

1989-01-01

The described embodiments of the present invention provide a semiconductor on insulator structure providing a semiconductor layer less susceptible to single event upset errors (SEU) due to radiation. The semiconductor layer is formed by implanting ions which form an insulating layer beneath the surface of a crystalline semiconductor substrate. The remaining crystalline semiconductor layer above the insulating layer provides nucleation sites for forming a crystalline semiconductor layer above the insulating layer. The damage caused by implantation of the ions for forming an insulating layer is left unannealed before formation of the semiconductor layer by epitaxial growth. The epitaxial layer, thus formed, provides superior characteristics for prevention of SEU errors, in that the carrier lifetime within the epitaxial layer, thus formed, is less than the carrier lifetime in epitaxial layers formed on annealed material while providing adequate semiconductor characteristics.

PEALD grown high-k ZrO{sub 2} thin films on SiC group IV compound semiconductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khairnar, A. G., E-mail: agkhairnar@gmail.com; Patil, V. S.; Agrawal, K. S.

The study of ZrO{sub 2} thin films on SiC group IV compound semiconductor has been studied as a high mobility substrates. The ZrO{sub 2} thin films were deposited using the Plasma Enhanced Atomic Layer Deposition System. The thickness of the thin films were measured using ellipsometer and found to be 5.47 nm. The deposited ZrO{sub 2} thin films were post deposition annealed in rapid thermal annealing chamber at temperature of 400°Ð¡. The atomic force microscopy and X-гау photoelectron spectroscopy has been carried out to study the surface topography, roughness and chemical composition of thin film, respectively.

Direct observation of dopant distribution in GaAs compound semiconductors using phase-shifting electron holography and Lorentz microscopy.

PubMed

Sasaki, Hirokazu; Otomo, Shinya; Minato, Ryuichiro; Yamamoto, Kazuo; Hirayama, Tsukasa

2014-06-01

Phase-shifting electron holography and Lorentz microscopy were used to map dopant distributions in GaAs compound semiconductors with step-like dopant concentration. Transmission electron microscope specimens were prepared using a triple beam focused ion beam (FIB) system, which combines a Ga ion beam, a scanning electron microscope, and an Ar ion beam to remove the FIB damaged layers. The p-n junctions were clearly observed in both under-focused and over-focused Lorentz microscopy images. A phase image was obtained by using a phase-shifting reconstruction method to simultaneously achieve high sensitivity and high spatial resolution. Differences in dopant concentrations between 1 × 10(19) cm(-3) and 1 × 10(18) cm(-3) regions were clearly observed by using phase-shifting electron holography. We also interpreted phase profiles quantitatively by considering inactive layers induced by ion implantation during the FIB process. The thickness of an inactive layer at different dopant concentration area can be measured from the phase image. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Alkali layered compounds interfaces for energy conversion and energy storage

NASA Technical Reports Server (NTRS)

Papageorgopoulos, Chris A.

1996-01-01

During year one a new ultra-high vacuum, an Ar(+) ion sputterer, a low energy electron diffraction (LEED) system, an Auger electron spectrometer (AES), a work function measurement device with a Kelvin probe, and related accessories were used. The study found a focus in the adsorption of chalcogenides on Si and III-V compound semiconductors. In the second year, a scanning tunneling microscope was obtained along with a quadrapole mass spectrometer, power supplies, a computer, a chart recorder, etc. We started the systematic study on the adsorption of chalcogenides on the compound semiconductor surfaces. The third year saw the mounting of the scanning tunneling microscope (STM) on the existing UHV system. The investigation continued with the adsorption of Cs (alkali) on S-covered Si(100)2x1 surfaces. Then the adsorption of S on Cs-covered Si(100) surfaces was studied.

Vapor phase growth technique of III-V compounds utilizing a preheating step

NASA Technical Reports Server (NTRS)

Olsen, Gregory Hammond (Inventor); Zamerowski, Thomas Joseph (Inventor); Buiocchi, Charles Joseph (Inventor)

1978-01-01

In the vapor phase epitaxy fabrication of semiconductor devices and in particular semiconductor lasers, the deposition body on which a particular layer of the laser is to be grown is preheated to a temperature about 40.degree. to 60.degree. C. lower than the temperature at which deposition occurs. It has been discovered that by preheating at this lower temperature there is reduced thermal decomposition at the deposition surface, especially for semiconductor materials such as indium gallium phosphide and gallium arsenide phosphide. A reduction in thermal decomposition reduces imperfections in the deposition body in the vicinity of the deposition surface, thereby providing a device with higher efficiency and longer lifetime.

Material growth and characterization for solid state devices

NASA Technical Reports Server (NTRS)

Collis, Ward J.; Abul-Fadl, Ali; Iyer, Shanthi

1988-01-01

During the period of this research grant, the process of liquid phase electroepitaxy (LPEE) was used to grow ternary and quaternary alloy III-V semiconductor thin films. Selective area growth of InGaAs was performed on InP substrates using a patterned sputtered quartz or spin-on glass layer. The etch back and growth characteristics with respect to substrate orientation were investigated. The etch back behavior is somewhat different from wet chemical etching with respect to the sidewall profiles which are observed. LPEE was also employed to grow epitaxial layers of InGaAsP alloys on InP substrates. The behavior of Mn as an acceptor dopant was investigated with low temperature Hall coefficient and photoluminescence measurements. A metal-organic vapor phase epitaxy system was partially complete within the grant period. This atmospheric pressure system will be used to deposit III-V compound and alloy semiconductor layers in future research efforts.

Synthesis, characterization and air stable semiconductor properties of thiophene-condensed pyrene derivatives

NASA Astrophysics Data System (ADS)

Moriguchi, Tetsuji; Higashi, Makoto; Yakeya, Daisuke; Jalli, Venkataprasad; Tsuge, Akihiko; Okauchi, Tatsuo; Nagamatsu, Shuichi; Takashima, Wataru

2017-01-01

New and simple polyaromatic compounds containing two thiophene rings were prepared via photo-cyclization and their structural and photophysical properties were evaluated via 1H NMR spectroscopy and X-ray crystallographic analysis. On the basis of X-ray analysis, it was determined that the molecular structure of the compound was highly strained and that they contain two hetero [4] helicene moieties. The compounds were investigated as active layer in p-type organic field-effect transistors (p-OFET) in top contact type devices. Notably, the compound containing two thiophene components exhibited very stable p-type semiconducting behavior in moist air.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahal, Rajendra P.; Bhat, Ishwara B.; Chow, Tat-Sing

Methods for facilitating fabricating semiconductor structures are provided which include: providing a multilayer structure including a semiconductor layer, the semiconductor layer including a dopant and having an increased conductivity; selectively increasing, using electrochemical processing, porosity of the semiconductor layer, at least in part, the selectively increasing porosity utilizing the increased conductivity of the semiconductor layer; and removing, at least in part, the semiconductor layer with the selectively increased porosity from the multilayer structure. By way of example, the selectively increasing porosity may include selectively, anodically oxidizing, at least in part, the semiconductor layer of the multilayer structure.

Single-layer group IV-V and group V-IV-III-VI semiconductors: Structural stability, electronic structures, optical properties, and photocatalysis

NASA Astrophysics Data System (ADS)

Lin, Jia-He; Zhang, Hong; Cheng, Xin-Lu; Miyamoto, Yoshiyuki

2017-07-01

Recently, single-layer group III monochalcogenides have attracted both theoretical and experimental interest at their potential applications in photonic devices, electronic devices, and solar energy conversion. Excited by this, we theoretically design two kinds of highly stable single-layer group IV-V (IV =Si ,Ge , and Sn; V =N and P) and group V-IV-III-VI (IV =Si ,Ge , and Sn; V =N and P; III =Al ,Ga , and In; VI =O and S) compounds with the same structures with single-layer group III monochalcogenides via first-principles simulations. By using accurate hybrid functional and quasiparticle methods, we show the single-layer group IV-V and group V-IV-III-VI are indirect bandgap semiconductors with their bandgaps and band edge positions conforming to the criteria of photocatalysts for water splitting. By applying a biaxial strain on single-layer group IV-V, single-layer group IV nitrides show a potential on mechanical sensors due to their bandgaps showing an almost linear response for strain. Furthermore, our calculations show that both single-layer group IV-V and group V-IV-III-VI have absorption from the visible light region to far-ultraviolet region, especially for single-layer SiN-AlO and SnN-InO, which have strong absorption in the visible light region, resulting in excellent potential for solar energy conversion and visible light photocatalytic water splitting. Our research provides valuable insight for finding more potential functional two-dimensional semiconductors applied in optoelectronics, solar energy conversion, and photocatalytic water splitting.

Bulk semiconducting scintillator device for radiation detection

DOEpatents

Stowe, Ashley C.; Burger, Arnold; Groza, Michael

2016-08-30

A bulk semiconducting scintillator device, including: a Li-containing semiconductor compound of general composition Li-III-VI.sub.2, wherein III is a Group III element and VI is a Group VI element; wherein the Li-containing semiconductor compound is used in one or more of a first mode and a second mode, wherein: in the first mode, the Li-containing semiconductor compound is coupled to an electrical circuit under bias operable for measuring electron-hole pairs in the Li-containing semiconductor compound in the presence of neutrons and the Li-containing semiconductor compound is also coupled to current detection electronics operable for detecting a corresponding current in the Li-containing semiconductor compound; and, in the second mode, the Li-containing semiconductor compound is coupled to a photodetector operable for detecting photons generated in the Li-containing semiconductor compound in the presence of the neutrons.

III-V compound semiconductor growth on silicon via germanium buffer and surface passivation for CMOS technology

NASA Astrophysics Data System (ADS)

Choi, Donghun

Integration of III-V compound semiconductors on silicon substrates has recently received much attention for the development of optoelectronic and high speed electronic devices. However, it is well known that there are some key challenges for the realization of III-V device fabrication on Si substrates: (i) the large lattice mismatch (in case of GaAs: 4.1%), and (ii) the formation of antiphase domain (APD) due to the polar compound semiconductor growth on non-polar elemental structure. Besides these growth issues, the lack of a useful surface passivation technology for compound semiconductors has precluded development of metal-oxide-semiconductor (MOS) devices and causes high surface recombination parasitics in scaled devices. This work demonstrates the growth of high quality III-V materials on Si via an intermediate Ge buffer layer and some surface passivation methods to reduce interface defect density for the fabrication of MOS devices. The initial goal was to achieve both low threading dislocation density (TDD) and low surface roughness on Ge-on-Si heterostructure growth. This was achieved by repeating a deposition-annealing cycle consisting of low temperature deposition + high temperature-high rate deposition + high temperature hydrogen annealing, using reduced-pressure chemical-vapor deposition (CVD). We then grew III-V materials on the Ge/Si virtual substrates using molecular-beam epitaxy (MBE). The relationship between initial Ge surface configuration and antiphase boundary formation was investigated using surface reflection high-energy electron diffraction (RHEED) patterns and atomic force microscopy (AFM) image analysis. In addition, some MBE growth techniques, such as migration enhanced epitaxy (MEE) and low temperature GaAs growth, were adopted to improve surface roughness and solve the Ge self-doping problem. Finally, an Al2O3 gate oxide layer was deposited using atomic-layer-deposition (ALD) system after HCl native oxide etching and ALD in-situ pre-annealing at 400 °C. A 100 nm thick aluminum layer was deposited to form the gate contact for a MOS device fabrication. C-V measurement results show very small frequency dispersion and 200-300 mV hysteresis, comparable to our best results for InGaAs/GaAs MOS structures on GaAs substrate. Most notably, the quasi-static C-V curve demonstrates clear inversion layer formation. I-V curves show a reasonable leakage current level. The inferred midgap interface state density, Dit, of 2.4 x 1012 eV-1cm-2 was calculated by combined high-low frequency capacitance method. In addition, we investigated the interface properties of amorphous LaAlO 3/GaAs MOS capacitors fabricated on GaAs substrate. The surface was protected during sample transfer between III-V and oxide molecular beam deposition (MBD) chambers by a thick arsenic-capping layer. An annealing method, a low temperature-short time RTA followed by a high temperature RTA, was developed, yielding extremely small hysteresis (˜ 30 mV), frequency dispersion (˜ 60 mV), and interface trap density (mid 1010 eV-1cm -2). We used capacitance-voltage (C-V) and current-voltage (I-V) measurements for electrical characterization of MOS devices, tapping-mode AFM for surface morphology analysis, X-ray photoelectron spectroscopy (XPS) for chemical elements analysis of interface, cross section transmission-electron microscopy (TEM), X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), and photoluminescence (PL) measurement for film quality characterization. This successful growth and appropriate surface treatments of III-V materials provides a first step for the fabrication of III-V optical and electrical devices on the same Si-based electronic circuits.

Long wavelength, high gain InAsSb strained-layer superlattice photoconductive detectors

DOEpatents

Biefeld, Robert M.; Dawson, L. Ralph; Fritz, Ian J.; Kurtz, Steven R.; Zipperian, Thomas E.

1991-01-01

A high gain photoconductive device for 8 to 12 .mu.m wavelength radiation including an active semiconductor region extending from a substrate to an exposed face, the region comprising a strained-layer superlattice of alternating layers of two different InAs.sub.1-x Sb.sub.x compounds having x>0.75. A pair of spaced electrodes are provided on the exposed face, and changes in 8 to 12 .mu.m radiation on the exposed face cause a large photoconductive gain between the spaced electrodes.

Fused thiophene and its periphery fluorinated substitution derivatives: a theoretical study for organic semiconductors

NASA Astrophysics Data System (ADS)

Wei, Hui-Ling; Shi, Ya-Rui; Liu, Yu-Fang

2015-06-01

A series of phenyl end-capped derivatives of benzo[d,d‧]thieno[3,2-b4,5- b‧]dithiophene (BTDT) with periphery-fluorinated substitutions (PFS) were systematically investigated by using density functional theory (DFT) combined with the Marcus-Hush electron transfer theory. The substituting effects of PFS were discussed. Compared with the original compounds, (i) the PFS compounds have a relatively higher efficiency of charge transport, lower barriers of electron injection, and larger HOMO-LUMO gaps; (ii) the air-stability and the device performance are enhanced by PFS; and (iii) the HOMO-LUMO transitions in the absorption spectrum of the PFS compounds show an obvious blue-shift trend. The perfluorophenylbisbenzo[d, d‧]thieno[3,2-b4,5-b‧]dithiophene (BpF-BTDT) is found to be the most stable and most effective compound in charge transport among the investigated compounds, and it is suggested as an ambipolar semiconducting material. The results of electronic coupling of the bisbenzo[d, d‧]thieno[3,2-b 4,5- b‧]dithiophene (BBTDT) derivatives show that the orbital interaction is mainly contributed by the neighboring molecule in the two dimensional (2D) layer. The PFS compounds have lower oxidization potential, ionization potential, and electron affinity values than the corresponding original ones, which suggest that fluorination can enhance the performance of the thiophene-based organic solar cells. These findings provide a better understanding of the PFS effects on organic semiconductors and may help to design high-performance semiconductor materials.

Optical NAND gate

DOEpatents

Skogen, Erik J [Albuquerque, NM; Raring, James [Goleta, CA; Tauke-Pedretti, Anna [Albuquerque, NM

2011-08-09

An optical NAND gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator and a photodetector. One pair of the optical waveguide devices is electrically connected in parallel to operate as an optical AND gate; and the other pair of the optical waveguide devices is connected in series to operate as an optical NOT gate (i.e. an optical inverter). The optical NAND gate utilizes two digital optical inputs and a continuous light input to provide a NAND function output. The optical NAND gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Electrochemical Atomic Layer Epitaxy of Thin Film CdSe

NASA Astrophysics Data System (ADS)

Pham, L.; Kaleida, K.; Happek, U.; Mathe, M. K.; Vaidyanathan, R.; Stickney, J. L.; Radevic, M.

2002-10-01

Electrochemical atomic layer epitaxy (EC-ALE) is a current developmental technique for the fabrication of compound semiconductor thin films. The deposition of elements making up the compound utilizes surface limited reactions where the potential is less than that required for bulk growth. This growth method offers mono-atomic layer control, allowing the deposition of superlattices with sharp interfaces. Here we report on the EC-ALE formation of CdSe thin films on Au and Cu substrates using an automated flow cell system. The band gap was measured using IR absorption and photoconductivity and found to be consistent with the literature value of 1.74 eV at 300K and 1.85 eV at 20K. The stoichiometry of the thin film was confirmed with electron microprobe analysis and x-ray diffraction.

Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

NASA Astrophysics Data System (ADS)

Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong; Ma, Zhongquan

2016-12-01

A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

Architectures and criteria for the design of high efficiency organic photovoltaic cells

DOEpatents

Rand, Barry; Forrest, Stephen R; Burk, Diana Pendergrast

2015-03-24

An organic photovoltaic cell includes an anode and a cathode, and a plurality of organic semiconductor layers between the anode and the cathode. At least one of the anode and the cathode is transparent. Each two adjacent layers of the plurality of organic semiconductor layers are in direct contact. The plurality of organic semiconductor layers includes an intermediate layer consisting essentially of a photoconductive material, and two sets of at least three layers. A first set of at least three layers is between the intermediate layer and the anode. Each layer of the first set consists essentially of a different organic semiconductor material having a higher LUMO and a higher HOMO, relative to the material of an adjacent layer of the plurality of organic semiconductor layers closer to the cathode. A second set of at least three layers is between the intermediate layer and the cathode. Each layer of the second set consists essentially of a different organic semiconductor material having a lower LUMO and a lower HOMO, relative to the material of an adjacent layer of the plurality of organic semiconductor layers closer to the anode.

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors

PubMed Central

Walters, Diane M.; Lyubimov, Ivan; de Pablo, Juan J.; Ediger, M. D.

2015-01-01

Physical vapor deposition is commonly used to prepare organic glasses that serve as the active layers in light-emitting diodes, photovoltaics, and other devices. Recent work has shown that orienting the molecules in such organic semiconductors can significantly enhance device performance. We apply a high-throughput characterization scheme to investigate the effect of the substrate temperature (Tsubstrate) on glasses of three organic molecules used as semiconductors. The optical and material properties are evaluated with spectroscopic ellipsometry. We find that molecular orientation in these glasses is continuously tunable and controlled by Tsubstrate/Tg, where Tg is the glass transition temperature. All three molecules can produce highly anisotropic glasses; the dependence of molecular orientation upon substrate temperature is remarkably similar and nearly independent of molecular length. All three compounds form “stable glasses” with high density and thermal stability, and have properties similar to stable glasses prepared from model glass formers. Simulations reproduce the experimental trends and explain molecular orientation in the deposited glasses in terms of the surface properties of the equilibrium liquid. By showing that organic semiconductors form stable glasses, these results provide an avenue for systematic performance optimization of active layers in organic electronics. PMID:25831545

Method of producing strained-layer semiconductor devices via subsurface-patterning

DOEpatents

Dodson, Brian W.

1993-01-01

A method is described for patterning subsurface features in a semiconductor device, wherein the semiconductor device includes an internal strained layer. The method comprises creating a pattern of semiconductor material over the semiconductor device, the semiconductor material having a predetermined thickness which stabilizes areas of the strained semiconductor layer that lie beneath the pattern. Subsequently, a heating step is applied to the semiconductor device to cause a relaxation in areas of the strained layer which do not lie beneath the semiconductor material pattern, whereby dislocations result in the relaxed areas and impair electrical transport therethrough.

Donor impurity incorporation during layer growth of Zn II-VI semiconductors

NASA Astrophysics Data System (ADS)

Barlow, D. A.

2017-12-01

The maximum halogen donor concentration in Zn II-VI semiconductors during layer growth is studied using a standard model from statistical mechanics. Here the driving force for incorporation is an increase in entropy upon mixing of the donor impurity into the available anion lattice sites in the host binary. A formation energy opposes this increase and thus equilibrium is attained at some maximum concentration. Considering the halogen donor impurities within the Zn II-VI binary semiconductors ZnO, ZnS, ZnSe and ZnTe, a heat of reaction obtained from reported diatomic bond strengths is shown to be directly proportional to the log of maximum donor concentration. The formation energy can then be estimated and an expression for maximum donor concentration derived. Values for the maximum donor concentration with each of the halogen impurities, within the Zn II-VI compounds, are computed. This model predicts that the halogens will serve as electron donors in these compounds in order of increasing effectiveness as: F, Br, I, Cl. Finally, this result is taken to be equivalent to an alternative model where donor concentration depends upon impurity diffusion and the conduction band energy shift due to a depletion region at the growing crystal's surface. From this, we are able to estimate the diffusion activation energy for each of the impurities mentioned above. Comparisons are made with reported values and relevant conclusions presented.

Method of transferring a thin crystalline semiconductor layer

DOEpatents

Nastasi, Michael A [Sante Fe, NM; Shao, Lin [Los Alamos, NM; Theodore, N David [Mesa, AZ

2006-12-26

A method for transferring a thin semiconductor layer from one substrate to another substrate involves depositing a thin epitaxial monocrystalline semiconductor layer on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the thin semiconductor layer is bonded to a second substrate and the thin layer is separated away at the interface, which results in transferring the thin epitaxial semiconductor layer from one substrate to the other substrate.

Variable temperature semiconductor film deposition

DOEpatents

Li, X.; Sheldon, P.

1998-01-27

A method of depositing a semiconductor material on a substrate is disclosed. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

Variable temperature semiconductor film deposition

DOEpatents

Li, Xiaonan; Sheldon, Peter

1998-01-01

A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

Rapid Thermal Processing of 3-5 Compound Semiconductors with Application to the Fabrication of Microwave Devices

DTIC Science & Technology

1988-05-01

LE i GOD~’Q~/ SOLID STATE ELECTRONICS LABORATORY STANFORD ELECTRON ICS LABORATORIES DEPARTMENT OF ELECTRICAL ENGINEERING L STANFORD UNIVERSITY...defects in the growth of subsequent layers. Test structures consisting 325 zEP-H~ PrzC~ LE of multiple layers of GaAs or alternating lay ers of GaAs...QA5) ~erhfellowship. ’J L Ho~ viand ) IF Gibtxn,. itecr Res Soc S% mp Proc 52. 15119t 36 Rapid thermal annealing of Si-implanted GaAs with

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.

Design and exploration of semiconductors from first principles: A review of recent advances

NASA Astrophysics Data System (ADS)

Oba, Fumiyasu; Kumagai, Yu

2018-06-01

Recent first-principles approaches to semiconductors are reviewed, with an emphasis on theoretical insight into emerging materials and in silico exploration of as-yet-unreported materials. As relevant theory and methodologies have developed, along with computer performance, it is now feasible to predict a variety of material properties ab initio at the practical level of accuracy required for detailed understanding and elaborate design of semiconductors; these material properties include (i) fundamental bulk properties such as band gaps, effective masses, dielectric constants, and optical absorption coefficients; (ii) the properties of point defects, including native defects, residual impurities, and dopants, such as donor, acceptor, and deep-trap levels, and formation energies, which determine the carrier type and density; and (iii) absolute and relative band positions, including ionization potentials and electron affinities at semiconductor surfaces, band offsets at heterointerfaces between dissimilar semiconductors, and Schottky barrier heights at metal–semiconductor interfaces, which are often discussed systematically using band alignment or lineup diagrams. These predictions from first principles have made it possible to elucidate the characteristics of semiconductors used in industry, including group III–V compounds such as GaN, GaP, and GaAs and their alloys with related Al and In compounds; amorphous oxides, represented by In–Ga–Zn–O transparent conductive oxides (TCOs), represented by In2O3, SnO2, and ZnO; and photovoltaic absorber and buffer layer materials such as CdTe and CdS among group II–VI compounds and chalcopyrite CuInSe2, CuGaSe2, and CuIn1‑ x Ga x Se2 (CIGS) alloys, in addition to the prototypical elemental semiconductors Si and Ge. Semiconductors attracting renewed or emerging interest have also been investigated, for instance, divalent tin compounds, including SnO and SnS; wurtzite-derived ternary compounds such as ZnSnN2 and CuGaO2; perovskite oxides such as SrTiO3 and BaSnO3; and organic–inorganic hybrid perovskites, represented by CH3NH3PbI3. Moreover, the deployment of first-principles calculations allows us to predict the crystal structure, stability, and properties of as-yet-unreported materials. Promising materials have been explored via high-throughput screening within either publicly available computational databases or unexplored composition and structure space. Reported examples include the identification of nitride semiconductors, TCOs, solar cell photoabsorber materials, and photocatalysts, some of which have been experimentally verified. Machine learning in combination with first-principles calculations has emerged recently as a technique to accelerate and enhance in silico screening. A blend of computation and experimentation with data science toward the development of materials is often referred to as materials informatics and is currently attracting growing interest.

Optical data latch

DOEpatents

Vawter, G Allen [Corrales, NM

2010-08-31

An optical data latch is formed on a substrate from a pair of optical logic gates in a cross-coupled arrangement in which optical waveguides are used to couple an output of each gate to an photodetector input of the other gate. This provides an optical bi-stability which can be used to store a bit of optical information in the latch. Each optical logic gate, which can be an optical NOT gate (i.e. an optical inverter) or an optical NOR gate, includes a waveguide photodetector electrically connected in series with a waveguide electroabsorption modulator. The optical data latch can be formed on a III-V compound semiconductor substrate (e.g. an InP or GaAs substrate) from III-V compound semiconductor layers. A number of optical data latches can be cascaded to form a clocked optical data shift register.

Determination of atomic vacancies in InAs/GaSb strained-layer superlattices by atomic strain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Honggyu; Meng, Yifei; Kwon, Ji-Hwan

Determining vacancy in complex crystals or nanostructures represents an outstanding crystallographic problem that has a large impact on technology, especially for semiconductors, where vacancies introduce defect levels and modify the electronic structure. However, vacancy is hard to locate and its structure is difficult to probe experimentally. Reported here are atomic vacancies in the InAs/GaSb strained-layer superlattice (SLS) determined by atomic-resolution strain mapping at picometre precision. It is shown that cation and anion vacancies in the InAs/GaSb SLS give rise to local lattice relaxations, especially the nearest atoms, which can be detected using a statistical method and confirmed by simulation. Themore » ability to map vacancy defect-induced strain and identify its location represents significant progress in the study of vacancy defects in compound semiconductors.« less

Determination of atomic vacancies in InAs/GaSb strained-layer superlattices by atomic strain

DOE PAGES

Kim, Honggyu; Meng, Yifei; Kwon, Ji-Hwan; ...

2018-01-01

Determining vacancy in complex crystals or nanostructures represents an outstanding crystallographic problem that has a large impact on technology, especially for semiconductors, where vacancies introduce defect levels and modify the electronic structure. However, vacancy is hard to locate and its structure is difficult to probe experimentally. Reported here are atomic vacancies in the InAs/GaSb strained-layer superlattice (SLS) determined by atomic-resolution strain mapping at picometre precision. It is shown that cation and anion vacancies in the InAs/GaSb SLS give rise to local lattice relaxations, especially the nearest atoms, which can be detected using a statistical method and confirmed by simulation. Themore » ability to map vacancy defect-induced strain and identify its location represents significant progress in the study of vacancy defects in compound semiconductors.« less

Overview of atomic layer etching in the semiconductor industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanarik, Keren J., E-mail: keren.kanarik@lamresearch.com; Lill, Thorsten; Hudson, Eric A.

2015-03-15

Atomic layer etching (ALE) is a technique for removing thin layers of material using sequential reaction steps that are self-limiting. ALE has been studied in the laboratory for more than 25 years. Today, it is being driven by the semiconductor industry as an alternative to continuous etching and is viewed as an essential counterpart to atomic layer deposition. As we enter the era of atomic-scale dimensions, there is need to unify the ALE field through increased effectiveness of collaboration between academia and industry, and to help enable the transition from lab to fab. With this in mind, this article providesmore » defining criteria for ALE, along with clarification of some of the terminology and assumptions of this field. To increase understanding of the process, the mechanistic understanding is described for the silicon ALE case study, including the advantages of plasma-assisted processing. A historical overview spanning more than 25 years is provided for silicon, as well as ALE studies on oxides, III–V compounds, and other materials. Together, these processes encompass a variety of implementations, all following the same ALE principles. While the focus is on directional etching, isotropic ALE is also included. As part of this review, the authors also address the role of power pulsing as a predecessor to ALE and examine the outlook of ALE in the manufacturing of advanced semiconductor devices.« less

Semiconductor nanocrystal-based phagokinetic tracking

DOEpatents

Alivisatos, A Paul; Larabell, Carolyn A; Parak, Wolfgang J; Le Gros, Mark; Boudreau, Rosanne

2014-11-18

Methods for determining metabolic properties of living cells through the uptake of semiconductor nanocrystals by cells. Generally the methods require a layer of neutral or hydrophilic semiconductor nanocrystals and a layer of cells seeded onto a culture surface and changes in the layer of semiconductor nanocrystals are detected. The observed changes made to the layer of semiconductor nanocrystals can be correlated to such metabolic properties as metastatic potential, cell motility or migration.

Group I-III-VI.sub.2 semiconductor films for solar cell application

DOEpatents

Basol, Bulent M.; Kapur, Vijay K.

1991-01-01

This invention relates to an improved thin film solar cell with excellent electrical and mechanical integrity. The device comprises a substrate, a Group I-III-VI.sub.2 semiconductor absorber layer and a transparent window layer. The mechanical bond between the substrate and the Group I-III-VI.sub.2 semiconductor layer is enhanced by an intermediate layer between the substrate and the Group I-III-VI.sub.2 semiconductor film being grown. The intermediate layer contains tellurium or substitutes therefor, such as Se, Sn, or Pb. The intermediate layer improves the morphology and electrical characteristics of the Group I-III-VI.sub.2 semiconductor layer.

Buried Porous Silicon-Germanium Layers in Monocrystalline Silicon Lattices

NASA Technical Reports Server (NTRS)

Fathauer, Robert W. (Inventor); George, Thomas (Inventor); Jones, Eric W. (Inventor)

1998-01-01

Monocrystalline semiconductor lattices with a buried porous semiconductor layer having different chemical composition is discussed and monocrystalline semiconductor superlattices with a buried porous semiconductor layers having different chemical composition than that of its monocrystalline semiconductor superlattice are discussed. Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si-Ge layers followed by patterning into mesa structures. The mesa structures are strain etched resulting in porosification of the Si-Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si-Ge layers produced in a similar manner emitted visible light at room temperature.

Semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Marcel; Alivisatos, Paul

2014-01-28

A semiconductor nanocrystal compound and probe are described. The compound is capable of linking to one or more affinity molecules. The compound comprises (1) one or more semiconductor nanocrystals capable of, in response to exposure to a first energy, providing a second energy, and (2) one or more linking agents, having a first portion linked to the one or more semiconductor nanocrystals and a second portion capable of linking to one or more affinity molecules. One or more semiconductor nanocrystal compounds are linked to one or more affinity molecules to form a semiconductor nanocrystal probe capable of bonding with one or more detectable substances in a material being analyzed, and capable of, in response to exposure to a first energy, providing a second energy. Also described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and treating materials with the probe.

Semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, Shimon; Bruchez, Marcel; Alivisatos, Paul A.

2016-12-27

A semiconductor nanocrystal compound and probe are described. The compound is capable of linking to one or more affinity molecules. The compound comprises (1) one or more semiconductor nanocrystals capable of, in response to exposure to a first energy, providing a second energy, and (2) one or more linking agents, having a first portion linked to the one or more semiconductor nanocrystals and a second portion capable of linking to one or more affinity molecules. One or more semiconductor nanocrystal compounds are linked to one or more affinity molecules to form a semiconductor nanocrystal probe capable of bonding with onemore » or more detectable substances in a material being analyzed, and capable of, in response to exposure to a first energy, providing a second energy. Also described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and treating materials with the probe.« less

Separating semiconductor devices from substrate by etching graded composition release layer disposed between semiconductor devices and substrate including forming protuberances that reduce stiction

DOEpatents

Tauke-Pedretti, Anna; Nielson, Gregory N; Cederberg, Jeffrey G; Cruz-Campa, Jose Luis

2015-05-12

A method includes etching a release layer that is coupled between a plurality of semiconductor devices and a substrate with an etch. The etching includes etching the release layer between the semiconductor devices and the substrate until the semiconductor devices are at least substantially released from the substrate. The etching also includes etching a protuberance in the release layer between each of the semiconductor devices and the substrate. The etch is stopped while the protuberances remain between each of the semiconductor devices and the substrate. The method also includes separating the semiconductor devices from the substrate. Other methods and apparatus are also disclosed.

Method for determining the composition and orientation of III-V {001} semiconductor surfaces

NASA Astrophysics Data System (ADS)

Sung, M. M.; Kim, C.; Rabalais, J. W.

1996-09-01

A method for determining the composition and orientation of III-V {001} semiconductor surfaces is presented and applications are described. The information is obtained from the techniques of time-of-flight scattering and recoiling spectrometry (TOF-SARS), using the composition from azimuth-specific elemental accessibilities (CASEA) method, and low energy electron diffraction (LEED). The azimuth-specific elemental accessibilities (ASEA) are measured experimentally and calculated from the number of accessible atoms in the unit cell and from three-dimensional trajectory simulations using the SARIC program. The in situ analyses identify the 1st-layer elemental species and determine the orientation of the reconstructed surface symmetry elements with respect to the bulk crystallographic directions. This is demonstrated for the III-V {001} compound semiconductor surfaces of GaAs and InAs in the (4 × 2) and (4 × 2) phases and InP in the (4 × 2) phase. The analyses confirm the missing-row-dimer (MRD) structure for GaAs and InAs in which the missing row direction is parallel to the direction of the 1st-layer multimers (dimers) and the missing-row-trimer-dimer (MRTD) structure for InP in which the missing row direction is perpendicular to the direction of the 1st-layer multimers (trimers).

Conductive layer for biaxially oriented semiconductor film growth

DOEpatents

Findikoglu, Alp T.; Matias, Vladimir

2007-10-30

A conductive layer for biaxially oriented semiconductor film growth and a thin film semiconductor structure such as, for example, a photodetector, a photovoltaic cell, or a light emitting diode (LED) that includes a crystallographically oriented semiconducting film disposed on the conductive layer. The thin film semiconductor structure includes: a substrate; a first electrode deposited on the substrate; and a semiconducting layer epitaxially deposited on the first electrode. The first electrode includes a template layer deposited on the substrate and a buffer layer epitaxially deposited on the template layer. The template layer includes a first metal nitride that is electrically conductive and has a rock salt crystal structure, and the buffer layer includes a second metal nitride that is electrically conductive. The semiconducting layer is epitaxially deposited on the buffer layer. A method of making such a thin film semiconductor structure is also described.

Tunable multifunctional topological insulators in ternary Heusler and related compounds

NASA Astrophysics Data System (ADS)

Felser, Claudia

2011-03-01

Recently the quantum spin Hall effect was theoretically predicted and experimentally realized in quantum wells based on the binary semiconductor HgTe. The quantum spin Hall state and topological insulators are new states of quantum matter interesting for both fundamental condensed-matter physics and material science. Many Heusler compounds with C1b structure are ternary semiconductors that are structurally and electronically related to the binary semiconductors. The diversity of Heusler materials opens wide possibilities for tuning the bandgap and setting the desired band inversion by choosing compounds with appropriate hybridization strength (by the lattice parameter) and magnitude of spin--orbit coupling (by the atomic charge). Based on first-principle calculations we demonstrate that around 50 Heusler compounds show band inversion similar to that of HgTe. The topological state in these zero-gap semiconductors can be created by applying strain or by designing an appropriate quantumwell structure, similar to the case of HgTe. Many of these ternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the rare-earth element Ln, which can realize additional properties ranging from superconductivity (for example LaPtBi) to magnetism (for example GdPtBi) and heavy fermion behaviour (for example YbPtBi). These properties can open new research directions in realizing the quantized anomalous Hall effect and topological superconductors. Heusler compounds are similar to a stuffed diamond, correspondingly, it should be possible to find the ``high Z'' equivalent of graphene in a graphite-like structure with 18 valence electrons and with inverted bands. Indeed the ternary compounds, such as LiAuSe and KHgSb with a honeycomb structure of their Au-Se and Hg-Sb layers feature band inversion very similar to HgTe which is a strong precondition for existence of the topological surface states. These materials have a gap at the Fermi energy and are therefore candidates for 3D-topological insulators. Additionally they are centro-symmetric, therefore, it is possible to determine the parity of their wave functions, and hence, their topological character. Surprisingly, the compound KHgSb with the strong SOC is topologically trivial, whereas LiAuSe is found to be a topological non-trivial insulator.

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors

DOE PAGES

Dalal, Shakeel S.; Walters, Diane M.; Lyubimov, Ivan; ...

2015-03-23

Physical vapor deposition is commonly used to prepare organic glasses that serve as the active layers in light-emitting diodes, photovoltaics, and other devices. Recent work has shown that orienting the molecules in such organic semiconductors can significantly enhance device performance. In this paper, we apply a high-throughput characterization scheme to investigate the effect of the substrate temperature (T substrate) on glasses of three organic molecules used as semiconductors. The optical and material properties are evaluated with spectroscopic ellipsometry. We find that molecular orientation in these glasses is continuously tunable and controlled by T substrate/T g, where T g is themore » glass transition temperature. All three molecules can produce highly anisotropic glasses; the dependence of molecular orientation upon substrate temperature is remarkably similar and nearly independent of molecular length. All three compounds form “stable glasses” with high density and thermal stability, and have properties similar to stable glasses prepared from model glass formers. Simulations reproduce the experimental trends and explain molecular orientation in the deposited glasses in terms of the surface properties of the equilibrium liquid. Finally, by showing that organic semiconductors form stable glasses, these results provide an avenue for systematic performance optimization of active layers in organic electronics.« less

Process Challenges in Compound Semiconductors.

DTIC Science & Technology

1988-08-01

dielectric films , and metallization. It became evident during this examination that a major obstacle to the affordable, high-yield manufacture of...in surrounding regions. In both of the structures shown, the curvature of the layers is the characteristic solidification from solution in LPE ...pseudomorphic epitaxial growth is possible only with very thin films in which the structure is strained to match the lattice parameter of the

Single crystal, liquid crystal, and hybrid organic semiconductors

NASA Astrophysics Data System (ADS)

Twieg, Robert J.; Getmanenko, Y.; Lu, Z.; Semyonov, A. N.; Huang, S.; He, P.; Seed, A.; Kiryanov, A.; Ellman, B.; Nene, S.

2003-07-01

The synthesis and characterization of organic semiconductors is being pursued in three primary structure formats: single crystal, liquid crystal and organic-inorganic hybrid. The strategy here is to share common structures, synthesis methods and fabrication techniques across these formats and to utilize common characterization tools such as the time of flight technique. The single crystal efforts concentrate on aromatic and heteroaromatic compounds including simple benzene derivatives and derivatives of the acenes. The structure-property relationships due to incorporation of small substituents and heteroatoms are being examined. Crystals are grown by solution, melt or vapor transport techniques. The liquid crystal studies exploit their self-organizing properties and relative ease of sample preparation. Though calamitic systems tha deliver the largest mobilities are higher order smectics, even some unusual twist grain boundary phases are being studied. We are attempting to synthesize discotic acene derivatives with appropriate substitution patterns to render them mesogenic. The last format being examined is the hybrid organic-inorganic class. Here, layered materials of alternating organic and inorganic composition are designed and synthesized. Typical materials are conjugated aromatic compounds, usually functinalized with an amine or a pyridine and reacted with appropriate reactive metal derivatives to incorporate them into metal oxide or sulfide layers.

Surface passivation process of compound semiconductor material using UV photosulfidation

DOEpatents

Ashby, Carol I. H.

1995-01-01

A method for passivating compound semiconductor surfaces by photolytically disrupting molecular sulfur vapor with ultraviolet radiation to form reactive sulfur which then reacts with and passivates the surface of compound semiconductors.

Field-effect P-N junction

DOEpatents

Regan, William; Zettl, Alexander

2015-05-05

This disclosure provides systems, methods, and apparatus related to field-effect p-n junctions. In one aspect, a device includes an ohmic contact, a semiconductor layer disposed on the ohmic contact, at least one rectifying contact disposed on the semiconductor layer, a gate including a layer disposed on the at least one rectifying contact and the semiconductor layer and a gate contact disposed on the layer. A lateral width of the rectifying contact is less than a semiconductor depletion width of the semiconductor layer. The gate contact is electrically connected to the ohmic contact to create a self-gating feedback loop that is configured to maintain a gate electric field of the gate.

Organic photosensitive cells grown on rough electrode with nano-scale morphology control

DOEpatents

Yang, Fan [Piscataway, NJ; Forrest, Stephen R [Ann Arbor, MI

2011-06-07

An optoelectronic device and a method for fabricating the optoelectronic device includes a first electrode disposed on a substrate, an exposed surface of the first electrode having a root mean square roughness of at least 30 nm and a height variation of at least 200 nm, the first electrode being transparent. A conformal layer of a first organic semiconductor material is deposited onto the first electrode by organic vapor phase deposition, the first organic semiconductor material being a small molecule material. A layer of a second organic semiconductor material is deposited over the conformal layer. At least some of the layer of the second organic semiconductor material directly contacts the conformal layer. A second electrode is deposited over the layer of the second organic semiconductor material. The first organic semiconductor material is of a donor-type or an acceptor-type relative to the second organic semiconductor material, which is of the other material type.

Ultrathin Compound Semiconductor on Insulator Layers for High-Performance Nanoscale Transistors

DTIC Science & Technology

2010-11-11

patterned on the sur- face of the source substrate. The InAs layer was then pattern etched into nano- ribbons using a mixture of citric acid (1 g per ml of...Electron. Dev. 55, 547–556 (2008). 27. DeSalvo, G. C., Kaspi, R. & Bozada, C. A. Citric acid etching of GaAs1-xSbx, Al0.5Ga0.5Sb, and InAs for...interfacial layer formed by thermal oxidation and used for surface passivation is clearly evident. LETTER RESEARCH 1 1 N O V E M B E R 2 0 1 0 | V O L

Numerical investigation of metal-semiconductor-insulator-semiconductor passivated hole contacts based on atomic layer deposited AlO x

NASA Astrophysics Data System (ADS)

Ke, Cangming; Xin, Zheng; Ling, Zhi Peng; Aberle, Armin G.; Stangl, Rolf

2017-08-01

Excellent c-Si tunnel layer surface passivation has been obtained recently in our lab, using atomic layer deposited aluminium oxide (ALD AlO x ) in the tunnel layer regime of 0.9 to 1.5 nm, investigated to be applied for contact passivation. Using the correspondingly measured interface properties, this paper compares the theoretical collection efficiency of a conventional metal-semiconductor (MS) contact on diffused p+ Si to a metal-semiconductor-insulator-semiconductor (MSIS) contact on diffused p+ Si or on undoped n-type c-Si. The influences of (1) the tunnel layer passivation quality at the tunnel oxide interface (Q f and D it), (2) the tunnel layer thickness and the electron and hole tunnelling mass, (3) the tunnel oxide material, and (4) the semiconductor capping layer material properties are investigated numerically by evaluation of solar cell efficiency, open-circuit voltage, and fill factor.

Method for removing semiconductor layers from salt substrates

DOEpatents

Shuskus, Alexander J.; Cowher, Melvyn E.

1985-08-27

A method is described for removing a CVD semiconductor layer from an alkali halide salt substrate following the deposition of the semiconductor layer. The semiconductor-substrate combination is supported on a material such as tungsten which is readily wet by the molten alkali halide. The temperature of the semiconductor-substrate combination is raised to a temperature greater than the melting temperature of the substrate but less than the temperature of the semiconductor and the substrate is melted and removed from the semiconductor by capillary action of the wettable support.

Alpha voltaic batteries and methods thereof

NASA Technical Reports Server (NTRS)

Jenkins, Phillip (Inventor); Scheiman, David (Inventor); Castro, Stephanie (Inventor); Raffaelle, Ryne P. (Inventor); Wilt, David (Inventor); Chubb, Donald (Inventor)

2011-01-01

An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

Controlled growth of larger heterojunction interface area for organic photosensitive devices

DOEpatents

Yang, Fan [Somerset, NJ; Forrest, Stephen R [Ann Arbor, MI

2009-12-29

An optoelectronic device and a method of fabricating a photosensitive optoelectronic device includes depositing a first organic semiconductor material on a first electrode to form a continuous first layer having protrusions, a side of the first layer opposite the first electrode having a surface area at least three times greater than an underlying lateral cross-sectional area; depositing a second organic semiconductor material directly on the first layer to form a discontinuous second layer, portions of the first layer remaining exposed; depositing a third organic semiconductor material directly on the second layer to form a discontinuous third layer, portions of at least the second layer remaining exposed; depositing a fourth organic semiconductor material on the third layer to form a continuous fourth layer, filling any exposed gaps and recesses in the first, second, and third layers; and depositing a second electrode on the fourth layer, wherein at least one of the first electrode and the second electrode is transparent, and the first and third organic semiconductor materials are both of a donor-type or an acceptor-type relative to second and fourth organic semiconductor materials, which are of the other material type.

High efficiency, low cost, thin film silicon solar cell design and method for making

DOEpatents

Sopori, Bhushan L.

2001-01-01

A semiconductor device having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer.

High efficiency low cost thin film silicon solar cell design and method for making

DOEpatents

Sopori, Bhushan L.

1999-01-01

A semiconductor device having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer.

Chemical routes to nanocrystalline and thin-film III-VI and I-III-VI semiconductors

NASA Astrophysics Data System (ADS)

Hollingsworth, Jennifer Ann

1999-11-01

The work encompasses: (1) catalyzed low-temperature, solution-based routes to nano- and microcrystalline III-VI semiconductor powders and (2) spray chemical vapor deposition (spray CVD) of I-III-VI semiconductor thin films. Prior to this work, few, if any, examples existed of chemical catalysis applied to the synthesis of nonmolecular, covalent solids. New crystallization strategies employing catalysts were developed for the regioselective syntheses of orthorhombic InS (beta-InS), the thermodynamic phase, and rhombohedral InS (R-InS), a new, metastable structural isomer. Growth of beta-InS was facilitated by a solvent-suspended, molten-metal flux in a process similar to the SolutionLiquid-Solid (SLS) growth of InP and GaAs fibers and single-crystal whiskers. In contrast, metastable R-InS, having a pseudo-graphitic layered structure, was prepared selectively when the molecular catalyst, benzenethiol, was present in solution and the inorganic "catalyst" (metal flux) was not present. In the absence of any crystal-growth facilitator, metal flux or benzenethiol, amorphous product was obtained under the mild reaction conditions employed (T ≤ 203°C). The inorganic and organic catalysts permitted the regio-selective syntheses of InS and were also successfully applied to the growth of network and layered InxSey compounds, respectively, as well as nanocrystalline In2S3. Extensive microstructural characterization demonstrated that the layered compounds grew as fullerene-like nanostructures and large, colloidal single crystals. Films of the I-III-VI compounds, CuInS2, CuGaS2, and Cu(In,Ga)S 2, were deposited by spray CVD using the known single-source metalorganic precursor, (Ph3P)2CuIn(SEt)4, a new precursor, (Ph3P)2CuGa(SEt)3, and a mixture of the two precursors, respectively. The CulnS2 films exhibited a variety of microstructures from dense and faceted or platelet-like to porous and dendritic. Crystallographic orientations ranged from strongly [112] to strongly [220] oriented. Microstructure, orientation, and growth kinetics were controlled by changing processing parameters: carrier-gas flow rate, substrate temperature, and precursor-solution concentration. Low resistivities (<50 O cm) were associated with [220]-oriented films. All CuInS2 films were approximately stoichiometric and had the desired bandgap (Eg ≅ 1.4 eV) for application as the absorber layer in thin-film photovoltaic devices.

Semiconductor films on flexible iridium substrates

DOEpatents

Goyal, Amit

2005-03-29

A laminate semiconductor article includes a flexible substrate, an optional biaxially textured oxide buffer system on the flexible substrate, a biaxially textured Ir-based buffer layer on the substrate or the buffer system, and an epitaxial layer of a semiconductor. Ir can serve as a substrate with an epitaxial layer of a semiconductor thereon.

Excellent sun-light-driven photocatalytic activity by aurivillius layered perovskites, Bi₅-xLaxTi₃FeO₁₅ (x = 1, 2).

PubMed

Naresh, Gollapally; Mandal, Tapas Kumar

2014-12-10

Aurivillius phase layered perovskites, Bi5-xLaxTi3FeO15 (x = 1, 2) are synthesized by solid-state reaction. The compounds are characterized by powder X-ray diffraction (PXD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis diffuse reflectance (UV-vis DRS), and photoluminescence (PL) spectroscopy. UV-vis DRS data revealed that the compounds are visible light absorbing semiconductors with band gaps ranging from ∼2.0-2.7 eV. Photocatalytic activity studies by Rhodamine B (RhB) degradation under sun-light irradiation showed that these layered oxides are very efficient photocatalysts in mild acidic medium. Scavenger test studies demonstrated that the photogenerated holes and superoxide radicals (O2(•-)) are the active species responsible for RhB degradation over the Aurivillius layered perovskites. Comparison of PL intensity, dye adsorption and ζ-potential suggested that a slow e(-)-h(+) recombination and effective dye adsorption are crucial for the degradation process over these photocatalysts. Moreover, relative positioning of the valence and conduction band edges of the semiconductors, O2/O2(•-), (•)OH/H2O potential and HOMO-LUMO levels of RhB appears to be responsible for making the degradation hole-specific. Photocatalytic cycle tests indicated high stability of the catalysts in the reaction medium without any observable loss of activity. This work shows great potential in developing novel photocatalysts with layered structures for sun-light-driven oxidation and degradation processes largely driven by holes and without any intervention of hydroxyl radicals, which is one of the most common reactive oxygen species (ROS) in many advanced oxidation processes.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

2006-09-05

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. subsequent exposure to excitation energy will excite the semiconductor nanocrystal in the probe causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon [Pinole, CA; Bruchez, Jr., Marcel; Alivisatos, Paul [Oakland, CA

2004-03-02

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Subsequent exposure to excitation energy will excite the semiconductor nanocrystal in the probe, causing the emission of electromagnetic radiation. Further described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

2005-08-09

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Subsequent exposure to excitation energy will excite the semiconductor nanocrystal in the probe causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

2002-01-01

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Subsequent exposure to excitation energy will excite the semiconductor nanocrystal in he probe, causing the emission of electromagnetic radiation. Further described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Room Temperature Hard Radiation Detectors Based on Solid State Compound Semiconductors: An Overview

NASA Astrophysics Data System (ADS)

Mirzaei, Ali; Huh, Jeung-Soo; Kim, Sang Sub; Kim, Hyoun Woo

2018-05-01

Si and Ge single crystals are the most common semiconductor radiation detectors. However, they need to work at cryogenic temperatures to decrease their noise levels. In contrast, compound semiconductors can be operated at room temperature due to their ability to grow compound materials with tunable densities, band gaps and atomic numbers. Highly efficient room temperature hard radiation detectors can be utilized in biomedical diagnostics, nuclear safety and homeland security applications. In this review, we discuss room temperature compound semiconductors. Since the field of radiation detection is broad and a discussion of all compound materials for radiation sensing is impossible, we discuss the most important materials for the detection of hard radiation with a focus on binary heavy metal semiconductors and ternary and quaternary chalcogenide compounds.

Light emitting diode with porous SiC substrate and method for fabricating

DOEpatents

Li, Ting; Ibbetson, James; Keller, Bernd

2005-12-06

A method and apparatus for forming a porous layer on the surface of a semiconductor material wherein an electrolyte is provided and is placed in contact with one or more surfaces of a layer of semiconductor material. The electrolyte is heated and a bias is introduced across said electrolyte and the semiconductor material causing a current to flow between the electrolyte and the semiconductor material. The current forms a porous layer on the one or more surfaces of the semiconductor material in contact with the electrolyte. The semiconductor material with its porous layer can serve as a substrate for a light emitter. A semiconductor emission region can be formed on the substrate. The emission region is capable of emitting light omnidirectionally in response to a bias, with the porous layer enhancing extraction of the emitting region light passing through the substrate.

Photovoltaic healing of non-uniformities in semiconductor devices

DOEpatents

Karpov, Victor G.; Roussillon, Yann; Shvydka, Diana; Compaan, Alvin D.; Giolando, Dean M.

2006-08-29

A method of making a photovoltaic device using light energy and a solution to normalize electric potential variations in the device. A semiconductor layer having nonuniformities comprising areas of aberrant electric potential deviating from the electric potential of the top surface of the semiconductor is deposited onto a substrate layer. A solution containing an electrolyte, at least one bonding material, and positive and negative ions is applied over the top surface of the semiconductor. Light energy is applied to generate photovoltage in the semiconductor, causing a redistribution of the ions and the bonding material to the areas of aberrant electric potential. The bonding material selectively bonds to the nonuniformities in a manner such that the electric potential of the nonuniformities is normalized relative to the electric potential of the top surface of the semiconductor layer. A conductive electrode layer is then deposited over the top surface of the semiconductor layer.

Growth of coincident site lattice matched semiconductor layers and devices on crystalline substrates

DOEpatents

Norman, Andrew G; Ptak, Aaron J

2013-08-13

Methods of fabricating a semiconductor layer or device and said devices are disclosed. The methods include but are not limited to providing a substrate having a crystalline surface with a known lattice parameter (a). The method further includes growing a crystalline semiconductor layer on the crystalline substrate surface by coincident site lattice matched epitaxy, without any buffer layer between the crystalline semiconductor layer and the crystalline surface of the substrate. The crystalline semiconductor layer will be prepared to have a lattice parameter (a') that is related to the substrate lattice parameter (a). The lattice parameter (a') maybe related to the lattice parameter (a) by a scaling factor derived from a geometric relationship between the respective crystal lattices.

Intermediate-band photosensitive device with quantum dots embedded in energy fence barrier

DOEpatents

Forrest, Stephen R.; Wei, Guodan

2010-07-06

A plurality of layers of a first semiconductor material and a plurality of dots-in-a-fence barriers disposed in a stack between a first electrode and a second electrode. Each dots-in-a-fence barrier consists essentially of a plurality of quantum dots of a second semiconductor material embedded between and in direct contact with two layers of a third semiconductor material. Wave functions of the quantum dots overlap as at least one intermediate band. The layers of the third semiconductor material are arranged as tunneling barriers to require a first electron and/or a first hole in a layer of the first material to perform quantum mechanical tunneling to reach the second material within a respective quantum dot, and to require a second electron and/or a second hole in a layer of the first semiconductor material to perform quantum mechanical tunneling to reach another layer of the first semiconductor material.

Energy resolution in semiconductor gamma radiation detectors using heterojunctions and methods of use and preparation thereof

DOEpatents

Nikolic, Rebecca J.; Conway, Adam M.; Nelson, Art J.; Payne, Stephen A.

2012-09-04

In one embodiment, a system comprises a semiconductor gamma detector material and a hole blocking layer adjacent the gamma detector material, the hole blocking layer resisting passage of holes therethrough. In another embodiment, a system comprises a semiconductor gamma detector material, and an electron blocking layer adjacent the gamma detector material, the electron blocking layer resisting passage of electrons therethrough, wherein the electron blocking layer comprises undoped HgCdTe. In another embodiment, a method comprises forming a hole blocking layer adjacent a semiconductor gamma detector material, the hole blocking layer resisting passage of holes therethrough. Additional systems and methods are also presented.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon [Pinole, CA; Bruchez, Jr., Marcel; Alivisatos, Paul [Oakland, CA

2008-01-01

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) an affinity molecule linked to the semiconductor nanocrystal. The semiconductor nanocrystal is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Exposure of the semiconductor nanocrystal to excitation energy will excite the semiconductor nanocrystal causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Lattice matched semiconductor growth on crystalline metallic substrates

DOEpatents

Norman, Andrew G; Ptak, Aaron J; McMahon, William E

2013-11-05

Methods of fabricating a semiconductor layer or device and said devices are disclosed. The methods include but are not limited to providing a metal or metal alloy substrate having a crystalline surface with a known lattice parameter (a). The methods further include growing a crystalline semiconductor alloy layer on the crystalline substrate surface by coincident site lattice matched epitaxy. The semiconductor layer may be grown without any buffer layer between the alloy and the crystalline surface of the substrate. The semiconductor alloy may be prepared to have a lattice parameter (a') that is related to the lattice parameter (a). The semiconductor alloy may further be prepared to have a selected band gap.

High efficiency low cost thin film silicon solar cell design and method for making

DOEpatents

Sopori, B.L.

1999-04-27

A semiconductor device is described having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer. 9 figs.

Methods for forming thin-film heterojunction solar cells from I-III-VI{sub 2}

DOEpatents

Mickelsen, R.A.; Chen, W.S.

1985-08-13

An improved thin-film, large area solar cell, and methods for forming the same are disclosed, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI{sub 2} chalcopyrite ternary materials which is vacuum deposited in a thin ``composition-graded`` layer ranging from on the order of about 2.5 microns to about 5.0 microns ({approx_equal}2.5 {mu}m to {approx_equal}5.0 {mu}m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii) a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion occurs (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer. 16 figs.

Methods for forming thin-film heterojunction solar cells from I-III-VI[sub 2

DOEpatents

Mickelsen, R.A.; Chen, W.S.

1982-06-15

An improved thin-film, large area solar cell, and methods for forming the same are disclosed, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (1) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI[sub 2] chalcopyrite ternary materials which is vacuum deposited in a thin composition-graded'' layer ranging from on the order of about 2.5 microns to about 5.0 microns ([approx equal]2.5[mu]m to [approx equal]5.0[mu]m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (2), a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, is allowed.

Electroluminescent devices formed using semiconductor nanocrystals as an electron transport media and method of making such electroluminescent devices

DOEpatents

Alivisatos, A. Paul; Colvin, Vickie

1996-01-01

An electroluminescent device is described, as well as a method of making same, wherein the device is characterized by a semiconductor nanocrystal electron transport layer capable of emitting visible light in response to a voltage applied to the device. The wavelength of the light emitted by the device may be changed by changing either the size or the type of semiconductor nanocrystals used in forming the electron transport layer. In a preferred embodiment the device is further characterized by the capability of emitting visible light of varying wavelengths in response to changes in the voltage applied to the device. The device comprises a hole processing structure capable of injecting and transporting holes, and usually comprising a hole injecting layer and a hole transporting layer; an electron transport layer in contact with the hole processing structure and comprising one or more layers of semiconductor nanocrystals; and an electron injecting layer in contact with the electron transport layer for injecting electrons into the electron transport layer. The capability of emitting visible light of various wavelengths is principally based on the variations in voltage applied thereto, but the type of semiconductor nanocrystals used and the size of the semiconductor nanocrystals in the layers of semiconductor nanometer crystals may also play a role in color change, in combination with the change in voltage.

Tunnel barrier schottky

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chu, Rongming; Cao, Yu; Li, Zijian

2018-02-20

A diode includes: a semiconductor substrate; a cathode metal layer contacting a bottom of the substrate; a semiconductor drift layer on the substrate; a graded aluminum gallium nitride (AlGaN) semiconductor barrier layer on the drift layer and having a larger bandgap than the drift layer, the barrier layer having a top surface and a bottom surface between the drift layer and the top surface, the barrier layer having an increasing aluminum composition from the bottom surface to the top surface; and an anode metal layer directly contacting the top surface of the barrier layer.

New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

NASA Astrophysics Data System (ADS)

Xiong, Kecai; Liu, Wei; Teat, Simon J.; An, Litao; Wang, Hao; Emge, Thomas J.; Li, Jing

2015-10-01

Two new hybrid lead halides (H2BDA)[PbI4] (1) (H2BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI3] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively.

Voltage-matched, monolithic, multi-band-gap devices

DOEpatents

Wanlass, Mark W.; Mascarenhas, Angelo

2006-08-22

Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a sting of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.

Voltage-Matched, Monolithic, Multi-Band-Gap Devices

DOEpatents

Wanlass, M. W.; Mascarenhas, A.

2006-08-22

Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a string of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.

Photovoltaic devices comprising zinc stannate buffer layer and method for making

DOEpatents

Wu, Xuanzhi; Sheldon, Peter; Coutts, Timothy J.

2001-01-01

A photovoltaic device has a buffer layer zinc stannate Zn.sub.2 SnO.sub.4 disposed between the semiconductor junction structure and the transparent conducting oxide (TCO) layer to prevent formation of localized junctions with the TCO through a thin window semiconductor layer, to prevent shunting through etched grain boundaries of semiconductors, and to relieve stresses and improve adhesion between these layers.

Large-area, laterally-grown epitaxial semiconductor layers

DOEpatents

Han, Jung; Song, Jie; Chen, Danti

2017-07-18

Structures and methods for confined lateral-guided growth of a large-area semiconductor layer on an insulating layer are described. The semiconductor layer may be formed by heteroepitaxial growth from a selective growth area in a vertically-confined, lateral-growth guiding structure. Lateral-growth guiding structures may be formed in arrays over a region of a substrate, so as to cover a majority of the substrate region with laterally-grown epitaxial semiconductor tiles. Quality regions of low-defect, stress-free GaN may be grown on silicon.

Fabrication of polycrystalline solar cells on low-cost substrates

NASA Technical Reports Server (NTRS)

Chu, T. L. (Inventor)

1976-01-01

A new method of producing p-n junction semiconductors for solar cells was described; the principal objective of this investigation is to reduce production costs significantly by depositing polycrystalline silicon on a relatively cheap substrate such as metallurgical-grade silicon, graphite, or steel. The silicon layer contains appropriate dopants, and the substrates are coated with a diffusion barrier of silica, borosilicate, phosphosilicate, or mixtures of these compounds.

340 Ghz Multipixel Transceiver

NASA Technical Reports Server (NTRS)

Chattopadhyay, Goutam (Inventor); Cooper, Ken B. (Inventor); Decrossas, Emmanuel (Inventor); Gill, John J. (Inventor); Jung-Kubiak, Cecile (Inventor); Lee, Choonsup (Inventor); Lin, Robert (Inventor); Mehdi, Imran (Inventor); Peralta, Alejandro (Inventor); Reck, Theodore (Inventor)

2017-01-01

A multi-pixel terahertz transceiver is constructed using a stack of semiconductor layers that communicate using vias defined within the semiconductor layers. By using a stack of semiconductor layers, the various electrical functions of each layer can be tested easily without having to assemble the entire transceiver. In addition, the design allows the production of a transceiver having pixels set 10 mm apart.

Back contact buffer layer for thin-film solar cells

DOEpatents

Compaan, Alvin D.; Plotnikov, Victor V.

2014-09-09

A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

Methods for forming thin-film heterojunction solar cells from I-III-VI.sub. 2

DOEpatents

Mickelsen, Reid A.; Chen, Wen S.

1982-01-01

An improved thin-film, large area solar cell, and methods for forming the same, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI.sub.2 chalcopyrite ternary materials which is vacuum deposited in a thin "composition-graded" layer ranging from on the order of about 2.5 microns to about 5.0 microns (.congruent.2.5.mu.m to .congruent.5.0.mu.m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii), a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, causes the transient n-type material in The Government has rights in this invention pursuant to Contract No. EG-77-C-01-4042, Subcontract No. XJ-9-8021-1 awarded by the U.S. Department of Energy.

Methods for forming thin-film heterojunction solar cells from I-III-VI.sub. 2

DOEpatents

Mickelsen, Reid A [Bellevue, WA; Chen, Wen S [Seattle, WA

1985-08-13

An improved thin-film, large area solar cell, and methods for forming the same, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI.sub.2 chalcopyrite ternary materials which is vacuum deposited in a thin "composition-graded" layer ranging from on the order ot about 2.5 microns to about 5.0 microns (.congruent.2.5 .mu.m to .congruent.5.0 .mu.m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii), a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, causes the The Government has rights in this invention pursuant to Contract No. EG-77-C-01-4042, Subcontract No. XJ-9-8021-1 awarded by the U.S. Department of Energy.

Methods of producing free-standing semiconductors using sacrificial buffer layers and recyclable substrates

DOEpatents

Ptak, Aaron Joseph; Lin, Yong; Norman, Andrew; Alberi, Kirstin

2015-05-26

A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices. The low-defect density semiconductor materials produced using this method result in the enhanced performance of the semiconductor devices that incorporate the semiconductor materials.

Use of layer strains in strained-layer superlattices to make devices for operation in new wavelength ranges, E. G. , InAsSb at 8 to 12. mu. m. [InAs/sub 1-x/Sb/sub x/

DOEpatents

Osbourn, G.C.

1983-10-06

An intrinsic semiconductor electro-optical device comprises a p-n junction intrinsically responsive, when cooled, to electromagnetic radiation in the wavelength range of 8 to 12 ..mu..m. This radiation responsive p-n junction comprises a strained-layer superlattice (SLS) of alternating layers of two different III-V semiconductors. The lattice constants of the two semiconductors are mismatched, whereby a total strain is imposed on each pair of alternating semiconductor layers in the SLS structure, the proportion of the total strain which acts on each layer of the pair being proportional to the ratio of the layer thicknesses of each layer in the pair.

Plasmon absorption modulator systems and methods

DOEpatents

Kekatpure, Rohan Deodatta; Davids, Paul

2014-07-15

Plasmon absorption modulator systems and methods are disclosed. A plasmon absorption modulator system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and a metal layer formed on a top surface of the stack of quantum well layers. A method for modulating plasmonic current includes enabling propagation of the plasmonic current along a metal layer, and applying a voltage across the stack of quantum well layers to cause absorption of a portion of energy of the plasmonic current by the stack of quantum well layers. A metamaterial switching system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and at least one metamaterial structure formed on a top surface of the stack of quantum well layers.

Isotope engineering of van der Waals interactions in hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Vuong, T. Q. P.; Liu, S.; van der Lee, A.; Cuscó, R.; Artús, L.; Michel, T.; Valvin, P.; Edgar, J. H.; Cassabois, G.; Gil, B.

2018-02-01

Hexagonal boron nitride is a model lamellar compound where weak, non-local van der Waals interactions ensure the vertical stacking of two-dimensional honeycomb lattices made of strongly bound boron and nitrogen atoms. We study the isotope engineering of lamellar compounds by synthesizing hexagonal boron nitride crystals with nearly pure boron isotopes (10B and 11B) compared to those with the natural distribution of boron (20 at% 10B and 80 at% 11B). On the one hand, as with standard semiconductors, both the phonon energy and electronic bandgap varied with the boron isotope mass, the latter due to the quantum effect of zero-point renormalization. On the other hand, temperature-dependent experiments focusing on the shear and breathing motions of adjacent layers revealed the specificity of isotope engineering in a layered material, with a modification of the van der Waals interactions upon isotope purification. The electron density distribution is more diffuse between adjacent layers in 10BN than in 11BN crystals. Our results open perspectives in understanding and controlling van der Waals bonding in layered materials.

Isotope engineering of van der Waals interactions in hexagonal boron nitride.

PubMed

Vuong, T Q P; Liu, S; Van der Lee, A; Cuscó, R; Artús, L; Michel, T; Valvin, P; Edgar, J H; Cassabois, G; Gil, B

2018-02-01

Hexagonal boron nitride is a model lamellar compound where weak, non-local van der Waals interactions ensure the vertical stacking of two-dimensional honeycomb lattices made of strongly bound boron and nitrogen atoms. We study the isotope engineering of lamellar compounds by synthesizing hexagonal boron nitride crystals with nearly pure boron isotopes ( 10 B and 11 B) compared to those with the natural distribution of boron (20 at% 10 B and 80 at% 11 B). On the one hand, as with standard semiconductors, both the phonon energy and electronic bandgap varied with the boron isotope mass, the latter due to the quantum effect of zero-point renormalization. On the other hand, temperature-dependent experiments focusing on the shear and breathing motions of adjacent layers revealed the specificity of isotope engineering in a layered material, with a modification of the van der Waals interactions upon isotope purification. The electron density distribution is more diffuse between adjacent layers in 10 BN than in 11 BN crystals. Our results open perspectives in understanding and controlling van der Waals bonding in layered materials.

Surface preparation of substances for continuous convective assembly of fine particles

DOEpatents

Rossi, Robert

2003-01-01

A method for producing periodic nanometer-scale arrays of metal or semiconductor junctions on a clean semiconductor substrate surface is provided comprising the steps of: etching the substrate surface to make it hydrophilic, forming, under an inert atmosphere, a crystalline colloid layer on the substrate surface, depositing a metal or semiconductor material through the colloid layer onto the surface of the substrate, and removing the colloid from the substrate surface. The colloid layer is grown on the clean semiconductor surface by withdrawing the semiconductor substrate from a sol of colloid particles.

[CH(3)(CH(2))(11)NH(3)]SnI(3): a hybrid semiconductor with MoO(3)-type tin(II) iodide layers.

PubMed

Xu, Zhengtao; Mitzi, David B

2003-10-20

The organic-inorganic hybrid [CH(3)(CH(2))(11)NH(3)]SnI(3) presents a lamellar structure with a Sn-I framework isotypic to that of MoO(3). The SnI(3)(-) layer consists of edge and corner-sharing SnI(6) octahedra in which one of the six Sn-I bonds is distinctly elongated (e.g., 3.62 A), indicating lone-pair stereoactivity for the Sn(II) atom. The overall electronic character remains comparable with that of the well-studied SnI(4)(2)(-)-based perovskite semiconductors, such as [CH(3)(CH(2))(11)NH(3)](2)SnI(4), with a red-shifted and broadened exciton peak associated with the band gap, apparently due to the increased dimensionality of the Sn-I framework. The title compound offers, aside from the hybrid perovskites, a new type of solution-processable Sn-I network for potential applications in semiconductive devices.

Atomic Scale Dynamics of Contact Formation in the Cross-Section of InGaAs Nanowire Channels

DOE PAGES

Chen, Renjie; Jungjohann, Katherine L.; Mook, William M.; ...

2017-03-23

In the alloyed and compound contacts between metal and semiconductor transistor channels we see that they enable self-aligned gate processes which play a significant role in transistor scaling. At nanoscale dimensions and for nanowire channels, prior experiments focused on reactions along the channel length, but the early stage of reaction in their cross sections remains unknown. We report on the dynamics of the solid-state reaction between metal (Ni) and semiconductor (In 0.53Ga 0.47As), along the cross-section of nanowires that are 15 nm in width. Unlike planar structures where crystalline nickelide readily forms at conventional, low alloying temperatures, nanowires exhibit amore » solid-state amorphization step that can undergo a crystal regrowth step at elevated temperatures. Here, we capture the layer-by-layer reaction mechanism and growth rate anisotropy using in situ transmission electron microscopy (TEM). Our kinetic model depicts this new, in-plane contact formation which could pave the way for engineered nanoscale transistors.« less

Thin-film solar cell fabricated on a flexible metallic substrate

DOEpatents

Tuttle, John R.; Noufi, Rommel; Hasoon, Falah S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

DOEpatents

Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Electroluminescence color tuning between green and red from metal-oxide-semiconductor devices fabricated by spin-coating of rare-earth (terbium + europium) organic compounds on silicon

NASA Astrophysics Data System (ADS)

Matsuda, Toshihiro; Hattori, Fumihiro; Iwata, Hideyuki; Ohzone, Takashi

2018-04-01

Color tunable electroluminescence (EL) from metal-oxide-semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insulator layer. The EL spectra had only peaks corresponding to the intrashell Tb3+/Eu3+ transitions in the spectral range from green to red, and the intensity ratio of the peaks was appropriately tuned using the appropriate Eu/Tb ratios in liquid sources. Consequently, the EL emission colors linearly changed from yellowish green to yellowish orange and eventually to reddish orange on the CIE chromaticity diagram. The gate current +I G current also affected the EL colors for the medium-Eu/Tb-ratio device. The structure of the surface insulator films analyzed by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS) has four layers, namely, (Tb4O7 + Eu2O3), [Tb4O7 + Eu2O3 + (Tb/Eu/Ba)SiO x ], (Tb/Eu/Ba)SiO x , and SiO x -rich oxide. The EL mechanism proposed is that electrons injected from the Si substrate into the SiO x -rich oxide and Tb/Eu/Ba-silicate layers become hot electrons accelerated in a high electric field, and then these hot electrons excite Tb3+ and Eu3+ ions in the Tb4O7/Eu2O3 layers resulting in EL emission from Tb3+ and Eu3+ intrashell transitions.

Interconnected semiconductor devices

DOEpatents

Grimmer, Derrick P.; Paulson, Kenneth R.; Gilbert, James R.

1990-10-23

Semiconductor layer and conductive layer formed on a flexible substrate, divided into individual devices and interconnected with one another in series by interconnection layers and penetrating terminals.

Thermally robust semiconductor optical amplifiers and laser diodes

DOEpatents

Dijaili, Sol P.; Patterson, Frank G.; Walker, Jeffrey D.; Deri, Robert J.; Petersen, Holly; Goward, William

2002-01-01

A highly heat conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient or heat sink. However, the semiconductor material itself should be as temperature insensitive as possible and therefore the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, e.g., a ridge waveguide. The second and most important function, as it relates to this invention, is that it provides a significantly higher thermal conductivity than the semiconductor material, which is the principal material in the fabrication of various optoelectronic devices.

Organo Luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

1999-01-01

A luminescent semiconductor nanocrystal compound is described which is capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation (luminescing) in a narrow wavelength band and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source (of narrow or broad bandwidth) or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The luminescent semiconductor nanocrystal compound is linked to an affinity molecule to form an organo luminescent semiconductor nanocrystal probe capable of bonding with a detectable substance in a material being analyzed, and capable of emitting electromagnetic radiation in a narrow wavelength band and/or absorbing, scattering, or diffracting energy when excited by an electromagnetic radiation source (of narrow or broad bandwidth) or a particle beam. The probe is stable to repeated exposure to light in the presence of oxygen and/or other radicals. Further described is a process for making the luminescent semiconductor nanocrystal compound and for making the organo luminescent semiconductor nanocrystal probe comprising the luminescent semiconductor nanocrystal compound linked to an affinity molecule capable of bonding to a detectable substance. A process is also described for using the probe to determine the presence of a detectable substance in a material.

Unitary lens semiconductor device

DOEpatents

Lear, Kevin L.

1997-01-01

A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

Anisotropic dependence of the magnetic transition on uniaxial pressure in the Kondo semiconductors Ce T2A l10 (T =Ru and Os)

NASA Astrophysics Data System (ADS)

Hayashi, K.; Umeo, K.; Takeuchi, T.; Kawabata, J.; Muro, Y.; Takabatake, T.

2017-12-01

We have measured the strain, magnetization, and specific heat of the antiferromagnetic (AFM) Kondo semiconductors Ce T2A l10 (T =Ru and Os) under uniaxial pressures applied along the orthorhombic axes. We found a linear dependence of TN on the b -axis parameter for both compounds under uniaxial pressure P ∥b and hydrostatic pressure. This relation indicates that the distance between the Ce-T layers along the b axis is the key structural parameter determining TN. Furthermore, the pressure dependence of the spin-flop transition field indicates that Ce-Ce interchain interactions stabilize the AFM state with the ordered moments pointing to the c axis.

In situ growth of metal particles on 3D urchin-like WO3 nanostructures.

PubMed

Xi, Guangcheng; Ye, Jinhua; Ma, Qiang; Su, Ning; Bai, Hua; Wang, Chao

2012-04-18

Metal/semiconductor hybrid materials of various sizes and morphologies have many applications in areas such as catalysis and sensing. Various organic agents are necessary to stabilize metal nanoparticles during synthesis, which leads to a layer of organic compounds present at the interfaces between the metal particles and the semiconductor supports. Generally, high-temperature oxidative treatment is used to remove the organics, which can extensively change the size and morphology of the particles, in turn altering their activity. Here we report a facile method for direct growth of noble-metal particles on WO(3) through an in situ redox reaction between weakly reductive WO(2.72) and oxidative metal salts in aqueous solution. This synthetic strategy has the advantages that it takes place in one step and requires no foreign reducing agents, stabilizing agents, or pretreatment of the precursors, making it a practical method for the controlled synthesis of metal/semiconductor hybrid nanomaterials. This synthetic method may open up a new way to develop metal-nanoparticle-loaded semiconductor composites. © 2012 American Chemical Society

Two Types of 2D Layered Iodoargentates Based on Trimeric [Ag3I7] Secondary Building Units and Hexameric [Ag6I12] Ternary Building Units: Syntheses, Crystal Structures, and Efficient Visible Light Responding Photocatalytic Properties.

PubMed

Lei, Xiao-Wu; Yue, Cheng-Yang; Zhao, Jian-Qiang; Han, Yong-Fang; Yang, Jiang-Tao; Meng, Rong-Rong; Gao, Chuan-Sheng; Ding, Hao; Wang, Chun-Yan; Chen, Wan-Dong; Hong, Mao-Chun

2015-11-16

With mixed transition-metal-complex, alkali-metal, or organic cations as structure-directing agents, a series of novel two-dimensional (2D) layered inorganic-organic hybrid iodoargentates, namely, Kx[TM(2,2-bipy)3]2Ag6I11 (TM = Mn (1), Fe (2), Co (3), Ni (4), Zn (5); x = 0.89-1) and [(Ni(2,2-bipy)3][H-2,2-bipy]Ag3I6 (6), have been solvothermally synthesized and structurally characterized. All the title compounds feature 2D microporous layers composed by [Ag3I7] secondary building units based on AgI4 tetrahedra. Differently, the [Ag3I7] trimers are directly interconnected via corner-sharing to form the 2D [Ag6I11](5-) layer in compounds 1-5, whereas two neighboring [Ag3I7] trimers are initially condensed into a hexameric [Ag6I12] ternary building unit as a new node, which further self-assembles, leading to the 2D [Ag6I10](4-) layer in compound 6. The UV-vis diffuse-reflectance measurements reveal that all the compounds possess proper semiconductor behaviors with tunable band gaps of 1.66-2.75 eV, which lead to highly efficient photocatalytic degradation activities over organic pollutants under visible light irradiation compared to that of N-dotted P25. Interestingly, all the samples feature distinct photodegradative speeds at the same reaction conditions, and compound 1 features the highest photocatalytic activity among the title phases. The luminescence properties, band structures, and thermal stabilities were also studied.

Structure and magnetic properties of oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) with Fe2O square planar layers representing an antiferromagnetic checkerboard spin lattice.

PubMed

Kabbour, Houria; Janod, Etienne; Corraze, Benoît; Danot, Michel; Lee, Changhoon; Whangbo, Myung-Hwan; Cario, Laurent

2008-07-02

The oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se), which contain Fe2O square planar layers of the anti-CuO2 type, were predicted using a modular assembly of layered secondary building units and subsequently synthesized. The physical properties of these compounds were characterized using magnetic susceptibility, electrical resistivity, specific heat, (57)Fe Mossbauer, and powder neutron diffraction measurements and also by estimating their exchange interactions on the basis of first-principles density functional theory electronic structure calculations. These compounds are magnetic semiconductors that undergo a long-range antiferromagnetic ordering below 83.6-106.2 K, and their magnetic properties are well-described by a two-dimensional Ising model. The dominant antiferromagnetic spin exchange interaction between S = 2 Fe(2+) ions occurs through corner-sharing Fe-O-Fe bridges. Moreover, the calculated spin exchange interactions show that the A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) compounds represent a rare example of a frustrated antiferromagnetic checkerboard lattice.

Method for depositing high-quality microcrystalline semiconductor materials

DOEpatents

Guha, Subhendu [Bloomfield Hills, MI; Yang, Chi C [Troy, MI; Yan, Baojie [Rochester Hills, MI

2011-03-08

A process for the plasma deposition of a layer of a microcrystalline semiconductor material is carried out by energizing a process gas which includes a precursor of the semiconductor material and a diluent with electromagnetic energy so as to create a plasma therefrom. The plasma deposits a layer of the microcrystalline semiconductor material onto the substrate. The concentration of the diluent in the process gas is varied as a function of the thickness of the layer of microcrystalline semiconductor material which has been deposited. Also disclosed is the use of the process for the preparation of an N-I-P type photovoltaic device.

Unitary lens semiconductor device

DOEpatents

Lear, K.L.

1997-05-27

A unitary lens semiconductor device and method are disclosed. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors. 9 figs.

Insertion of Ag atoms into layered MoO{sub 3} via a template route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Ke, E-mail: shaoke@szu.edu.cn; Wang, Hao

2012-11-15

Graphical abstract: PVP–Ag{sup +} complex self-assembled with inorganic (Mo{sub x}O{sub y}){sub ∞}{sup n−} chains into a layered hybrid, in which the PVP–Ag complex was intercalated between the (Mo{sub x}O{sub y}){sub ∞}{sup n−} layers. Calcinations of this hybrid at 500 °C lead to formation of Ag/MoO{sub 3} nanohybrid. By this method we have successfully inserted Ag atoms into the semiconductor MoO{sub 3} lattice. Display Omitted Highlights: ► We fabricated a PVP–Ag/polyoxomolybdate layered hybrid via in situ self-assembly. ► The PVP–Ag complex has been inserted between the molybdenum oxide layers. ► This layered hybrid transformed into Ag/MoO{sub 3} nanocomposite after calcinations. ►more » HR-TEM images show that Ag atoms of about 1 nm have been inserted in the MoO{sub 3} layers. -- Abstract: We report insertion of Ag atoms into layered MoO{sub 3} via an in situ template route. PVP–Ag{sup +} complex self-assembled with inorganic (Mo{sub x}O{sub y}){sub ∞}{sup n−} chains into a layered hybrid, in which the PVP–Ag complex was intercalated between the (Mo{sub x}O{sub y}){sub ∞}{sup n−} layers. Calcinations of this hybrid at 500 °C lead to formation of Ag/MoO{sub 3} hybrid, in which Ag nanoparticles of about 1 nm have been inserted between the MoO{sub 3} layers. By this method pillared MoO{sub 3} has been obtained very easily. We believe that this research opens new routes to fabricate novel intercalation compounds and metal/semiconductor nanohybrids via an efficient and green route.« less

Low temperature production of large-grain polycrystalline semiconductors

DOEpatents

Naseem, Hameed A [Fayetteville, AR; Albarghouti, Marwan [Loudonville, NY

2007-04-10

An oxide or nitride layer is provided on an amorphous semiconductor layer prior to performing metal-induced crystallization of the semiconductor layer. The oxide or nitride layer facilitates conversion of the amorphous material into large grain polycrystalline material. Hence, a native silicon dioxide layer provided on hydrogenated amorphous silicon (a-Si:H), followed by deposited Al permits induced crystallization at temperatures far below the solid phase crystallization temperature of a-Si. Solar cells and thin film transistors can be prepared using this method.

Reactive codoping of GaAlInP compound semiconductors

DOEpatents

Hanna, Mark Cooper [Boulder, CO; Reedy, Robert [Golden, CO

2008-02-12

A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

Method for growing low defect, high purity crystalline layers utilizing lateral overgrowth of a patterned mask

NASA Technical Reports Server (NTRS)

Morrison, Andrew D. (Inventor); Daud, Taher (Inventor)

1986-01-01

A method for growing a high purity, low defect layer of semiconductor is described. This method involves depositing a patterned mask of a material impervious to impurities of the semiconductor on a surface of a blank. When a layer of semiconductor is grown on the mask, the semiconductor will first grow from the surface portions exposed by the openings in the mask and will bridge the connecting portions of the mask to form a continuous layer having improved purity, since only the portions overlying the openings are exposed to defects and impurities. The process can be iterated and the mask translated to further improve the quality of grown layers.

Growth and photoluminescence study of several single crystal segments relevant to monolithic semiconductor cascade solar cells

NASA Astrophysics Data System (ADS)

Sillmon, Roger S.; Schreiner, Anton F.; Timmons, Michael

1983-09-01

Several representative single crystal stacked layers of III-V compound and alloy semiconductors were grown which are spatial regions relevant to a monolithic cascade solar cell, including the substrate, n-GaAs(Si), which was pre-growth heat treated in H 2(g) prior to its use. These structures were then studied by cryogenic laser excited photoluminescence (PL), and the substrate portion was explored in a depth profiling mode. Within the forbidden band gap region up to seven recombinations were observed and identified for undoped GaAs layers or the GaAs(Si) substrate, and several other PL recombinations were observed for undoped Al xGa 1- xAs and Al yGa 1- ySb zAs 1- z layers. In addition to the valence and conduction bands, these optical bands are also associa ted with the presence of C Ga, Si Ga, Si As, Cu Ga, V As, V Ga and vacancy-impurity complexes involving several of these defect types even in the absence of intentional doping. The findings also relate to problems of self-compensation and type inversion, so that the need for growth modifications is indicated.

Complementary junction heterostructure field-effect transistor

DOEpatents

Baca, Albert G.; Drummond, Timothy J.; Robertson, Perry J.; Zipperian, Thomas E.

1995-01-01

A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits.

Complementary junction heterostructure field-effect transistor

DOEpatents

Baca, A.G.; Drummond, T.J.; Robertson, P.J.; Zipperian, T.E.

1995-12-26

A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits. 10 figs.

Laser pumping of thyristors for fast high current rise-times

DOEpatents

Glidden, Steven C.; Sanders, Howard D.

2013-06-11

An optically triggered semiconductor switch includes an anode metallization layer; a cathode metallization layer; a semiconductor between the anode metallization layer and the cathode metallization layer and a photon source. The semiconductor includes at least four layers of alternating doping in the form P-N-P-N, in which an outer layer adjacent to the anode metallization layer forms an anode and an outer layer adjacent the cathode metallization layer forms a cathode and in which the anode metallization layer has a window pattern of optically transparent material exposing the anode layer to light. The photon source emits light having a wavelength, with the light from the photon source being configured to match the window pattern of the anode metallization layer.

Optical devices featuring textured semiconductor layers

DOEpatents

Moustakas, Theodore D [Dover, MA; Cabalu, Jasper S [Cary, NC

2011-10-11

A semiconductor sensor, solar cell or emitter, or a precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate. The textured layers enhance light extraction or absorption. Texturing in the region of multiple quantum wells greatly enhances internal quantum efficiency if the semiconductor is polar and the quantum wells are grown along the polar direction. Electroluminescence of LEDs of the invention is dichromatic, and results in variable color LEDs, including white LEDs, without the use of phosphor.

Optical devices featuring textured semiconductor layers

DOEpatents

Moustakas, Theodore D [Dover, MA; Cabalu, Jasper S [Cary, NC

2012-08-07

A semiconductor sensor, solar cell or emitter, or a precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate. The textured layers enhance light extraction or absorption. Texturing in the region of multiple quantum wells greatly enhances internal quantum efficiency if the semiconductor is polar and the quantum wells are grown along the polar direction. Electroluminescence of LEDs of the invention is dichromatic, and results in variable color LEDs, including white LEDs, without the use of phosphor.

Back-side readout semiconductor photomultiplier

DOEpatents

Choong, Woon-Seng; Holland, Stephen E

2014-05-20

This disclosure provides systems, methods, and apparatus related to semiconductor photomultipliers. In one aspect, a device includes a p-type semiconductor substrate, the p-type semiconductor substrate having a first side and a second side, the first side of the p-type semiconductor substrate defining a recess, and the second side of the p-type semiconductor substrate being doped with n-type ions. A conductive material is disposed in the recess. A p-type epitaxial layer is disposed on the second side of the p-type semiconductor substrate. The p-type epitaxial layer includes a first region proximate the p-type semiconductor substrate, the first region being implanted with p-type ions at a higher doping level than the p-type epitaxial layer, and a second region disposed on the first region, the second region being doped with p-type ions at a higher doping level than the first region.

Sintered silver joints via controlled topography of electronic packaging subcomponents

DOEpatents

Wereszczak, Andrew A.

2014-09-02

Disclosed are sintered silver bonded electronic package subcomponents and methods for making the same. Embodiments of the sintered silver bonded EPSs include topography modification of one or more metal surfaces of semiconductor devices bonded together by the sintered silver joint. The sintered silver bonded EPSs include a first semiconductor device having a first metal surface, the first metal surface having a modified topography that has been chemically etched, grit blasted, uniaxial ground and/or grid sliced connected to a second semiconductor device which may also include a first metal surface with a modified topography, a silver plating layer on the first metal surface of the first semiconductor device and a silver plating layer on the first metal surface of the second semiconductor device and a sintered silver joint between the silver plating layers of the first and second semiconductor devices which bonds the first semiconductor device to the second semiconductor device.

Method for fabricating an interconnected array of semiconductor devices

DOEpatents

Grimmer, Derrick P.; Paulson, Kenneth R.; Gilbert, James R.

1989-10-10

Semiconductor layer and conductive layer formed on a flexible substrate, divided into individual devices and interconnected with one another in series by interconnection layers and penetrating terminals.

High-resolution parallel-detection sensor array using piezo-phototronics effect

DOEpatents

Wang, Zhong L.; Pan, Caofeng

2015-07-28

A pressure sensor element includes a substrate, a first type of semiconductor material layer and an array of elongated light-emitting piezoelectric nanostructures extending upwardly from the first type of semiconductor material layer. A p-n junction is formed between each nanostructure and the first type semiconductor layer. An insulative resilient medium layer is infused around each of the elongated light-emitting piezoelectric nanostructures. A transparent planar electrode, disposed on the resilient medium layer, is electrically coupled to the top of each nanostructure. A voltage source is coupled to the first type of semiconductor material layer and the transparent planar electrode and applies a biasing voltage across each of the nanostructures. Each nanostructure emits light in an intensity that is proportional to an amount of compressive strain applied thereto.

Solid state radiative heat pump

DOEpatents

Berdahl, P.H.

1984-09-28

A solid state radiative heat pump operable at room temperature (300 K) utilizes a semiconductor having a gap energy in the range of 0.03-0.25 eV and operated reversibly to produce an excess or deficit of change carriers as compared equilibrium. In one form of the invention an infrared semiconductor photodiode is used, with forward or reverse bias, to emit an excess or deficit of infrared radiation. In another form of the invention, a homogenous semiconductor is subjected to orthogonal magnetic and electric fields to emit an excess or deficit of infrared radiation. Three methods of enhancing transmission of radiation the active surface of the semiconductor are disclosed. In one method, an anti-refection layer is coated into the active surface of the semiconductor, the anti-reflection layer having an index of refraction equal to the square root of that of the semiconductor. In the second method, a passive layer is speaced trom the active surface of the semiconductor by a submicron vacuum gap, the passive layer having an index of refractive equal to that of the semiconductor. In the third method, a coupler with a paraboloid reflecting surface surface is in contact with the active surface of the semiconductor, the coupler having an index of refraction about the same as that of the semiconductor.

Two-dimensional materials from high-throughput computational exfoliation of experimentally known compounds.

PubMed

Mounet, Nicolas; Gibertini, Marco; Schwaller, Philippe; Campi, Davide; Merkys, Andrius; Marrazzo, Antimo; Sohier, Thibault; Castelli, Ivano Eligio; Cepellotti, Andrea; Pizzi, Giovanni; Marzari, Nicola

2018-03-01

Two-dimensional (2D) materials have emerged as promising candidates for next-generation electronic and optoelectronic applications. Yet, only a few dozen 2D materials have been successfully synthesized or exfoliated. Here, we search for 2D materials that can be easily exfoliated from their parent compounds. Starting from 108,423 unique, experimentally known 3D compounds, we identify a subset of 5,619 compounds that appear layered according to robust geometric and bonding criteria. High-throughput calculations using van der Waals density functional theory, validated against experimental structural data and calculated random phase approximation binding energies, further allowed the identification of 1,825 compounds that are either easily or potentially exfoliable. In particular, the subset of 1,036 easily exfoliable cases provides novel structural prototypes and simple ternary compounds as well as a large portfolio of materials to search from for optimal properties. For a subset of 258 compounds, we explore vibrational, electronic, magnetic and topological properties, identifying 56 ferromagnetic and antiferromagnetic systems, including half-metals and half-semiconductors.

Two-dimensional materials from high-throughput computational exfoliation of experimentally known compounds

NASA Astrophysics Data System (ADS)

Mounet, Nicolas; Gibertini, Marco; Schwaller, Philippe; Campi, Davide; Merkys, Andrius; Marrazzo, Antimo; Sohier, Thibault; Castelli, Ivano Eligio; Cepellotti, Andrea; Pizzi, Giovanni; Marzari, Nicola

2018-02-01

Two-dimensional (2D) materials have emerged as promising candidates for next-generation electronic and optoelectronic applications. Yet, only a few dozen 2D materials have been successfully synthesized or exfoliated. Here, we search for 2D materials that can be easily exfoliated from their parent compounds. Starting from 108,423 unique, experimentally known 3D compounds, we identify a subset of 5,619 compounds that appear layered according to robust geometric and bonding criteria. High-throughput calculations using van der Waals density functional theory, validated against experimental structural data and calculated random phase approximation binding energies, further allowed the identification of 1,825 compounds that are either easily or potentially exfoliable. In particular, the subset of 1,036 easily exfoliable cases provides novel structural prototypes and simple ternary compounds as well as a large portfolio of materials to search from for optimal properties. For a subset of 258 compounds, we explore vibrational, electronic, magnetic and topological properties, identifying 56 ferromagnetic and antiferromagnetic systems, including half-metals and half-semiconductors.

Field-effect transistor having a superlattice channel and high carrier velocities at high applied fields

DOEpatents

Chaffin, R.J.; Dawson, L.R.; Fritz, I.J.; Osbourn, G.C.; Zipperian, T.E.

1984-04-19

In a field-effect transistor comprising a semiconductor having therein a source, a drain, a channel and a gate in operational relationship, there is provided an improvement wherein said semiconductor is a superlattice comprising alternating quantum well and barrier layers, the quantum well layers comprising a first direct gap semiconductor material which in bulk form has a certain bandgap and a curve of electron velocity versus applied electric field which has a maximum electron velocity at a certain electric field, the barrier layers comprising a second semiconductor material having a bandgap wider than that of said first semiconductor material, wherein the layer thicknesses of said quantum well and barrier layers are sufficiently thin that the alternating layers constitute a superlattice having a curve of electron velocity versus applied electric field which has a maximum electron velocity at a certain electric field, and wherein the thicknesses of said quantum well layers are selected to provide a superlattice curve of electron velocity versus applied electric field whereby, at applied electric fields higher than that at which the maximum electron velocity occurs in said first material when in bulk form, the electron velocities are higher in said superlattice than they are in said first semiconductor material in bulk form.

Precise, Self-Limited Epitaxy of Ultrathin Organic Semiconductors and Heterojunctions Tailored by van der Waals Interactions.

PubMed

Wu, Bing; Zhao, Yinghe; Nan, Haiyan; Yang, Ziyi; Zhang, Yuhan; Zhao, Huijuan; He, Daowei; Jiang, Zonglin; Liu, Xiaolong; Li, Yun; Shi, Yi; Ni, Zhenhua; Wang, Jinlan; Xu, Jian-Bin; Wang, Xinran

2016-06-08

Precise assembly of semiconductor heterojunctions is the key to realize many optoelectronic devices. By exploiting the strong and tunable van der Waals (vdW) forces between graphene and organic small molecules, we demonstrate layer-by-layer epitaxy of ultrathin organic semiconductors and heterostructures with unprecedented precision with well-defined number of layers and self-limited characteristics. We further demonstrate organic p-n heterojunctions with molecularly flat interface, which exhibit excellent rectifying behavior and photovoltaic responses. The self-limited organic molecular beam epitaxy (SLOMBE) is generically applicable for many layered small-molecule semiconductors and may lead to advanced organic optoelectronic devices beyond bulk heterojunctions.

Photovoltaic devices comprising cadmium stannate transparent conducting films and method for making

DOEpatents

Wu, Xuanzhi; Coutts, Timothy J.; Sheldon, Peter; Rose, Douglas H.

1999-01-01

A photovoltaic device having a substrate, a layer of Cd.sub.2 SnO.sub.4 disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd.sub.2 SnO.sub.4, and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd.sub.2 SnO.sub.4 layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd.sub.2 SnO.sub.4, and depositing an electrically conductive film onto the thin film of semiconductor materials.

Porous silicon carbide (SiC) semiconductor device

NASA Technical Reports Server (NTRS)

Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

1994-01-01

A semiconductor device employs at least one layer of semiconducting porous silicon carbide (SiC). The porous SiC layer has a monocrystalline structure wherein the pore sizes, shapes, and spacing are determined by the processing conditions. In one embodiment, the semiconductor device is a p-n junction diode in which a layer of n-type SiC is positioned on a p-type layer of SiC, with the p-type layer positioned on a layer of silicon dioxide. Because of the UV luminescent properties of the semiconducting porous SiC layer, it may also be utilized for other devices such as LEDs and optoelectronic devices.

Spin Interactions and Spin Dynamics in Electronic Nanostructures

DTIC Science & Technology

2006-08-31

in Semiconductor Nanostructures,” D. D. Awschalom, Plenary Speaker, 36th International Symposium on Compound Semiconductors, San Diego, CA, August 25...Electrical Manipulation of Spin Orientation in Compound Semiconductors”, M. E. Flatté, W. H. Lau, C. E. Pryor, and I. Tifrea, International Symposium...on Compound Semiconductors 2003, San Diego, August 25, 2003. 73. “Spin Dynamics in Semiconductors”, M. E. Flatté, SPINTECH II: 2nd International

Semiconductor P-I-N detector

DOEpatents

Sudharsanan, Rengarajan; Karam, Nasser H.

2001-01-01

A semiconductor P-I-N detector including an intrinsic wafer, a P-doped layer, an N-doped layer, and a boundary layer for reducing the diffusion of dopants into the intrinsic wafer. The boundary layer is positioned between one of the doped regions and the intrinsic wafer. The intrinsic wafer can be composed of CdZnTe or CdTe, the P-doped layer can be composed of ZnTe doped with copper, and the N-doped layer can be composed of CdS doped with indium. The boundary layers is formed of an undoped semiconductor material. The boundary layer can be deposited onto the underlying intrinsic wafer. The doped regions are then typically formed by a deposition process or by doping a section of the deposited boundary layer.

Photovoltaic devices comprising cadmium stannate transparent conducting films and method for making

DOEpatents

Wu, X.; Coutts, T.J.; Sheldon, P.; Rose, D.H.

1999-07-13

A photovoltaic device is disclosed having a substrate, a layer of Cd[sub 2]SnO[sub 4] disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd[sub 2]SnO[sub 4], and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd[sub 2]SnO[sub 4] layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd[sub 2]SnO[sub 4], and depositing an electrically conductive film onto the thin film of semiconductor materials. 10 figs.

Dry texturing of solar cells

DOEpatents

Sopori, B.L.

1994-10-25

A textured backside of a semiconductor device for increasing light scattering and absorption in a semiconductor substrate is accomplished by applying infrared radiation to the front side of a semiconductor substrate that has a metal layer deposited on its backside in a time-energy profile that first produces pits in the backside surface and then produces a thin, highly reflective, low resistivity, epitaxial alloy layer over the entire area of the interface between the semiconductor substrate and a metal contact layer. The time-energy profile includes ramping up to a first energy level and holding for a period of time to create the desired pit size and density and then rapidly increasing the energy to a second level in which the entire interface area is melted and alloyed quickly. After holding the second energy level for a sufficient time to develop the thin alloy layer over the entire interface area, the energy is ramped down to allow epitaxial crystal growth in the alloy layer. The result is a textured backside on an optically reflective, low resistivity alloy interface between the semiconductor substrate and the metal electrical contact layer. 9 figs.

Dry texturing of solar cells

DOEpatents

Sopori, Bhushan L.

1994-01-01

A textured backside of a semiconductor device for increasing light scattering and absorption in a semiconductor substrate is accomplished by applying infrared radiation to the front side of a semiconductor substrate that has a metal layer deposited on its backside in a time-energy profile that first produces pits in the backside surface and then produces a thin, highly reflective, low resistivity, epitaxial alloy layer over the entire area of the interface between the semiconductor substrate and a metal contact layer. The time-energy profile includes ramping up to a first energy level and holding for a period of time to create the desired pit size and density and then rapidly increasing the energy to a second level in which the entire interface area is melted and alloyed quickly. After holding the second energy level for a sufficient time to develop the thin alloy layer over the entire interface area, the energy is ramped down to allow epitaxial crystal growth in the alloy layer. The result is a textured backside an optically reflective, low resistivity alloy interface between the semiconductor substrate and the metal electrical contact layer.

Nanomembrane structures having mixed crystalline orientations and compositions

DOEpatents

Lagally, Max G.; Scott, Shelley A.; Savage, Donald E.

2014-08-12

The present nanomembrane structures include a multilayer film comprising a single-crystalline layer of semiconductor material disposed between two other single-crystalline layers of semiconductor material. A plurality of holes extending through the nanomembrane are at least partially, and preferably entirely, filled with a filler material which is also a semiconductor, but which differs from the nanomembrane semiconductor materials in composition, crystal orientation, or both.

CATALYTIC PROPERTIES OF SEMICONDUCTORS.

DTIC Science & Technology

SEMICONDUCTORS, CATALYSTS), (*CATALYSIS, REACTION KINETICS), (* SODIUM COMPOUNDS, TUNGSTATES), (*GALLIUM ALLOYS, ARSENIC ALLOYS), (*YTTERBIUM...COMPOUNDS, SILICIDES ), (*GERMANIUM, CATALYSIS), INTERNAL CONVERSION, EXCHANGE REACTIONS, HEAT OF ACTIVATION, THERMODYNAMICS, DEUTERIUM, POWDERS, SURFACES, HYDROGEN

Die singulation method

DOEpatents

Swiler, Thomas P.; Garcia, Ernest J.; Francis, Kathryn M.

2013-06-11

A method is disclosed for singulating die from a semiconductor substrate (e.g. a semiconductor-on-insulator substrate or a bulk silicon substrate) containing an oxide layer (e.g. silicon dioxide or a silicate glass) and one or more semiconductor layers (e.g. monocrystalline or polycrystalline silicon) located above the oxide layer. The method etches trenches through the substrate and through each semiconductor layer about the die being singulated, with the trenches being offset from each other around at least a part of the die so that the oxide layer between the trenches holds the substrate and die together. The trenches can be anisotropically etched using a Deep Reactive Ion Etching (DRIE) process. After the trenches are etched, the oxide layer between the trenches can be etched away with an HF etchant to singulate the die. A release fixture can be located near one side of the substrate to receive the singulated die.

Die singulation method

DOEpatents

Swiler, Thomas P [Albuquerque, NM; Garcia, Ernest J [Albuquerque, NM; Francis, Kathryn M [Rio Rancho, NM

2014-01-07

A method is disclosed for singulating die from a semiconductor substrate (e.g. a semiconductor-on-insulator substrate or a bulk silicon substrate) containing an oxide layer (e.g. silicon dioxide or a silicate glass) and one or more semiconductor layers (e.g. monocrystalline or polycrystalline silicon) located above the oxide layer. The method etches trenches through the substrate and through each semiconductor layer about the die being singulated, with the trenches being offset from each other around at least a part of the die so that the oxide layer between the trenches holds the substrate and die together. The trenches can be anisotropically etched using a Deep Reactive Ion Etching (DRIE) process. After the trenches are etched, the oxide layer between the trenches can be etched away with a HF etchant to singulate the die. A release fixture can be located near one side of the substrate to receive the singulated die.

Method for depositing layers of high quality semiconductor material

DOEpatents

Guha, Subhendu; Yang, Chi C.

2001-08-14

Plasma deposition of substantially amorphous semiconductor materials is carried out under a set of deposition parameters which are selected so that the process operates near the amorphous/microcrystalline threshold. This threshold varies as a function of the thickness of the depositing semiconductor layer; and, deposition parameters, such as diluent gas concentrations, must be adjusted as a function of layer thickness. Also, this threshold varies as a function of the composition of the depositing layer, and in those instances where the layer composition is profiled throughout its thickness, deposition parameters must be adjusted accordingly so as to maintain the amorphous/microcrystalline threshold.

Free Surface Properties of III-V Compound Semiconductor Surfaces.

DTIC Science & Technology

1980-06-01

selvage. Most important is the fact that atomic displacements also occur up to two layers into the substrate in the IaSb (ll0) selvage, presumably because of...result is that the interaction is of a disordering nature. 1 2,1 3 We took LEED measurements for a very large range of exposure to molecular oxygen (103...which the Al replaces the Ga. Arguments in favor of this reaction are given by measured photoemission peak shifts: 1 8󈧗 the Ga 3-d core level shifts

Novel Engineered Compound Semiconductor Heterostructures for Advanced Electronics Applications

DTIC Science & Technology

1992-06-22

and using an optimal 100 A set-back layer. This is an indication that carbon exhibits a low diffusivity in Ino.53GaO.47As films , too. Several issues...number of hydrocar- CC14 flow of 100 sccm. The p-type carrier concentration is bon sources has either not been successful, or has led to films highest...in InP by measuring the acceptor luminescence in undoped InP grown by LPE , PH3-VPE and LEC techniques and in intentionally doped material prepared by

Temperature-dependent magnetic anisotropy in the layered magnetic semiconductors Cr I3 and CrB r3

NASA Astrophysics Data System (ADS)

Richter, Nils; Weber, Daniel; Martin, Franziska; Singh, Nirpendra; Schwingenschlögl, Udo; Lotsch, Bettina V.; Kläui, Mathias

2018-02-01

Chromium trihalides are layered and exfoliable semiconductors and exhibit unusual magnetic properties with a surprising temperature dependence of the magnetization. By analyzing the evolution of the magnetocrystalline anisotropy with temperature in chromium iodide Cr I3 , we find it strongly changes from Ku=300 ±50 kJ / m3 at 5 K to Ku=43 ±7 kJ / m3 at 60 K , close to the Curie temperature. We draw a direct comparison to CrB r3 , which serves as a reference, and where we find results consistent with literature. In particular, we show that the anisotropy change in the iodide compound is more than 3 times larger than in the bromide. We analyze this temperature dependence using a classical model, showing that the anisotropy constant scales with the magnetization at any given temperature below the Curie temperature, indicating that the temperature dependence can be explained by a dominant uniaxial anisotropy where this scaling results from local spin clusters having thermally induced magnetization directions that deviate from the overall magnetization.

Lattice-mismatched GaInP LED devices and methods of fabricating same

DOEpatents

Mascarenhas, Angelo; Steiner, Myles A; Bhusal, Lekhnath; Zhang, Yong

2014-10-21

A method (100) of fabricating an LED or the active regions of an LED and an LED (200). The method includes growing, depositing or otherwise providing a bottom cladding layer (208) of a selected semiconductor alloy with an adjusted bandgap provided by intentionally disordering the structure of the cladding layer (208). A first active layer (202) may be grown above the bottom cladding layer (208) wherein the first active layer (202) is fabricated of the same semiconductor alloy, with however, a partially ordered structure. The first active layer (202) will also be fabricated to include a selected n or p type doping. The method further includes growing a second active layer (204) above the first active layer (202) where the second active layer (204) Is fabricated from the same semiconductor alloy.

Amorphous semiconductor solar cell

DOEpatents

Dalal, Vikram L.

1981-01-01

A solar cell comprising a back electrical contact, amorphous silicon semiconductor base and junction layers and a top electrical contact includes in its manufacture the step of heat treating the physical junction between the base layer and junction layer to diffuse the dopant species at the physical junction into the base layer.

Graphene-based hybrid structures combined with functional materials of ferroelectrics and semiconductors.

PubMed

Jie, Wenjing; Hao, Jianhua

2014-06-21

Fundamental studies and applications of 2-dimensional (2D) graphene may be deepened and broadened via combining graphene sheets with various functional materials, which have been extended from the traditional insulator of SiO2 to a versatile range of dielectrics, semiconductors and metals, as well as organic compounds. Among them, ferroelectric materials have received much attention due to their unique ferroelectric polarization. As a result, many attractive characteristics can be shown in graphene/ferroelectric hybrid systems. On the other hand, graphene can be integrated with conventional semiconductors and some newly-discovered 2D layered materials to form distinct Schottky junctions, yielding fascinating behaviours and exhibiting the potential for various applications in future functional devices. This review article is an attempt to illustrate the most recent progress in the fabrication, operation principle, characterization, and promising applications of graphene-based hybrid structures combined with various functional materials, ranging from ferroelectrics to semiconductors. We focus on mechanically exfoliated and chemical-vapor-deposited graphene sheets integrated in numerous advanced devices. Some typical hybrid structures have been highlighted, aiming at potential applications in non-volatile memories, transparent flexible electrodes, solar cells, photodetectors, and so on.

Graphene-based hybrid structures combined with functional materials of ferroelectrics and semiconductors

NASA Astrophysics Data System (ADS)

Jie, Wenjing; Hao, Jianhua

2014-05-01

Fundamental studies and applications of 2-dimensional (2D) graphene may be deepened and broadened via combining graphene sheets with various functional materials, which have been extended from the traditional insulator of SiO2 to a versatile range of dielectrics, semiconductors and metals, as well as organic compounds. Among them, ferroelectric materials have received much attention due to their unique ferroelectric polarization. As a result, many attractive characteristics can be shown in graphene/ferroelectric hybrid systems. On the other hand, graphene can be integrated with conventional semiconductors and some newly-discovered 2D layered materials to form distinct Schottky junctions, yielding fascinating behaviours and exhibiting the potential for various applications in future functional devices. This review article is an attempt to illustrate the most recent progress in the fabrication, operation principle, characterization, and promising applications of graphene-based hybrid structures combined with various functional materials, ranging from ferroelectrics to semiconductors. We focus on mechanically exfoliated and chemical-vapor-deposited graphene sheets integrated in numerous advanced devices. Some typical hybrid structures have been highlighted, aiming at potential applications in non-volatile memories, transparent flexible electrodes, solar cells, photodetectors, and so on.

Crystal growth of device quality GaAs in space

NASA Technical Reports Server (NTRS)

Gatos, H. C.; Lagowski, J.

1986-01-01

It was established that the findings on elemental semiconductors Ge and Si regarding crystal growth, segregation, chemical composition, defect interactions, and materials properties-electronic properties relationships are not necessarily applicable to GaAs (and to other semiconductor compounds). In many instances totally unexpected relationships were found to prevail. It was further established that in compound semiconductors with a volatile constituent, control of stoichiometry is far more critical than any other crystal growth parameter. It was also shown that, due to suppression of nonstoichiometric fluctuations, the advantages of space for growth of semiconductor compounds extend far beyond those observed in elemental semiconductors. A novel configuration was discovered for partial confinement of GaAs melt in space which overcomes the two major problems associated with growth of semiconductors in total confinement. They are volume expansion during solidification and control of pressure of the volatile constituent. These problems are discussed in detail.

Monolayer-Mediated Growth of Organic Semiconductor Films with Improved Device Performance.

PubMed

Huang, Lizhen; Hu, Xiaorong; Chi, Lifeng

2015-09-15

Increased interest in wearable and smart electronics is driving numerous research works on organic electronics. The control of film growth and patterning is of great importance when targeting high-performance organic semiconductor devices. In this Feature Article, we summarize our recent work focusing on the growth, crystallization, and device operation of organic semiconductors intermediated by ultrathin organic films (in most cases, only a monolayer). The site-selective growth, modified crystallization and morphology, and improved device performance of organic semiconductor films are demonstrated with the help of the inducing layers, including patterned and uniform Langmuir-Blodgett monolayers, crystalline ultrathin organic films, and self-assembled polymer brush films. The introduction of the inducing layers could dramatically change the diffusion of the organic semiconductors on the surface and the interactions between the active layer with the inducing layer, leading to improved aggregation/crystallization behavior and device performance.

(Ag{sub 2}TeS{sub 3}){sub 2} {small_bullet} A{sub 2}S{sub 6} (A = Rb, Cs) : layers of silver thiotellurite intergrown with alkali-metal polysulfides.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, S. L.; Jang, J. I.; Ketterson, J. B.

2010-09-22

The layered compounds RbAg{sub 2}TeS{sub 6} and CsAg{sub 2}TeS{sub 6} crystallize in the noncentrosymmetric space group P6{sub 3}cm, with a = 19.15 {angstrom}, c = 14.64 {angstrom}, and V = 4648 {angstrom}{sup 3} and a = 19.41 {angstrom}, c = 14.84 {angstrom}, and V = 4839 {angstrom}{sup 3}, respectively. The structures are composed of neutral [Ag{sub 2}TeS{sub 3}] layers alternating with charge-balanced salt layers containing polysulfide chains of [S{sub 6}]{sup 2-} and alkali-metal ions. RbAg{sub 2}TeS{sub 6} and CsAg{sub 2}TeS{sub 6} are air- and water-stable, wide-band-gap semiconductors (E{sub g} {approx} 2.0 eV) exhibiting nonlinear-optical second-harmonic generation.

Metallization for Yb14MnSb11-Based Thermoelectric Materials

NASA Technical Reports Server (NTRS)

Firdosy, Samad; Li, Billy Chun-Yip; Ravi, Vilupanur; Sakamoto, Jeffrey; Caillat, Thierry; Ewell, Richard C.; Brandon, Erik J.

2011-01-01

Thermoelectric materials provide a means for converting heat into electrical power using a fully solid-state device. Power-generating devices (which include individual couples as well as multicouple modules) require the use of ntype and p-type thermoelectric materials, typically comprising highly doped narrow band-gap semiconductors which are connected to a heat collector and electrodes. To achieve greater device efficiency and greater specific power will require using new thermoelectric materials, in more complex combinations. One such material is the p-type compound semiconductor Yb14MnSb11 (YMS), which has been demonstrated to have one of the highest ZT values at 1,000 C, the desired operational temperature of many space-based radioisotope thermoelectric generators (RTGs). Despite the favorable attributes of the bulk YMS material, it must ultimately be incorporated into a power-generating device using a suitable joining technology. Typically, processes such as diffusion bonding and/or brazing are used to join thermoelectric materials to the heat collector and electrodes, with the goal of providing a stable, ohmic contact with high thermal conductivity at the required operating temperature. Since YMS is an inorganic compound featuring chemical bonds with a mixture of covalent and ionic character, simple metallurgical diffusion bonding is difficult to implement. Furthermore, the Sb within YMS readily reacts with most metals to form antimonide compounds with a wide range of stoichiometries. Although choosing metals that react to form high-melting-point antimonides could be employed to form a stable reaction bond, it is difficult to limit the reactivity of Sb in YMS such that the electrode is not completely consumed at an operating temperature of 1,000 C. Previous attempts to form suitable metallization layers resulted in poor bonding, complete consumption of the metallization layer or fracture within the YMS thermoelement (or leg).

Solid state radiative heat pump

DOEpatents

Berdahl, Paul H.

1986-01-01

A solid state radiative heat pump (10, 50, 70) operable at room temperature (300.degree. K.) utilizes a semiconductor having a gap energy in the range of 0.03-0.25 eV and operated reversibly to produce an excess or deficit of charge carriers as compared to thermal equilibrium. In one form of the invention (10, 70) an infrared semiconductor photodiode (21, 71) is used, with forward or reverse bias, to emit an excess or deficit of infrared radiation. In another form of the invention (50), a homogeneous semiconductor (51) is subjected to orthogonal magnetic and electric fields to emit an excess or deficit of infrared radiation. Three methods of enhancing transmission of radiation through the active surface of the semiconductor are disclosed. In one method, an anti-reflection layer (19) is coated into the active surface (13) of the semiconductor (11), the anti-reflection layer (19) having an index of refraction equal to the square root of that of the semiconductor (11). In the second method, a passive layer (75) is spaced from the active surface (73) of the semiconductor (71) by a submicron vacuum gap, the passive layer having an index of refractive equal to that of the semiconductor. In the third method, a coupler (91) with a paraboloid reflecting surface (92) is in contact with the active surface (13, 53) of the semiconductor (11, 51), the coupler having an index of refraction about the same as that of the semiconductor.

Optical devices featuring nonpolar textured semiconductor layers

DOEpatents

Moustakas, Theodore D; Moldawer, Adam; Bhattacharyya, Anirban; Abell, Joshua

2013-11-26

A semiconductor emitter, or precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate in a nonpolar orientation. The textured layers enhance light extraction, and the use of nonpolar orientation greatly enhances internal quantum efficiency compared to conventional devices. Both the internal and external quantum efficiencies of emitters of the invention can be 70-80% or higher. The invention provides highly efficient light emitting diodes suitable for solid state lighting.

SCB initiator

DOEpatents

Bickes Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

1994-11-01

A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

SCB initiator

DOEpatents

Bickes, Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

1994-01-01

A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

Novel organic semiconductors and dielectric materials for high performance and low-voltage organic thin-film transistors

NASA Astrophysics Data System (ADS)

Yoon, Myung-Han

Two novel classes of organic semiconductors based on perfluoroarene/arene-modified oligothiophenes and perfluoroacyl/acyl-derivatized quaterthiophens are developed. The frontier molecular orbital energies of these compounds are studied by optical spectroscopy and electrochemistry while solid-state/film properties are investigated by thermal analysis, x-ray diffraction, and scanning electron microscopy. Organic thin film transistors (OTFTs) performance parameters are discussed in terms of the interplay between semiconductor molecular energetics and film morphologies/microstructures. For perfluoroarene-thiophene oligomer systems, majority charge carrier type and mobility exhibit a strong correlation with the regiochemistry of perfluoroarene incorporation. In quaterthiophene-based semiconductors, carbonyl-functionalization allows tuning of the majority carrier type from p-type to ambipolar and to n-type. In situ conversion of a p-type semiconducting film to n-type film is also demonstrated. Very thin self-assembled or spin-on organic dielectric films have been integrated into OTFTs to achieve 1 - 2 V operating voltages. These new dielectrics are deposited either by layer-by-layer solution phase deposition of molecular precursors or by spin-coating a mixture of polymer and crosslinker, resulting in smooth and virtually pinhole-free thin films having exceptionally large capacitances (300--700 nF/cm2) and low leakage currents (10 -9 - 10-7 A/cm2). These organic dielectrics are compatible with various vapor- or solution-deposited p- and n-channel organic semiconductors. Furthermore, it is demonstrated that spin-on crosslinked-polymer-blend dielectrics can be employed for large-area/patterned electronics, and complementary inverters. A general approach for probing semiconductor-dielectric interface effects on OTFT performance parameters using bilayer gate dielectrics is presented. Organic semiconductors having p-, n-type, or ambipolar majority charge carriers are grown on six different bilayer dielectrics consisting of various spin-coated polymers/HMDS on 300 nm SiO2/p+-Si, followed by transistor fabrication. In case of air-sensitive n-type semiconductors, dielectric surface modifications induce large variations in the corresponding OTFT performance parameters while film morphologies and microstructures remain unchanged. In contrast, the device performance of air-stable n-type and p-type semiconductors is not significantly affected by dielectric surface modifications. The origin of the mobility sensitivity to the various surface chemistries in the case of air sensitive n-type semiconductors is found to be due to electron trapping by silanol and carbonyl functionalities at the semiconductor-dielectric interface.

Electron gas grid semiconductor radiation detectors

DOEpatents

Lee, Edwin Y.; James, Ralph B.

2002-01-01

An electron gas grid semiconductor radiation detector (EGGSRAD) useful for gamma-ray and x-ray spectrometers and imaging systems is described. The radiation detector employs doping of the semiconductor and variation of the semiconductor detector material to form a two-dimensional electron gas, and to allow transistor action within the detector. This radiation detector provides superior energy resolution and radiation detection sensitivity over the conventional semiconductor radiation detector and the "electron-only" semiconductor radiation detectors which utilize a grid electrode near the anode. In a first embodiment, the EGGSRAD incorporates delta-doped layers adjacent the anode which produce an internal free electron grid well to which an external grid electrode can be attached. In a second embodiment, a quantum well is formed between two of the delta-doped layers, and the quantum well forms the internal free electron gas grid to which an external grid electrode can be attached. Two other embodiments which are similar to the first and second embodiment involve a graded bandgap formed by changing the composition of the semiconductor material near the first and last of the delta-doped layers to increase or decrease the conduction band energy adjacent to the delta-doped layers.

Method of transferring strained semiconductor structure

DOEpatents

Nastasi, Michael A [Santa Fe, NM; Shao, Lin [College Station, TX

2009-12-29

The transfer of strained semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate to the other substrate. The multilayer structure includes at least one strained semiconductor layer and at least one strain-induced seed layer. The strain-induced seed layer can be optionally etched away after the layer transfer.

InP solar cell with window layer

NASA Technical Reports Server (NTRS)

Jain, Raj K. (Inventor); Landis, Geoffrey A. (Inventor)

1994-01-01

The invention features a thin light transmissive layer of the ternary semiconductor indium aluminum arsenide (InAlAs) as a front surface passivation or 'window' layer for p-on-n InP solar cells. The window layers of the invention effectively reduce front surface recombination of the object semiconductors thereby increasing the efficiency of the cells.

Fabrication of optically reflecting ohmic contacts for semiconductor devices

DOEpatents

Sopori, Bhushan L.

1995-01-01

A method is provided to produce a low-resistivity ohmic contact having high optical reflectivity on one side of a semiconductor device. The contact is formed by coating the semiconductor substrate with a thin metal film on the back reflecting side and then optically processing the wafer by illuminating it with electromagnetic radiation of a predetermined wavelength and energy level through the front side of the wafer for a predetermined period of time. This method produces a thin epitaxial alloy layer between the semiconductor substrate and the metal layer when a crystalline substrate is used. The alloy layer provides both a low-resistivity ohmic contact and high optical reflectance.

Solid state photosensitive devices which employ isolated photosynthetic complexes

DOEpatents

Peumans, Peter; Forrest, Stephen R.

2009-09-22

Solid state photosensitive devices including photovoltaic devices are provided which comprise a first electrode and a second electrode in superposed relation; and at least one isolated Light Harvesting Complex (LHC) between the electrodes. Preferred photosensitive devices comprise an electron transport layer formed of a first photoconductive organic semiconductor material, adjacent to the LHC, disposed between the first electrode and the LHC; and a hole transport layer formed of a second photoconductive organic semiconductor material, adjacent to the LHC, disposed between the second electrode and the LHC. Solid state photosensitive devices of the present invention may comprise at least one additional layer of photoconductive organic semiconductor material disposed between the first electrode and the electron transport layer; and at least one additional layer of photoconductive organic semiconductor material, disposed between the second electrode and the hole transport layer. Methods of generating photocurrent are provided which comprise exposing a photovoltaic device of the present invention to light. Electronic devices are provided which comprise a solid state photosensitive device of the present invention.

p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

DOEpatents

Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

2014-11-25

The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

Synthesis of Freestanding Single-crystal Perovskite Films and Heterostructures by Etching of Sacrificial Water-soluble Layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Di; Baek, David J.; Hong, Seung Sae

2016-08-22

The ability to create and manipulate materials in two-dimensional (2D) form has repeatedly had transformative impact on science and technology. In parallel with the exfoliation and stacking of intrinsically layered crystals, atomic-scale thin film growth of complex materials has enabled the creation of artificial 2D heterostructures with novel functionality and emergent phenomena, as seen in perovskite heterostructures. However, separation of these layers from the growth substrate has proven challenging, limiting the manipulation capabilities of these heterostructures with respect to exfoliated materials. Here we present a general method to create freestanding perovskite membranes. The key is the epitaxial growth of water-solublemore » Sr 3Al 2O 6 on perovskite substrates, followed by in situ growth of films and heterostructures. Millimetre-size single-crystalline membranes are produced by etching the Sr 3Al 2O 6 layer in water, providing the opportunity to transfer them to arbitrary substrates and integrate them with heterostructures of semiconductors and layered compounds.« less

Processes for multi-layer devices utilizing layer transfer

DOEpatents

Nielson, Gregory N; Sanchez, Carlos Anthony; Tauke-Pedretti, Anna; Kim, Bongsang; Cederberg, Jeffrey; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

2015-02-03

A method includes forming a release layer over a donor substrate. A plurality of devices made of a first semiconductor material are formed over the release layer. A first dielectric layer is formed over the plurality of devices such that all exposed surfaces of the plurality of devices are covered by the first dielectric layer. The plurality of devices are chemically attached to a receiving device made of a second semiconductor material different than the first semiconductor material, the receiving device having a receiving substrate attached to a surface of the receiving device opposite the plurality of devices. The release layer is etched to release the donor substrate from the plurality of devices. A second dielectric layer is applied over the plurality of devices and the receiving device to mechanically attach the plurality of devices to the receiving device.

Pronounced Photovoltaic Response from Multilayered Transition-Metal Dichalcogenides PN-Junctions.

PubMed

Memaran, Shahriar; Pradhan, Nihar R; Lu, Zhengguang; Rhodes, Daniel; Ludwig, Jonathan; Zhou, Qiong; Ogunsolu, Omotola; Ajayan, Pulickel M; Smirnov, Dmitry; Fernández-Domínguez, Antonio I; García-Vidal, Francisco J; Balicas, Luis

2015-11-11

Transition metal dichalcogenides (TMDs) are layered semiconductors with indirect band gaps comparable to Si. These compounds can be grown in large area, while their gap(s) can be tuned by changing their chemical composition or by applying a gate voltage. The experimental evidence collected so far points toward a strong interaction with light, which contrasts with the small photovoltaic efficiencies η ≤ 1% extracted from bulk crystals or exfoliated monolayers. Here, we evaluate the potential of these compounds by studying the photovoltaic response of electrostatically generated PN-junctions composed of approximately 10 atomic layers of MoSe2 stacked onto the dielectric h-BN. In addition to ideal diode-like response, we find that these junctions can yield, under AM-1.5 illumination, photovoltaic efficiencies η exceeding 14%, with fill factors of ~70%. Given the available strategies for increasing η such as gap tuning, improving the quality of the electrical contacts, or the fabrication of tandem cells, our study suggests a remarkable potential for photovoltaic applications based on TMDs.

Chemoresistive gas sensor

DOEpatents

Hirschfeld, T.B.

1985-09-30

A chemoresistive gas sensor is provided which has improved sensitivity. A layer of organic semiconductor is disposed between two electrodes which, in turn, are connected to a voltage source. High conductivity material is dispersed within the layer of organic semiconductor in the form of very small particles, or islands. The average interisland spacing is selected so that the predominant mode of current flow is by way of electron tunneling. Adsorption of gaseous contaminant onto the layer of organic semiconductor modulates the tunneling current in a quantitative manner.

Chemoresistive gas sensor

DOEpatents

Hirschfeld, Tomas B.

1987-01-01

A chemoresistive gas sensor is provided which has improved sensitivity. A layer of organic semiconductor is disposed between two electrodes which, in turn, are connected to a voltage source. High conductivity material is dispersed within the layer of organic semiconductor in the form of very small particles, or islands. The average interisland spacing is selected so that the predominant mode of current flow is by way of electron funneling. Adsorption of gaseous contaminant onto the layer of organic semiconductor modulates the tunneling current in a quantitative manner.

Chemoresistive gas sensor

DOEpatents

Hirschfeld, T.B.

1987-06-23

A chemoresistive gas sensor is provided which has improved sensitivity. A layer of organic semiconductor is disposed between two electrodes which, in turn, are connected to a voltage source. High conductivity material is dispersed within the layer of organic semiconductor in the form of very small particles, or islands. The average interisland spacing is selected so that the predominant mode of current flow is by way of electron funneling. Adsorption of gaseous contaminant onto the layer of organic semiconductor modulates the tunneling current in a quantitative manner. 2 figs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usanov, D. A., E-mail: UsanovDA@info.sgu.ru; Nikitov, S. A.; Skripal, A. V.

A method is proposed for the measurement of the electrophysical characteristics of semiconductor structures: the electrical conductivity of the n layer, which plays the role of substrate for a semiconductor structure, and the thickness and electrical conductivity of the strongly doped epitaxial n{sup +} layer. The method is based on the use of a one-dimensional microwave photonic crystal with a violation of periodicity containing the semiconductor structure under investigation. The characteristics of epitaxial gallium-arsenide structures consisting of an epitaxial layer and the semi-insulating substrate measured by this method are presented.

Selective epitaxy using the gild process

DOEpatents

Weiner, Kurt H.

1992-01-01

The present invention comprises a method of selective epitaxy on a semiconductor substrate. The present invention provides a method of selectively forming high quality, thin GeSi layers in a silicon circuit, and a method for fabricating smaller semiconductor chips with a greater yield (more error free chips) at a lower cost. The method comprises forming an upper layer over a substrate, and depositing a reflectivity mask which is then removed over selected sections. Using a laser to melt the unmasked sections of the upper layer, the semiconductor material in the upper layer is heated and diffused into the substrate semiconductor material. By varying the amount of laser radiation, the epitaxial layer is formed to a controlled depth which may be very thin. When cooled, a single crystal epitaxial layer is formed over the patterned substrate. The present invention provides the ability to selectively grow layers of mixed semiconductors over patterned substrates such as a layer of Ge.sub.x Si.sub.1-x grown over silicon. Such a process may be used to manufacture small transistors that have a narrow base, heavy doping, and high gain. The narrowness allows a faster transistor, and the heavy doping reduces the resistance of the narrow layer. The process does not require high temperature annealing; therefore materials such as aluminum can be used. Furthermore, the process may be used to fabricate diodes that have a high reverse breakdown voltage and a low reverse leakage current.

Semiconductor devices incorporating multilayer interference regions

DOEpatents

Biefeld, Robert M.; Drummond, Timothy J.; Gourley, Paul L.; Zipperian, Thomas E.

1990-01-01

A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration.

Coincident site lattice-matched growth of semiconductors on substrates using compliant buffer layers

DOEpatents

Norman, Andrew

2016-08-23

A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a silicon substrate using a compliant buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The compliant buffer material and semiconductor materials may be deposited using coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The coincident site lattice matching epitaxial process, as well as the use of a ductile buffer material, reduce the internal stresses and associated crystal defects within the deposited semiconductor materials fabricated using the disclosed method. As a result, the semiconductor devices provided herein possess enhanced performance characteristics due to a relatively low density of crystal defects.

Ionic electrodeposition of II-VI and III-V compounds. III. Computer simulation of quasi-rest potentials for M/sub 1/X/sub 1/ compounds analogous to CdTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engelken, R.D.

1987-04-01

The quasi-rest potential (QRP) has been proposed as a key quantity in characterizing compound semiconductor (e.g. CdTe) electrodeposition. This article expands the modeling/simulation representative of Cd/sub x/Te in chemical equilibrium to calculate two ''QRP's'': E/sub M/1/sub /, the mixed potential occurring immediately after current interruption and before any relaxation in double layer ion concentration and significant ion exchange/surface stoichiometry change occur, and E/sub M/2/sub /, another mixed potential occurring after the double layer ion concentrations have relaxed to their bulk values but still before any significant surface composition change occurs. Significant predictions include existence of a dramatic negative transition inmore » QRP, with negative-going deposition potential, centered on the potential of perfect stoichiometry (PPS), inequality, in general, between the PPS and E/sub M/1/sub / unless the deposit remains in equilibrium with the electrolyte (no ion exchange at open circuit), negligible sensitivity of QRP-E curves to the activity coefficient parameter implying the importance of the PPS in characterizing compound deposition, and disappearance of the transition structure for sufficiently positive Gibbs free energies.« less

Fabrication of optically reflecting ohmic contacts for semiconductor devices

DOEpatents

Sopori, B.L.

1995-07-04

A method is provided to produce a low-resistivity ohmic contact having high optical reflectivity on one side of a semiconductor device. The contact is formed by coating the semiconductor substrate with a thin metal film on the back reflecting side and then optically processing the wafer by illuminating it with electromagnetic radiation of a predetermined wavelength and energy level through the front side of the wafer for a predetermined period of time. This method produces a thin epitaxial alloy layer between the semiconductor substrate and the metal layer when a crystalline substrate is used. The alloy layer provides both a low-resistivity ohmic contact and high optical reflectance. 5 figs.

Semiconductor devices incorporating multilayer interference regions

DOEpatents

Biefeld, R.M.; Drummond, T.J.; Gourley, P.L.; Zipperian, T.E.

1987-08-31

A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration. 8 figs.

Context-based automated defect classification system using multiple morphological masks

DOEpatents

Gleason, Shaun S.; Hunt, Martin A.; Sari-Sarraf, Hamed

2002-01-01

Automatic detection of defects during the fabrication of semiconductor wafers is largely automated, but the classification of those defects is still performed manually by technicians. This invention includes novel digital image analysis techniques that generate unique feature vector descriptions of semiconductor defects as well as classifiers that use these descriptions to automatically categorize the defects into one of a set of pre-defined classes. Feature extraction techniques based on multiple-focus images, multiple-defect mask images, and segmented semiconductor wafer images are used to create unique feature-based descriptions of the semiconductor defects. These feature-based defect descriptions are subsequently classified by a defect classifier into categories that depend on defect characteristics and defect contextual information, that is, the semiconductor process layer(s) with which the defect comes in contact. At the heart of the system is a knowledge database that stores and distributes historical semiconductor wafer and defect data to guide the feature extraction and classification processes. In summary, this invention takes as its input a set of images containing semiconductor defect information, and generates as its output a classification for the defect that describes not only the defect itself, but also the location of that defect with respect to the semiconductor process layers.

Antiferromagnetism in the van der Waals layered spin-lozenge semiconductor CrTe 3

DOE PAGES

McGuire, Michael A.; Garlea, V. Ovidiu; KC, Santosh; ...

2017-04-14

We have investigated the crystallographic, magnetic, and transport properties of the van der Waals bonded, layered compound CrTe 3 on single-crystal and polycrystalline materials. Furthermore, the crystal structure contains layers made up of lozenge-shaped Cr 4 tetramers. Electrical resistivity measurements show the crystals to be semiconducting, with a temperature dependence consistent with a band gap of 0.3 eV. The magnetic susceptibility exhibits a broad maximum near 300 K characteristic of low dimensional magnetic systems. Weak anomalies are observed in the susceptibility and heat capacity near 55 K, and single-crystal neutron diffraction reveals the onset of long-range antiferromagnetic order at thismore » temperature. Strongly dispersive spin waves are observed in the ordered state. Significant magnetoelastic coupling is indicated by the anomalous temperature dependence of the lattice parameters and is evident in structural optimization in van der Waals density functional theory calculations for different magnetic configurations. The cleavability of the compound is apparent from its handling and is confirmed by first-principles calculations, which predict a cleavage energy 0.5 J / m 2 , similar to graphite. Based on our results, CrTe 3 is identified as a promising compound for studies of low dimensional magnetism in bulk crystals as well as magnetic order in monolayer materials and van der Waals heterostructures.« less

Antiferromagnetism in the van der Waals layered spin-lozenge semiconductor CrTe 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGuire, Michael A.; Garlea, V. Ovidiu; KC, Santosh

We have investigated the crystallographic, magnetic, and transport properties of the van der Waals bonded, layered compound CrTe 3 on single-crystal and polycrystalline materials. Furthermore, the crystal structure contains layers made up of lozenge-shaped Cr 4 tetramers. Electrical resistivity measurements show the crystals to be semiconducting, with a temperature dependence consistent with a band gap of 0.3 eV. The magnetic susceptibility exhibits a broad maximum near 300 K characteristic of low dimensional magnetic systems. Weak anomalies are observed in the susceptibility and heat capacity near 55 K, and single-crystal neutron diffraction reveals the onset of long-range antiferromagnetic order at thismore » temperature. Strongly dispersive spin waves are observed in the ordered state. Significant magnetoelastic coupling is indicated by the anomalous temperature dependence of the lattice parameters and is evident in structural optimization in van der Waals density functional theory calculations for different magnetic configurations. The cleavability of the compound is apparent from its handling and is confirmed by first-principles calculations, which predict a cleavage energy 0.5 J / m 2 , similar to graphite. Based on our results, CrTe 3 is identified as a promising compound for studies of low dimensional magnetism in bulk crystals as well as magnetic order in monolayer materials and van der Waals heterostructures.« less

Alternative photocatalysts to TiO2 for the photocatalytic reduction of CO2

NASA Astrophysics Data System (ADS)

Nikokavoura, Aspasia; Trapalis, Christos

2017-01-01

The increased concentration of CO2 in the atmosphere, originating from the burning of fossil fuels in stationary and mobile sources, is referred as the "Anthropogenic Greenhouse Effect" and constitutes a major environmental concern. The scientific community is highly concerned about the resulting enhancement of the mean atmospheric temperature, so a vast diversity of methods has been applied. Thermochemical, electrochemical, photocatalytic, photoelectrochemical processes, as well as combination of solar electricity generation and water splitting processes have been performed in order to lower the CO2 atmospheric levels. Photocatalytic methods are environmental friendly and succeed in reducing the atmospheric CO2 concentration and producing fuels or/and useful organic compounds at the same time. The most common photocatalysts for the CO2 reduction are the inorganic, the carbon based semiconductors and the hybrids based on semiconductors, which combine stability, low cost and appropriate structure in order to accomplish redox reactions. In this review, inorganic semiconductors such as single-metal oxide, mixed-metal oxides, metal oxide composites, layered double hydroxides (LDHs), salt composites, carbon based semiconductors such as graphene based composites, CNT composites, g-C3N4 composites and hybrid organic-inorganic materials (ZIFs) were studied. TiO2 and Ti based photocatalysts are extensively studied and therefore in this review they are not mentioned.

High efficiency photovoltaic device

DOEpatents

Guha, Subhendu; Yang, Chi C.; Xu, Xi Xiang

1999-11-02

An N-I-P type photovoltaic device includes a multi-layered body of N-doped semiconductor material which has an amorphous, N doped layer in contact with the amorphous body of intrinsic semiconductor material, and a microcrystalline, N doped layer overlying the amorphous, N doped material. A tandem device comprising stacked N-I-P cells may further include a second amorphous, N doped layer interposed between the microcrystalline, N doped layer and a microcrystalline P doped layer. Photovoltaic devices thus configured manifest improved performance, particularly when configured as tandem devices.

Metal-Semiconductor Nanocomposites for High Efficiency Thermoelectric Power Generation

DTIC Science & Technology

2013-12-07

standard III–V compound semiconductor processing techniques with terbium- doped InGaAs of high terbium concentration, Journal of Vacuum Science...even lower the required temperature for strong covalent bonding. We performed the oxide bonding for this substrate transfer task (see Figure 16 for...appropriate controls for assessing ErSb:InGaSb and other nanocomposites of p-type III-V compound semiconductors and their alloys. UCSC group calculated

Dual passivation of intrinsic defects at the compound semiconductor/oxide interface using an oxidant and a reductant.

PubMed

Kent, Tyler; Chagarov, Evgeniy; Edmonds, Mary; Droopad, Ravi; Kummel, Andrew C

2015-05-26

Studies have shown that metal oxide semiconductor field-effect transistors fabricated utilizing compound semiconductors as the channel are limited in their electrical performance. This is attributed to imperfections at the semiconductor/oxide interface which cause electronic trap states, resulting in inefficient modulation of the Fermi level. The physical origin of these states is still debated mainly because of the difficulty in assigning a particular electronic state to a specific physical defect. To gain insight into the exact source of the electronic trap states, density functional theory was employed to model the intrinsic physical defects on the InGaAs (2 × 4) surface and to model the effective passivation of these defects by utilizing both an oxidant and a reductant to eliminate metallic bonds and dangling-bond-induced strain at the interface. Scanning tunneling microscopy and spectroscopy were employed to experimentally determine the physical and electronic defects and to verify the effectiveness of dual passivation with an oxidant and a reductant. While subsurface chemisorption of oxidants on compound semiconductor substrates can be detrimental, it has been shown theoretically and experimentally that oxidants are critical to removing metallic defects at oxide/compound semiconductor interfaces present in nanoscale channels, oxides, and other nanostructures.

Synthesis of chemicals using solar energy with stable photoelectrochemically active heterostructures.

PubMed

Mubeen, Syed; Singh, Nirala; Lee, Joun; Stucky, Galen D; Moskovits, Martin; McFarland, Eric W

2013-05-08

Efficient and cost-effective conversion of solar energy to useful chemicals and fuels could lead to a significant reduction in fossil hydrocarbon use. Artificial systems that use solar energy to produce chemicals have been reported for more than a century. However the most efficient devices demonstrated, based on traditionally fabricated compound semiconductors, have extremely short working lifetimes due to photocorrosion by the electrolyte. Here we report a stable, scalable design and molecular level fabrication strategy to create photoelectrochemically active heterostructure (PAH) units consisting of an efficient semiconductor light absorber in contact with oxidation and reduction electrocatalysts and otherwise protected by alumina. The functional heterostructures are fabricated by layer-by-layer, template-directed, electrochemical synthesis in porous anodic aluminum oxide membranes to produce high density arrays of electronically autonomous, nanostructured, corrosion resistant, photoactive units (~10(9)-10(10) PAHs per cm(2)). Each PAH unit is isolated from its neighbor by the transparent electrically insulating oxide cellular enclosure that makes the overall assembly fault tolerant. When illuminated with visible light, the free floating devices have been demonstrated to produce hydrogen at a stable rate for over 24 h in corrosive hydroiodic acid electrolyte with light as the only input. The quantum efficiency (averaged over the solar spectrum) for absorbed photons-to-hydrogen conversion was 7.4% and solar-to-hydrogen energy efficiency of incident light was 0.9%. The fabrication approach is scalable for commercial manufacturing and readily adaptable to a variety of earth abundant semiconductors which might otherwise be unstable as photoelectrocatalysts.

Real-time x-ray studies of crystal growth modes during metal-organic vapor phase epitaxy of GaN on c- and m-plane single crystals

DOE PAGES

Perret, Edith; Highland, M. J.; Stephenson, G. B.; ...

2014-08-04

Non-polar orientations of III-nitride semiconductors have attracted significant interest due to their potential application in optoelectronic devices with enhanced efficiency. Using in-situ surface x-ray scattering during metal-organic vapor phase epitaxy (MOVPE) of GaN on non-polar (m-plane) and polar (c-plane) orientations of single crystal substrates, we have observed the homoepitaxial growth modes as a function of temperature and growth rate. On the m-plane surface we observe all three growth modes (step-flow, layer-by-layer, and three-dimensional) as conditions are varied. In contrast, the +c-plane surface exhibits a direct cross over between step-flow and 3-D growth, with no layer-by-layer regime. The apparent activation energymore » of 2.8 ± 0.2 eV observed for the growth rate at the layer-by-layer to step-flow boundary on the m-plane surface is consistent with those observed for MOVPE growth of other III-V compounds, indicating a large critical nucleus size for islands.« less

Electronic Properties, Screening, and Efficient Carrier Transport in NaSbS 2

DOE PAGES

Sun, Jifeng; Singh, David J.

2017-02-13

NaSbS 2 is a semiconductor that was recently shown to have remarkable efficacy as a solar absorber indicating efficient charge collection even in material containing defects. We report first-principles calculations of properties that show (1) an indirect gap only slightly smaller than the direct gap, which may impede the recombination of photoexcited carriers, (2) highly anisotropic electronic and optical properties reflecting a layered crystal structure, (3) a pushed-up valence-band maximum due to repulsion from the Sb 5s states, and (4) cross-gap hybridization between the S p—derived valence bands and the Sb 5p states. This latter feature leads to enhanced Bornmore » effective charges that can provide local screening and, therefore, defect tolerance. Finally, these features are discussed in relation to the performance of the compound as a semiconductor with efficient charge collection.« less

Resin bleed improvement on surface mount semiconductor device

NASA Astrophysics Data System (ADS)

Rajoo, Indra Kumar; Tahir, Suraya Mohd; Aziz, Faieza Abdul; Shamsul Anuar, Mohd

2018-04-01

Resin bleed is a transparent layer of epoxy compound which occurs during molding process but is difficult to be detected after the molding process. Resin bleed on the lead on the unit from the focused package, SOD123, can cause solderability failure at end customer. This failed unit from the customer will be considered as a customer complaint. Generally, the semiconductor company has to perform visual inspection after the plating process to detect resin bleed. Mold chase with excess hole, split cavity & stepped design ejector pin hole have been found to be the major root cause of resin bleed in this company. The modifications of the mold chase, changing of split cavity to solid cavity and re-design of the ejector pin proposed were derived after a detailed study & analysis conducted to arrive at these solutions. The solutions proposed have yield good results during the pilot run with zero (0) occurrence of resin bleed for 3 consecutive months.

III-V arsenide-nitride semiconductor

NASA Technical Reports Server (NTRS)

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

2000-01-01

III-V arsenide-nitride semiconductor are disclosed. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V materials varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V material can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Methods for forming group III-arsenide-nitride semiconductor materials

NASA Technical Reports Server (NTRS)

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

2002-01-01

Methods are disclosed for forming Group III-arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Methods for forming group III-V arsenide-nitride semiconductor materials

NASA Technical Reports Server (NTRS)

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

2000-01-01

Methods are disclosed for forming Group III--arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Effect of the waveguide layer thickness on output characteristics of semiconductor lasers with emission wavelength from 1500 to 1600 nm

NASA Astrophysics Data System (ADS)

Marmalyuk, A. A.; Ryaboshtan, Yu L.; Gorlachuk, P. V.; Ladugin, M. A.; Padalitsa, A. A.; Slipchenko, S. O.; Lyutetskiy, A. V.; Veselov, D. A.; Pikhtin, N. A.

2018-03-01

The effect of the waveguide layer thickness on output characteristics of AlGaInAs/InP quantum-well semiconductor lasers is analysed. The samples of semiconductor lasers with narrow and wide waveguides are experimentally fabricated. Their comparison is carried out and the advantages of particular constructions depending on the current pump are demonstrated.

Flat-lying semiconductor-insulator interfacial layer in DNTT thin films.

PubMed

Jung, Min-Cherl; Leyden, Matthew R; Nikiforov, Gueorgui O; Lee, Michael V; Lee, Han-Koo; Shin, Tae Joo; Takimiya, Kazuo; Qi, Yabing

2015-01-28

The molecular order of organic semiconductors at the gate dielectric is the most critical factor determining carrier mobility in thin film transistors since the conducting channel forms at the dielectric interface. Despite its fundamental importance, this semiconductor-insulator interface is not well understood, primarily because it is buried within the device. We fabricated dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) thin film transistors by thermal evaporation in vacuum onto substrates held at different temperatures and systematically correlated the extracted charge mobility to the crystal grain size and crystal orientation. As a result, we identify a molecular layer of flat-lying DNTT molecules at the semiconductor-insulator interface. It is likely that such a layer might form in other material systems as well, and could be one of the factors reducing charge transport. Controlling this interfacial flat-lying layer may raise the ultimate possible device performance for thin film devices.

Wavelength-division multiplexed optical integrated circuit with vertical diffraction grating

NASA Technical Reports Server (NTRS)

Lang, Robert J. (Inventor); Forouhar, Siamak (Inventor)

1994-01-01

A semiconductor optical integrated circuit for wave division multiplexing has a semiconductor waveguide layer, a succession of diffraction grating points in the waveguide layer along a predetermined diffraction grating contour, a semiconductor diode array in the waveguide layer having plural optical ports facing the succession of diffraction grating points along a first direction, respective semiconductor diodes in the array corresponding to respective ones of a predetermined succession of wavelengths, an optical fiber having one end thereof terminated at the waveguide layer, the one end of the optical fiber facing the succession of diffraction grating points along a second direction, wherein the diffraction grating points are spatially distributed along the predetermined contour in such a manner that the succession of diffraction grating points diffracts light of respective ones of the succession of wavelengths between the one end of the optical fiber and corresponding ones of the optical ports.

Dye-sensitized solar cells

DOEpatents

Skotheim, T.A.

1980-03-04

A low-cost dye-sensitized Schottky barrier solar cell is comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent. 3 figs.

Dye-sensitized solar cells

DOEpatents

Skotheim, Terje A. [Berkeley, CA

1980-03-04

A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

Dye-sensitized Schottky barrier solar cells

DOEpatents

Skotheim, Terje A.

1978-01-01

A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

Screening method for selecting semiconductor substrates having defects below a predetermined level in an oxide layer

DOEpatents

Warren, William L.; Vanheusden, Karel J. R.; Schwank, James R.; Fleetwood, Daniel M.; Shaneyfelt, Marty R.; Winokur, Peter S.; Devine, Roderick A. B.

1998-01-01

A method for screening or qualifying semiconductor substrates for integrated circuit fabrication. The method comprises the steps of annealing at least one semiconductor substrate at a first temperature in a defect-activating ambient (e.g. hydrogen, forming gas, or ammonia) for sufficient time for activating any defects within on oxide layer of the substrate; measuring a defect-revealing electrical characteristic of at least a portion of the oxide layer for determining a quantity of activated defects therein; and selecting substrates for which the quantity of activated defects is below a predetermined level. The defect-revealing electrical characteristic may be a capacitance-versus-voltage (C-V) characteristic or a current-versus-voltage (I-V) characteristic that is dependent on an electrical charge in the oxide layer generated by the activated defects. Embodiments of the present invention may be applied for screening any type of semiconductor substrate or wafer having an oxide layer formed thereon or therein. This includes silicon-on-insulator substrates formed by a separation by the implantation of oxygen (SIMOX) process or the bond and etch back silicon-on-insulator (BESOI) process, as well as silicon substrates having a thermal oxide layer or a deposited oxide layer.

Theoretical investigation of the structural, elastic, electronic and optical properties of the ternary indium sulfide layered structures AInS2 (A = K, Rb and Cs)

NASA Astrophysics Data System (ADS)

Bouchenafa, M.; Sidoumou, M.; Halit, M.; Benmakhlouf, A.; Bouhemadou, A.; Maabed, S.; Bentabet, A.; Bin-Omran, S.

2018-02-01

Ab initio calculations were performed to investigate the structural, elastic, electronic and optical properties of the ternary layered systems AInS2 (A = K, Rb and Cs). The calculated structural parameters are in good agreement with the existing experimental data. Analysis of the electronic band structure shows that the three studied materials are direct band-gap semiconductors. Density of states, charge transfers and charge density distribution maps were computed and analyzed. Numerical estimations of the elastic moduli and their related properties for single-crystal and polycrystalline aggregates were predicted. The optical properties were calculated for incident radiation polarized along the [100], [010] and [001] crystallographic directions. The studied materials exhibit a noticeable anisotropic behaviour in the elastic and optical properties, which is expected due to the symmetry and the layered nature of these compounds.

Active layers of high-performance lead zirconate titanate at temperatures compatible with silicon nano- and microelecronic devices

PubMed Central

Bretos, Iñigo; Jiménez, Ricardo; Tomczyk, Monika; Rodríguez-Castellón, Enrique; Vilarinho, Paula M.; Calzada, M. Lourdes

2016-01-01

Applications of ferroelectric materials in modern microelectronics will be greatly encouraged if the thermal incompatibility between inorganic ferroelectrics and semiconductor devices is overcome. Here, solution-processable layers of the most commercial ferroelectric compound ─ morphotrophic phase boundary lead zirconate titanate, namely Pb(Zr0.52Ti0.48)O3 (PZT) ─ are grown on silicon substrates at temperatures well below the standard CMOS process of semiconductor technology. The method, potentially transferable to a broader range of Zr:Ti ratios, is based on the addition of crystalline nanoseeds to photosensitive solutions of PZT resulting in perovskite crystallization from only 350 °C after the enhanced decomposition of metal precursors in the films by UV irradiation. A remanent polarization of 10.0 μC cm−2 is obtained for these films that is in the order of the switching charge densities demanded for FeRAM devices. Also, a dielectric constant of ~90 is measured at zero voltage which exceeds that of current single-oxide candidates for capacitance applications. The multifunctionality of the films is additionally demonstrated by their pyroelectric and piezoelectric performance. The potential integration of PZT layers at such low fabrication temperatures may redefine the concept design of classical microelectronic devices, besides allowing inorganic ferroelectrics to enter the scene of the emerging large-area, flexible electronics. PMID:26837240

Active layers of high-performance lead zirconate titanate at temperatures compatible with silicon nano- and microeletronic [corrected] devices.

PubMed

Bretos, Iñigo; Jiménez, Ricardo; Tomczyk, Monika; Rodríguez-Castellón, Enrique; Vilarinho, Paula M; Calzada, M Lourdes

2016-02-03

Applications of ferroelectric materials in modern microelectronics will be greatly encouraged if the thermal incompatibility between inorganic ferroelectrics and semiconductor devices is overcome. Here, solution-processable layers of the most commercial ferroelectric compound--morphotrophic phase boundary lead zirconate titanate, namely Pb(Zr0.52Ti0.48)O3 (PZT)--are grown on silicon substrates at temperatures well below the standard CMOS process of semiconductor technology. The method, potentially transferable to a broader range of Zr:Ti ratios, is based on the addition of crystalline nanoseeds to photosensitive solutions of PZT resulting in perovskite crystallization from only 350 °C after the enhanced decomposition of metal precursors in the films by UV irradiation. A remanent polarization of 10.0 μC cm(-2) is obtained for these films that is in the order of the switching charge densities demanded for FeRAM devices. Also, a dielectric constant of ~90 is measured at zero voltage which exceeds that of current single-oxide candidates for capacitance applications. The multifunctionality of the films is additionally demonstrated by their pyroelectric and piezoelectric performance. The potential integration of PZT layers at such low fabrication temperatures may redefine the concept design of classical microelectronic devices, besides allowing inorganic ferroelectrics to enter the scene of the emerging large-area, flexible electronics.

Quantum well multijunction photovoltaic cell

DOEpatents

Chaffin, R.J.; Osbourn, G.C.

1983-07-08

A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.

Quantum well multijunction photovoltaic cell

DOEpatents

Chaffin, Roger J.; Osbourn, Gordon C.

1987-01-01

A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.

Multifunctional Organic-Semiconductor Interfacial Layers for Solution-Processed Oxide-Semiconductor Thin-Film Transistor.

PubMed

Kwon, Guhyun; Kim, Keetae; Choi, Byung Doo; Roh, Jeongkyun; Lee, Changhee; Noh, Yong-Young; Seo, SungYong; Kim, Myung-Gil; Kim, Choongik

2017-06-01

The stabilization and control of the electrical properties in solution-processed amorphous-oxide semiconductors (AOSs) is crucial for the realization of cost-effective, high-performance, large-area electronics. In particular, impurity diffusion, electrical instability, and the lack of a general substitutional doping strategy for the active layer hinder the industrial implementation of copper electrodes and the fine tuning of the electrical parameters of AOS-based thin-film transistors (TFTs). In this study, the authors employ a multifunctional organic-semiconductor (OSC) interlayer as a solution-processed thin-film passivation layer and a charge-transfer dopant. As an electrically active impurity blocking layer, the OSC interlayer enhances the electrical stability of AOS TFTs by suppressing the adsorption of environmental gas species and copper-ion diffusion. Moreover, charge transfer between the organic interlayer and the AOS allows the fine tuning of the electrical properties and the passivation of the electrical defects in the AOS TFTs. The development of a multifunctional solution-processed organic interlayer enables the production of low-cost, high-performance oxide semiconductor-based circuits. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mixed ternary heterojunction solar cell

DOEpatents

Chen, Wen S.; Stewart, John M.

1992-08-25

A thin film heterojunction solar cell and a method of making it has a p-type layer of mixed ternary I-III-VI.sub.2 semiconductor material in contact with an n-type layer of mixed binary II-VI semiconductor material. The p-type semiconductor material includes a low resistivity copper-rich region adjacent the back metal contact of the cell and a composition gradient providing a minority carrier mirror that improves the photovoltaic performance of the cell. The p-type semiconductor material preferably is CuInGaSe.sub.2 or CuIn(SSe).sub.2.

Photoelectrochemical cells for conversion of solar energy to electricity and methods of their manufacture

DOEpatents

Skotheim, Terje

1984-04-10

A photoelectric device is disclosed which comprises first and second layers of semiconductive material, each of a different bandgap, with a layer of dry solid polymer electrolyte disposed between the two semiconductor layers. A layer of a polymer blend of a highly conductive polymer and a solid polymer electrolyte is further interposed between the dry solid polymer electrolyte and the first semiconductor layer. A method of manufacturing such devices is also disclosed.

Near single-crystalline, high-carrier-mobility silicon thin film on a polycrystalline/amorphous substrate

DOEpatents

Findikoglu, Alp T [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM; Arendt, Paul N [Los Alamos, NM; Matias, Vladimir [Santa Fe, NM; Choi, Woong [Los Alamos, NM

2009-10-27

A template article including a base substrate including: (i) a base material selected from the group consisting of polycrystalline substrates and amorphous substrates, and (ii) at least one layer of a differing material upon the surface of the base material; and, a buffer material layer upon the base substrate, the buffer material layer characterized by: (a) low chemical reactivity with the base substrate, (b) stability at temperatures up to at least about 800.degree. C. under low vacuum conditions, and (c) a lattice crystal structure adapted for subsequent deposition of a semiconductor material; is provided, together with a semiconductor article including a base substrate including: (i) a base material selected from the group consisting of polycrystalline substrates and amorphous substrates, and (ii) at least one layer of a differing material upon the surface of the base material; and, a buffer material layer upon the base substrate, the buffer material layer characterized by: (a) low chemical reactivity with the base substrate, (b) stability at temperatures up to at least about 800.degree. C. under low vacuum conditions, and (c) a lattice crystal structure adapted for subsequent deposition of a semiconductor material, and, a top-layer of semiconductor material upon the buffer material layer.

Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals

NASA Astrophysics Data System (ADS)

Carey, Benjamin J.; Ou, Jian Zhen; Clark, Rhiannon M.; Berean, Kyle J.; Zavabeti, Ali; Chesman, Anthony S. R.; Russo, Salvy P.; Lau, Desmond W. M.; Xu, Zai-Quan; Bao, Qiaoliang; Kevehei, Omid; Gibson, Brant C.; Dickey, Michael D.; Kaner, Richard B.; Daeneke, Torben; Kalantar-Zadeh, Kourosh

2017-02-01

A variety of deposition methods for two-dimensional crystals have been demonstrated; however, their wafer-scale deposition remains a challenge. Here we introduce a technique for depositing and patterning of wafer-scale two-dimensional metal chalcogenide compounds by transforming the native interfacial metal oxide layer of low melting point metal precursors (group III and IV) in liquid form. In an oxygen-containing atmosphere, these metals establish an atomically thin oxide layer in a self-limiting reaction. The layer increases the wettability of the liquid metal placed on oxygen-terminated substrates, leaving the thin oxide layer behind. In the case of liquid gallium, the oxide skin attaches exclusively to a substrate and is then sulfurized via a relatively low temperature process. By controlling the surface chemistry of the substrate, we produce large area two-dimensional semiconducting GaS of unit cell thickness (~1.5 nm). The presented deposition and patterning method offers great commercial potential for wafer-scale processes.

Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals.

PubMed

Carey, Benjamin J; Ou, Jian Zhen; Clark, Rhiannon M; Berean, Kyle J; Zavabeti, Ali; Chesman, Anthony S R; Russo, Salvy P; Lau, Desmond W M; Xu, Zai-Quan; Bao, Qiaoliang; Kevehei, Omid; Gibson, Brant C; Dickey, Michael D; Kaner, Richard B; Daeneke, Torben; Kalantar-Zadeh, Kourosh

2017-02-17

A variety of deposition methods for two-dimensional crystals have been demonstrated; however, their wafer-scale deposition remains a challenge. Here we introduce a technique for depositing and patterning of wafer-scale two-dimensional metal chalcogenide compounds by transforming the native interfacial metal oxide layer of low melting point metal precursors (group III and IV) in liquid form. In an oxygen-containing atmosphere, these metals establish an atomically thin oxide layer in a self-limiting reaction. The layer increases the wettability of the liquid metal placed on oxygen-terminated substrates, leaving the thin oxide layer behind. In the case of liquid gallium, the oxide skin attaches exclusively to a substrate and is then sulfurized via a relatively low temperature process. By controlling the surface chemistry of the substrate, we produce large area two-dimensional semiconducting GaS of unit cell thickness (∼1.5 nm). The presented deposition and patterning method offers great commercial potential for wafer-scale processes.

Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals

PubMed Central

Carey, Benjamin J.; Ou, Jian Zhen; Clark, Rhiannon M.; Berean, Kyle J.; Zavabeti, Ali; Chesman, Anthony S. R.; Russo, Salvy P.; Lau, Desmond W. M.; Xu, Zai-Quan; Bao, Qiaoliang; Kavehei, Omid; Gibson, Brant C.; Dickey, Michael D.; Kaner, Richard B.; Daeneke, Torben; Kalantar-Zadeh, Kourosh

2017-01-01

A variety of deposition methods for two-dimensional crystals have been demonstrated; however, their wafer-scale deposition remains a challenge. Here we introduce a technique for depositing and patterning of wafer-scale two-dimensional metal chalcogenide compounds by transforming the native interfacial metal oxide layer of low melting point metal precursors (group III and IV) in liquid form. In an oxygen-containing atmosphere, these metals establish an atomically thin oxide layer in a self-limiting reaction. The layer increases the wettability of the liquid metal placed on oxygen-terminated substrates, leaving the thin oxide layer behind. In the case of liquid gallium, the oxide skin attaches exclusively to a substrate and is then sulfurized via a relatively low temperature process. By controlling the surface chemistry of the substrate, we produce large area two-dimensional semiconducting GaS of unit cell thickness (∼1.5 nm). The presented deposition and patterning method offers great commercial potential for wafer-scale processes. PMID:28211538

Method for sputtering a PIN microcrystalline/amorphous silicon semiconductor device with the P and N-layers sputtered from boron and phosphorous heavily doped targets

DOEpatents

Moustakas, Theodore D.; Maruska, H. Paul

1985-04-02

A silicon PIN microcrystalline/amorphous silicon semiconductor device is constructed by the sputtering of N, and P layers of silicon from silicon doped targets and the I layer from an undoped target, and at least one semi-transparent ohmic electrode.

Electrodynamic properties of a hypercrystal with ferrite and semiconductor layers in an external magnetic field

NASA Astrophysics Data System (ADS)

Fedorin, Illia V.

2018-01-01

Electrodynamic properties of a photonic hypercrystal formed by periodically alternating two types of anisotropic metamaterials are studied. The first metamaterial consists of ferrite and dielectric layers, while the second metamaterial consists of semiconductor and dielectric layers. The system is assumed to be placed in an external magnetic field, which applied parallel to the boundaries of the layers. An effective medium theory which is suitable for calculation of properties of long-wavelength electromagnetic modes is applied in order to derive averaged expressions for effective constitutive parameters. It has been shown that providing a conscious choice of the constitutive parameters and material fractions of magnetic, semiconductor, and dielectric layers, the system under study shows hypercrystal properties for both TE and TM waves in the different frequency ranges.

Process for fabricating polycrystalline semiconductor thin-film solar cells, and cells produced thereby

DOEpatents

Wu, Xuanzhi; Sheldon, Peter

2000-01-01

A novel, simplified method for fabricating a thin-film semiconductor heterojunction photovoltaic device includes initial steps of depositing a layer of cadmium stannate and a layer of zinc stannate on a transparent substrate, both by radio frequency sputtering at ambient temperature, followed by the depositing of dissimilar layers of semiconductors such as cadmium sulfide and cadmium telluride, and heat treatment to convert the cadmium stannate to a substantially single-phase material of a spinel crystal structure. Preferably, the cadmium sulfide layer is also deposited by radio frequency sputtering at ambient temperature, and the cadmium telluride layer is deposited by close space sublimation at an elevated temperature effective to convert the amorphous cadmium stannate to the polycrystalline cadmium stannate with single-phase spinel structure.

Architectures and criteria for the design of high efficiency organic photovoltaic cells

DOEpatents

Rand, Barry; Forrest, Stephen R; Pendergrast Burk, Diane

2015-03-31

A method for fabricating an organic photovoltaic cell includes providing a first electrode; depositing a series of at least seven layers onto the first electrode, each layer consisting essentially of a different organic semiconductor material, the organic semiconductor material of at least an intermediate layer of the sequence being a photoconductive material; and depositing a second electrode onto the sequence of at least seven layers. One of the first electrode and the second electrode is an anode and the other is a cathode. The organic semiconductor materials of the series of at least seven layers are arranged to provide a sequence of decreasing lowest unoccupied molecular orbitals (LUMOs) and a sequence of decreasing highest occupied molecular orbitals (HOMOs) across the series from the anode to the cathode.

Charge dissipative dielectric for cryogenic devices

NASA Technical Reports Server (NTRS)

Cantor, Robin Harold (Inventor); Hall, John Addison (Inventor)

2007-01-01

A Superconducting Quantum Interference Device (SQUID) is disclosed comprising a pair of resistively shunted Josephson junctions connected in parallel within a superconducting loop and biased by an external direct current (dc) source. The SQUID comprises a semiconductor substrate and at least one superconducting layer. The metal layer(s) are separated by or covered with a semiconductor material layer having the properties of a conductor at room temperature and the properties of an insulator at operating temperatures (generally less than 100 Kelvins). The properties of the semiconductor material layer greatly reduces the risk of electrostatic discharge that can damage the device during normal handling of the device at room temperature, while still providing the insulating properties desired to allow normal functioning of the device at its operating temperature. A method of manufacturing the SQUID device is also disclosed.

π-π Interaction among violanthrone molecules: observation, enhancement, and resulting charge transport properties.

PubMed

Shi, Min-Min; Chen, Yi; Nan, Ya-Xiong; Ling, Jun; Zuo, Li-Jian; Qiu, Wei-Ming; Wang, Mang; Chen, Hong-Zheng

2011-02-03

To investigate the relationship between π-π stacking and charge transport property of organic semiconductors, a highly soluble violanthrone derivative, 16,17-bis(2-ethylhexyloxy)anthra[9,1,2-cde-]benzo[rst]pentaphene-5,10-dione (3), is designed and synthesized. The π-π stacking behavior and the aggregation of compound 3 in both solution and thin film were studied in detail by (1)H nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-vis) absorption, X-ray diffraction (XRD), and atomic force microscopy (AFM). When (1)H NMR spectroscopy and theoretical modeling results were combined, the arrangements of compound 3 molecules in the aggregates are demonstrated, where the dipole moments of the two adjacent molecules are nearly reversed to achieve efficient intermolecular π-π overlapping. Furthermore, it is interesting to find that the π-π stacking of compound 3, in both solution and thin films, can be enhanced by introducing a poor solvent n-hexane into the dilute chloroform solution. The resulting film exhibits more red-shifted absorption and higher crystallinity than the film made from pure chloroform solvent, suggesting that π-π interactions in the solid state are intensified by the poor solvent. Organic field-effect transistors (OFETs) with compound 3 film as the transportation layer were fabricated. It is disclosed that the compound 3 film obtained from the chloroform/n-hexane mixed solvents exhibits 1 order of magnitude higher hole mobility than that from the pure chloroform solvent because of the enhanced π-π interactions and the higher crystallinity in the former film. This work provided us valuable information in the improvement of electronic and optoelectronic performances of organic semiconductors by tuning their aggregate structures.

Back wall solar cell

NASA Technical Reports Server (NTRS)

Brandhorst, H. W., Jr. (Inventor)

1978-01-01

A solar cell is disclosed which comprises a first semiconductor material of one conductivity type with one face having the same conductivity type but more heavily doped to form a field region arranged to receive the radiant energy to be converted to electrical energy, and a layer of a second semiconductor material, preferably highly doped, of opposite conductivity type on the first semiconductor material adjacent the first semiconductor material at an interface remote from the heavily doped field region. Instead of the opposite conductivity layer, a metallic Schottky diode layer may be used, in which case no additional back contact is needed. A contact such as a gridded contact, previous to the radiant energy may be applied to the heavily doped field region of the more heavily doped, same conductivity material for its contact.

Use of separate ZnTe interface layers to form ohmic contacts to p-CdTe films

DOEpatents

Gessert, T.A.

1999-06-01

A method of is disclosed improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurium-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact. 11 figs.

Use of separate ZnTe interface layers to form OHMIC contacts to p-CdTe films

DOEpatents

Gessert, Timothy A.

1999-01-01

A method of improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurim-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact.

Effect of composition on SILAR deposited CdxZn1-xS thin films

NASA Astrophysics Data System (ADS)

Ashith V., K.; Gowrish Rao, K.

2018-04-01

In the group of II-VI compound semiconductor, cadmium zinc sulphide (CdxZn1-xS) thin films have broad application in photovoltaic, optoelectronic devices etc. For heterojunction aspects, CdxZn1-xS thin film can be used as heterojunction partner for CdTe as the absorber layer. In this work, CdZnS thin films prepared on glass substrates by Successive Ion Layer Adsorption and Reaction (SILAR) method by varying the composition. The XRD patterns of deposited films showed polycrystalline with the hexagonal phase. The crystallite size of the films was estimated from W-H plot. The bond length of the film varied w.r.to the composition of the CdxZn1-xS films. The urbach energy of the films was calcualted from absorbance data.

High-efficiency GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy

PubMed Central

2011-01-01

We report the initial results of GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy (MBE) technique. For GaAs single-junction solar cell, with the application of AlInP as the window layer and GaInP as the back surface field layer, the photovoltaic conversion efficiency of 26% at one sun concentration and air mass 1.5 global (AM1.5G) is realized. The efficiency of 16.4% is also reached for GaInP solar cell. Our results demonstrate that the MBE-grown phosphide-contained III-V compound semiconductor solar cell can be quite comparable to the metal-organic-chemical-vapor-deposition-grown high-efficiency solar cell. PMID:22040124

Thermodynamic properties of semiconductor compounds studied based on Debye-Waller factors

NASA Astrophysics Data System (ADS)

Van Hung, Nguyen; Toan, Nguyen Cong; Ba Duc, Nguyen; Vuong, Dinh Quoc

2015-08-01

Thermodynamic properties of semiconductor compounds have been studied based on Debye-Waller factors (DWFs) described by the mean square displacement (MSD) which has close relation with the mean square relative displacement (MSRD). Their analytical expressions have been derived based on the statistical moment method (SMM) and the empirical many-body Stillinger-Weber potentials. Numerical results for the MSDs of GaAs, GaP, InP, InSb, which have zinc-blende structure, are found to be in reasonable agreement with experiment and other theories. This paper shows that an elements value for MSD is dependent on the binary semiconductor compound within which it resides.

A study of the semiconductor compound СuAlO2 by the method of nuclear quadrupole resonance of Cu

NASA Astrophysics Data System (ADS)

Matukhin, V. L.; Khabibulin, I. Kh.; Shul'gin, D. A.; Smidt, S. V.

2012-07-01

The method of nuclear quadrupole resonance of Cu (NQR Cu) is used to study the samples of a semiconductor compound CuAlO2. The crystal structure of CuAlO2 belongs to the family of delafossite - the mineral of a basic CuFeO2 structure. Transparent semiconductor oxides, such as CuAlO2, have attracted recent attention as promising thermoelectric materials.

The Development of III-V Semiconductor MOSFETs for Future CMOS Applications

NASA Astrophysics Data System (ADS)

Greene, Andrew M.

Alternative channel materials with superior transport properties over conventional strained silicon are required for supply voltage scaling in low power complementary metal-oxide-semiconductor (CMOS) integrated circuits. Group III-V compound semiconductor systems offer a potential solution due to their high carrier mobility, low carrier effective mass and large injection velocity. The enhancement in transistor drive current at a lower overdrive voltage allows for the scaling of supply voltage while maintaining high switching performance. This thesis focuses on overcoming several material and processing challenges associated with III-V semiconductor development including a low thermal processing budget, high interface trap state density (Dit), low resistance source/drain contacts and growth on lattice mismatched substrates. Non-planar In0.53Ga0.47As FinFETs were developed using both "gate-first" and "gate-last" fabrication methods for n-channel MOSFETs. Electron beam lithography and anisotropic plasma etching processes were optimized to create highly scaled fins with near vertical sidewalls. Plasma damage was removed using a wet etch process and improvements in gate efficiency were characterized on MOS capacitor structures. A two-step, selective removal of the pre-grown n+ contact layer was developed for "gate-last" recess etching. The final In0.53Ga 0.47As FinFET devices demonstrated an ION = 70 mA/mm, I ON/IOFF ratio = 15,700 and sub-threshold swing = 210 mV/dec. Bulk GaSb and strained In0.36Ga0.64Sb quantum well (QW) heterostructures were developed for p-channel MOSFETs. Dit was reduced to 2 - 3 x 1012 cm-2eV-1 using an InAs surface layer, (NH4)2S passivation and atomic layer deposition (ALD) of Al2O3. A self-aligned "gate-first" In0.36Ga0.64Sb MOSFET fabrication process was invented using a "T-shaped" electron beam resist patterning stack and intermetallic source/drain contacts. Ni contacts annealed at 300°C demonstrated an ION = 166 mA/mm, ION/IOFF ratio = 1,500 and sub-threshold swing = 340 mV/dec. Split C-V measurements were used to extract an effective channel mobility of muh* = 300 cm2/Vs at Ns = 2 x 1012 cm -2. "Gate-last" MOSFETs grown with an epitaxial p + contact layer were fabricated using selective gate-recess etching techniques. A parasitic "n-channel" limited ION/I OFF ratio and sub-threshold swing, most likely due to effects from the InAs surface layer.

A Designed Room Temperature Multilayered Magnetic Semiconductor

NASA Astrophysics Data System (ADS)

Bouma, Dinah Simone; Charilaou, Michalis; Bordel, Catherine; Duchin, Ryan; Barriga, Alexander; Farmer, Adam; Hellman, Frances; Materials Science Division, Lawrence Berkeley National Lab Team

2015-03-01

A room temperature magnetic semiconductor has been designed and fabricated by using an epitaxial antiferromagnet (NiO) grown in the (111) orientation, which gives surface uncompensated magnetism for an odd number of planes, layered with the lightly doped semiconductor Al-doped ZnO (AZO). Magnetization and Hall effect measurements of multilayers of NiO and AZO are presented for varying thickness of each. The magnetic properties vary as a function of the number of Ni planes in each NiO layer; an odd number of Ni planes yields on each NiO layer an uncompensated moment which is RKKY-coupled to the moments on adjacent NiO layers via the carriers in the AZO. This RKKY coupling oscillates with the AZO layer thickness, and it disappears entirely in samples where the AZO is replaced with undoped ZnO. The anomalous Hall effect data indicate that the carriers in the AZO are spin-polarized according to the direction of the applied field at both low temperature and room temperature. NiO/AZO multilayers are therefore a promising candidate for spintronic applications demanding a room-temperature semiconductor.

Abrupt Depletion Layer Approximation for the Metal Insulator Semiconductor Diode.

ERIC Educational Resources Information Center

Jones, Kenneth

1979-01-01

Determines the excess surface change carrier density, surface potential, and relative capacitance of a metal insulator semiconductor diode as a function of the gate voltage, using the precise questions and the equations derived with the abrupt depletion layer approximation. (Author/GA)

GaN: From three- to two-dimensional single-layer crystal and its multilayer van der Waals solids

NASA Astrophysics Data System (ADS)

Onen, A.; Kecik, D.; Durgun, E.; Ciraci, S.

2016-02-01

Three-dimensional (3D) GaN is a III-V compound semiconductor with potential optoelectronic applications. In this paper, starting from 3D GaN in wurtzite and zinc-blende structures, we investigated the mechanical, electronic, and optical properties of the 2D single-layer honeycomb structure of GaN (g -GaN ) and its bilayer, trilayer, and multilayer van der Waals solids using density-functional theory. Based on high-temperature ab initio molecular-dynamics calculations, we first showed that g -GaN can remain stable at high temperature. Then we performed a comparative study to reveal how the physical properties vary with dimensionality. While 3D GaN is a direct-band-gap semiconductor, g -GaN in two dimensions has a relatively wider indirect band gap. Moreover, 2D g -GaN displays a higher Poisson ratio and slightly less charge transfer from cation to anion. In two dimensions, the optical-absorption spectra of 3D crystalline phases are modified dramatically, and their absorption onset energy is blueshifted. We also showed that the physical properties predicted for freestanding g -GaN are preserved when g -GaN is grown on metallic as well as semiconducting substrates. In particular, 3D layered blue phosphorus, being nearly lattice-matched to g -GaN , is found to be an excellent substrate for growing g -GaN . Bilayer, trilayer, and van der Waals crystals can be constructed by a special stacking sequence of g -GaN , and they can display electronic and optical properties that can be controlled by the number of g -GaN layers. In particular, their fundamental band gap decreases and changes from indirect to direct with an increasing number of g -GaN layers.

Photoprecursor Approach Enables Preparation of Well-Performing Bulk-Heterojunction Layers Comprising a Highly Aggregating Molecular Semiconductor.

PubMed

Suzuki, Mitsuharu; Yamaguchi, Yuji; Takahashi, Kohei; Takahira, Katsuya; Koganezawa, Tomoyuki; Masuo, Sadahiro; Nakayama, Ken-ichi; Yamada, Hiroko

2016-04-06

Active-layer morphology critically affects the performance of organic photovoltaic cells, and thus its optimization is a key toward the achievement of high-efficiency devices. However, the optimization of active-layer morphology is sometimes challenging because of the intrinsic properties of materials such as strong self-aggregating nature or low miscibility. This study postulates that the "photoprecursor approach" can serve as an effective means to prepare well-performing bulk-heterojunction (BHJ) layers containing highly aggregating molecular semiconductors. In the photoprecursor approach, a photoreactive precursor compound is solution-deposited and then converted in situ to a semiconducting material. This study employs 2,6-di(2-thienyl)anthracene (DTA) and [6,6]-phenyl-C71-butyric acid methyl ester as p- and n-type materials, respectively, in which DTA is generated by the photoprecursor approach from the corresponding α-diketone-type derivative DTADK. When only chloroform is used as a cast solvent, the photovoltaic performance of the resulting BHJ films is severely limited because of unfavorable film morphology. The addition of a high-boiling-point cosolvent, o-dichlorobenzene (o-DCB), to the cast solution leads to significant improvement such that the resulting active layers afford up to approximately 5 times higher power conversion efficiencies. The film structure is investigated by two-dimensional grazing-incident wide-angle X-ray diffraction, atomic force microscopy, and fluorescence microspectroscopy to demonstrate that the use of o-DCB leads to improvement in film crystallinity and increase in charge-carrier generation efficiency. The change in film structure is assumed to originate from dynamic molecular motion enabled by the existence of solvent during the in situ photoreaction. The unique features of the photoprecursor approach will be beneficial in extending the material and processing scopes for the development of organic thin-film devices.

Blue/pink/purple electroluminescence from metal-oxide-semiconductor devices fabricated by spin-coating of [tantalum:(gadolinium/praseodymium)] and (praseodymium:cerium) organic compounds on silicon

NASA Astrophysics Data System (ADS)

Ohzone, Takashi; Matsuda, Toshihiro; Fukuoka, Ryouhei; Hattori, Fumihiro; Iwata, Hideyuki

2016-08-01

Blue/pink/purple electroluminescence (EL) from metal-oxide-semiconductor (MOS) devices with an indium tin oxide (ITO)/[Gd/(Ta + Gd/Pr)/(Pr + Ce)-Si-O] insulator layer/n+-Si substrate surface is reported. The insulator layers were fabricated from organic liquid sources of Gd or (Ta + Gd/Pr)/(Pr + Ce) mixtures, which were spin-coated on the n+-Si substrate and annealed at 950 °C for 30 min in air. The EL emission could be observed by the naked eye in the dark in the Fowler-Nordheim (FN) tunnel current regions. Peak wavelengths in the measured EL spectra were independent of the positive current. The EL intensity ratio of ultraviolet (UV) to the visible range varied with the composition ratio of the (Ta + Gd) liquids, and an optimum Ta to Gd ratio existed for the strongest blue emission, which could be attributed to the Ta-related oxide/silicate. The pink EL of the device fabricated with the (\\text{Ta}:\\text{Pr} = 6:4) mixture ratio can be explained by EL emission peaks related to the Pr3+ ions. The purple EL observed from the (\\text{Pr}:\\text{Ce} = 6:4) device corresponds to the strong and broad emission profile near the 357 nm peak, which cannot be assigned to Ce3+ ions. The results suggest that the EL can be attributed to the double-layer oxides with different compositions in the MOS devices. The upper layer consists of various Ta-, Gd-, Pr-, and Ce-related oxides and their silicates, while the lower SiO x -rich layer contributes to the FN current due to the high electric field, and thus the various EL colors.

Gain in three-dimensional metamaterials utilizing semiconductor quantum structures

NASA Astrophysics Data System (ADS)

Schwaiger, Stephan; Klingbeil, Matthias; Kerbst, Jochen; Rottler, Andreas; Costa, Ricardo; Koitmäe, Aune; Bröll, Markus; Heyn, Christian; Stark, Yuliya; Heitmann, Detlef; Mendach, Stefan

2011-10-01

We demonstrate gain in a three-dimensional metal/semiconductor metamaterial by the integration of optically active semiconductor quantum structures. The rolling-up of a metallic structure on top of strained semiconductor layers containing a quantum well allows us to achieve a tightly bent superlattice consisting of alternating layers of lossy metallic and amplifying gain material. We show that the transmission through the superlattice can be enhanced by exciting the quantum well optically under both pulsed or continuous wave excitation. This points out that our structures can be used as a starting point for arbitrary three-dimensional metamaterials including gain.

Screening method for selecting semiconductor substrates having defects below a predetermined level in an oxide layer

DOEpatents

Warren, W.L.; Vanheusden, K.J.R.; Schwank, J.R.; Fleetwood, D.M.; Shaneyfelt, M.R.; Winokur, P.S.; Devine, R.A.B.

1998-07-28

A method is disclosed for screening or qualifying semiconductor substrates for integrated circuit fabrication. The method comprises the steps of annealing at least one semiconductor substrate at a first temperature in a defect-activating ambient (e.g. hydrogen, forming gas, or ammonia) for sufficient time for activating any defects within on oxide layer of the substrate; measuring a defect-revealing electrical characteristic of at least a portion of the oxide layer for determining a quantity of activated defects therein; and selecting substrates for which the quantity of activated defects is below a predetermined level. The defect-revealing electrical characteristic may be a capacitance-versus voltage (C-V) characteristic or a current-versus-voltage (I-V) characteristic that is dependent on an electrical charge in the oxide layer generated by the activated defects. Embodiments of the present invention may be applied for screening any type of semiconductor substrate or wafer having an oxide layer formed thereon or therein. This includes silicon-on-insulator substrates formed by a separation by the implantation of oxygen (SIMOX) process or the bond and etch back silicon-on-insulator (BESOI) process, as well as silicon substrates having a thermal oxide layer or a deposited oxide layer. 5 figs.

Synthesis of freestanding single-crystal perovskite films and heterostructures by etching of sacrificial water-soluble layers

DOE PAGES

Lu, Di; Baek, David J.; Hong, Seung Sae; ...

2016-09-12

Here, the ability to create and manipulate materials in two-dimensional (2D) form has repeatedly had transformative impact on science and technology. In parallel with the exfoliation and stacking of intrinsically layered crystals 1, 2, 3, 4, 5, atomic-scale thin film growth of complex materials has enabled the creation of artificial 2D heterostructures with novel functionality 6, 7, 8, 9 and emergent phenomena, as seen in perovskite heterostructures 10, 11, 12. However, separation of these layers from the growth substrate has proved challenging, limiting the manipulation capabilities of these heterostructures with respect to exfoliated materials. Here we present a general methodmore » to create freestanding perovskite membranes. The key is the epitaxial growth of water-soluble Sr 3Al 2O 6 on perovskite substrates, followed by in situ growth of films and heterostructures. Millimetre-size single-crystalline membranes are produced by etching the Sr 3Al 2O 6 layer in water, providing the opportunity to transfer them to arbitrary substrates and integrate them with heterostructures of semiconductors and layered compounds 13, 14.« less

SLS complementary logic devices with increase carrier mobility

DOEpatents

Chaffin, R.J.; Osbourn, G.C.; Zipperian, T.E.

1991-07-09

In an electronic device comprising a semiconductor material and having at least one performance characteristic which is limited by the mobility of holes in the semiconductor material, said mobility being limited because of a valence band degeneracy among high-mobility and low-mobility energy levels accessible to said holes at the energy-momentum space maximum, an improvement is provided wherein the semiconductor material is a strained layer superlattice (SLS) whose layer compositions and layer thicknesses are selected so that the strain on the layers predominantly containing said at least one carrier type splits said degeneracy and modifies said energy levels around said energy-momentum space maximum in a manner whereby said limitation on the mobility of said holes is alleviated. 5 figures.

SLS complementary logic devices with increase carrier mobility

DOEpatents

Chaffin, Roger J.; Osbourn, Gordon C.; Zipperian, Thomas E.

1991-01-01

In an electronic device comprising a semiconductor material and having at least one performance characteristic which is limited by the mobility of holes in the semiconductor material, said mobility being limited because of a valence band degeneracy among high-mobility and low-mobility energy levels accessible to said holes at the energy-momentum space maximum, an improvement is provided wherein the semiconductor material is a strained layer superlattice (SLS) whose layer compositions and layer thicknesses are selected so that the strain on the layers predominantly containing said at least one carrier type splits said degeneracy and modifies said energy levels around said energy-momentum space maximum in a manner whereby said limitation on the mobility of said holes is alleviated.

Influence of the Surface Layer on the Electrochemical Deposition of Metals and Semiconductors into Mesoporous Silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chubenko, E. B., E-mail: eugene.chubenko@gmail.com; Redko, S. V.; Sherstnyov, A. I.

2016-03-15

The influence of the surface layer on the process of the electrochemical deposition of metals and semiconductors into porous silicon is studied. It is shown that the surface layer differs in structure and electrical characteristics from the host porous silicon bulk. It is established that a decrease in the conductivity of silicon crystallites that form the surface layer of porous silicon has a positive effect on the process of the filling of porous silicon with metals and semiconductors. This is demonstrated by the example of nickel and zinc oxide. The effect can be used for the formation of nanocomposite materialsmore » on the basis of porous silicon and nanostructures with a high aspect ratio.« less

Electrically pumped edge-emitting photonic bandgap semiconductor laser

DOEpatents

Lin, Shawn-Yu; Zubrzycki, Walter J.

2004-01-06

A highly efficient, electrically pumped edge-emitting semiconductor laser based on a one- or two-dimensional photonic bandgap (PBG) structure is described. The laser optical cavity is formed using a pair of PBG mirrors operating in the photonic band gap regime. Transverse confinement is achieved by surrounding an active semiconductor layer of high refractive index with lower-index cladding layers. The cladding layers can be electrically insulating in the passive PBG mirror and waveguide regions with a small conducting aperture for efficient channeling of the injection pump current into the active region. The active layer can comprise a quantum well structure. The quantum well structure can be relaxed in the passive regions to provide efficient extraction of laser light from the active region.

Radiation hardening of metal-oxide semi-conductor (MOS) devices by boron

NASA Technical Reports Server (NTRS)

Danchenko, V.

1974-01-01

Technique using boron effectively protects metal-oxide semiconductor devices from ionizing radiation without using shielding materials. Boron is introduced into insulating gate oxide layer at semiconductor-insulator interface.

Traditional Semiconductors in the Two-Dimensional Limit.

PubMed

Lucking, Michael C; Xie, Weiyu; Choe, Duk-Hyun; West, Damien; Lu, Toh-Ming; Zhang, S B

2018-02-23

Interest in two-dimensional materials has exploded in recent years. Not only are they studied due to their novel electronic properties, such as the emergent Dirac fermion in graphene, but also as a new paradigm in which stacking layers of distinct two-dimensional materials may enable different functionality or devices. Here, through first-principles theory, we reveal a large new class of two-dimensional materials which are derived from traditional III-V, II-VI, and I-VII semiconductors. It is found that in the ultrathin limit the great majority of traditional binary semiconductors studied (a series of 28 semiconductors) are not only kinetically stable in a two-dimensional double layer honeycomb structure, but more energetically stable than the truncated wurtzite or zinc-blende structures associated with three dimensional bulk. These findings both greatly increase the landscape of two-dimensional materials and also demonstrate that in the double layer honeycomb form, even ordinary semiconductors, such as GaAs, can exhibit exotic topological properties.

Controlling the stoichiometry and doping of semiconductor materials

DOEpatents

Albin, David; Burst, James; Metzger, Wyatt; Duenow, Joel; Farrell, Stuart; Colegrove, Eric

2016-08-16

Methods for treating a semiconductor material are provided. According to an aspect of the invention, the method includes annealing the semiconductor material in the presence of a compound that includes a first element and a second element. The first element provides an overpressure to achieve a desired stoichiometry of the semiconductor material, and the second element provides a dopant to the semiconductor material.

Cadmium-free junction fabrication process for CuInSe.sub.2 thin film solar cells

DOEpatents

Ramanathan, Kannan V.; Contreras, Miguel A.; Bhattacharya, Raghu N.; Keane, James; Noufi, Rommel

1999-01-01

The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(b) element such as zinc, and a halide, such as chlorine, and a second layer comprised of a conventional zinc oxide bilayer. A photovoltaic device according the present invention includes a first thin film layer of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer of semiconductor material comprising zinc oxide is then applied in two layers. The first layer comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer of zinc oxide is doped to exhibit low resistivity.

Scalable quantum computer architecture with coupled donor-quantum dot qubits

DOEpatents

Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

2014-08-26

A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

Self-cleaning and surface chemical reactions during hafnium dioxide atomic layer deposition on indium arsenide.

PubMed

Timm, Rainer; Head, Ashley R; Yngman, Sofie; Knutsson, Johan V; Hjort, Martin; McKibbin, Sarah R; Troian, Andrea; Persson, Olof; Urpelainen, Samuli; Knudsen, Jan; Schnadt, Joachim; Mikkelsen, Anders

2018-04-12

Atomic layer deposition (ALD) enables the ultrathin high-quality oxide layers that are central to all modern metal-oxide-semiconductor circuits. Crucial to achieving superior device performance are the chemical reactions during the first deposition cycle, which could ultimately result in atomic-scale perfection of the semiconductor-oxide interface. Here, we directly observe the chemical reactions at the surface during the first cycle of hafnium dioxide deposition on indium arsenide under realistic synthesis conditions using photoelectron spectroscopy. We find that the widely used ligand exchange model of the ALD process for the removal of native oxide on the semiconductor and the simultaneous formation of the first hafnium dioxide layer must be significantly revised. Our study provides substantial evidence that the efficiency of the self-cleaning process and the quality of the resulting semiconductor-oxide interface can be controlled by the molecular adsorption process of the ALD precursors, rather than the subsequent oxide formation.

WOCSDICE 94 - European Workshop on Compound Semiconductor Devices and Integrated Circuits (18th) Held in Kinsale, Ireland on 29 May-1 June 1994

DTIC Science & Technology

1994-06-01

Taskert, M. Demmiler, J. Braunsteint, B. Hughes* and E. SAnchez Dpto. Tecnologfas de las Comunicaciones , Universidad de Vigo, E-36200 Vigo, Spain. Phone...Typical Hall mobilities of MOVPE and MBE grown lattice matched HFET layers 20 InGaAs 10 nm- Vg- 0.4V 60015estimated bulk InA LAs 20 nm 15 sl’,e-rai...P measured 0.3 R measured 1-ti) Rs ~~~0.4 .. .....7. ....... -. C simulated 0.2 C measured 0.1 La ~ ~0.2

Programme and Abstracts. Workshop on Expert Evaluation and Control of Compound Semiconductor Materials and Technologies (1st) Held in Ecole Centrale De Lyon, France on 19 -22 May 1992. (EXAMTEC’ 92)

DTIC Science & Technology

1992-05-22

Evaluation and Control of Compound Semiconductor Materials and Technologies (EXMATEC󈨠) at Ecole Centrale de Lyon (Ecully, France, 19th to 22nd May...semiconductor technologies to manufacture advanced devices with improved reproducibility, better reliability and lower cost. -’Device structures...concepts are required for expert evaluation and control of still developing technologies . In this context, the EXMATEC series will constitute a major

Direct observation of oxygen-vacancy-enhanced polarization in a SrTiO 3-buffered ferroelectric BaTiO 3 film on GaAs

DOE PAGES

Qiao, Q.; Zhang, Y.; Contreras-Guerrero, Rocio; ...

2015-11-16

The integration of functional oxide thin-films on compound semiconductors can lead to a class of reconfigurable spin-based optoelectronic devices if defect-free, fully reversible active layers are stabilized. However, previous first-principles calculations predicted that SrTiO 3 thin filmsgrown on Si exhibit pinned ferroelectric behavior that is not switchable, due to the presence of interfacial vacancies. Meanwhile, piezoresponse force microscopy measurements have demonstrated ferroelectricity in BaTiO 3 grown on semiconductor substrates. The presence of interfacial oxygen vacancies in such complex-oxide/semiconductor systems remains unexplored, and their effect on ferroelectricity is controversial. We also use a combination of aberration-corrected scanning transmission electron microscopy andmore » first-principles density functional theory modeling to examine the role of interfacial oxygen vacancies on the ferroelectricpolarization of a BaTiO 3 thin filmgrown on GaAs. Moreover, we demonstrate that interfacial oxygen vacancies enhance the polar discontinuity (and thus the single domain, out-of-plane polarization pinning in BaTiO 3), and propose that the presence of surface charge screening allows the formation of switchable domains.« less

Digital Alloy Absorber for Photodetectors

NASA Technical Reports Server (NTRS)

Hill, Cory J. (Inventor); Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor)

2016-01-01

In order to increase the spectral response range and improve the mobility of the photo-generated carriers (e.g. in an nBn photodetector), a digital alloy absorber may be employed by embedding one (or fraction thereof) to several monolayers of a semiconductor material (insert layers) periodically into a different host semiconductor material of the absorber layer. The semiconductor material of the insert layer and the host semiconductor materials may have lattice constants that are substantially mismatched. For example, this may performed by periodically embedding monolayers of InSb into an InAsSb host as the absorption region to extend the cutoff wavelength of InAsSb photodetectors, such as InAsSb based nBn devices. The described technique allows for simultaneous control of alloy composition and net strain, which are both key parameters for the photodetector operation.

GUARD RING SEMICONDUCTOR JUNCTION

DOEpatents

Goulding, F.S.; Hansen, W.L.

1963-12-01

A semiconductor diode having a very low noise characteristic when used under reverse bias is described. Surface leakage currents, which in conventional diodes greatly contribute to noise, are prevented from mixing with the desired signal currents. A p-n junction is formed with a thin layer of heavily doped semiconductor material disposed on a lightly doped, physically thick base material. An annular groove cuts through the thin layer and into the base for a short distance, dividing the thin layer into a peripheral guard ring that encircles the central region. Noise signal currents are shunted through the guard ring, leaving the central region free from such currents. (AEC)

Self bleaching photoelectrochemical-electrochromic device

DOEpatents

Bechinger, Clemens S.; Gregg, Brian A.

2002-04-09

A photoelectrochemical-electrochromic device comprising a first transparent electrode and a second transparent electrode in parallel, spaced relation to each other. The first transparent electrode is electrically connected to the second transparent electrode. An electrochromic material is applied to the first transparent electrode and a nanoporous semiconductor film having a dye adsorbed therein is applied to the second transparent electrode. An electrolyte layer contacts the electrochromic material and the nanoporous semiconductor film. The electrolyte layer has a redox couple whereby upon application of light, the nanoporous semiconductor layer dye absorbs the light and the redox couple oxidizes producing an electric field across the device modulating the effective light transmittance through the device.

Mechanisms of Current Transfer in Electrodeposited Layers of Submicron Semiconductor Particles

NASA Astrophysics Data System (ADS)

Zhukov, N. D.; Mosiyash, D. S.; Sinev, I. V.; Khazanov, A. A.; Smirnov, A. V.; Lapshin, I. V.

2017-12-01

Current-voltage ( I- V) characteristics of conductance in multigrain layers of submicron particles of silicon, gallium arsenide, indium arsenide, and indium antimonide have been studied. Nanoparticles of all semiconductors were obtained by processing initial single crystals in a ball mill and applied after sedimentation onto substrates by means of electrodeposition. Detailed analysis of the I- V curves of electrodeposited layers shows that their behavior is determined by the mechanism of intergranular tunneling emission from near-surface electron states of submicron particles. Parameters of this emission process have been determined. The proposed multigrain semiconductor structures can be used in gas sensors, optical detectors, IR imagers, etc.

Semiconductor apparatus utilizing gradient freeze and liquid-solid techniques

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Caillat, Thierry F. (Inventor); Borshchevsky, Alexander (Inventor)

1998-01-01

Transition metals of Group VIII (Co, Rh and Ir) have been prepared as semiconductor compounds with the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freezing techniques and/or liquid phase sintering techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 1200 cm.sup.2.V.sup.-1.s.sup.-1) and good Seebeck coefficients (up to 150 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a substantial increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mascarenhas, Angelo

Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

Two-dimensional layered semiconductor/graphene heterostructures for solar photovoltaic applications.

PubMed

Shanmugam, Mariyappan; Jacobs-Gedrim, Robin; Song, Eui Sang; Yu, Bin

2014-11-07

Schottky barriers formed by graphene (monolayer, bilayer, and multilayer) on 2D layered semiconductor tungsten disulfide (WS2) nanosheets are explored for solar energy harvesting. The characteristics of the graphene-WS2 Schottky junction vary significantly with the number of graphene layers on WS2, resulting in differences in solar cell performance. Compared with monolayer or stacked bilayer graphene, multilayer graphene helps in achieving improved solar cell performance due to superior electrical conductivity. The all-layered-material Schottky barrier solar cell employing WS2 as a photoactive semiconductor exhibits efficient photon absorption in the visible spectral range, yielding 3.3% photoelectric conversion efficiency with multilayer graphene as the Schottky contact. Carrier transport at the graphene/WS2 interface and the interfacial recombination process in the Schottky barrier solar cells are examined.

Proximity charge sensing for semiconductor detectors

DOEpatents

Luke, Paul N; Tindall, Craig S; Amman, Mark

2013-10-08

A non-contact charge sensor includes a semiconductor detector having a first surface and an opposing second surface. The detector includes a high resistivity electrode layer on the first surface and a low resistivity electrode on the high resistivity electrode layer. A portion of the low resistivity first surface electrode is deleted to expose the high resistivity electrode layer in a portion of the area. A low resistivity electrode layer is disposed on the second surface of the semiconductor detector. A voltage applied between the first surface low resistivity electrode and the second surface low resistivity electrode causes a free charge to drift toward the first or second surface according to a polarity of the free charge and the voltage. A charge sensitive preamplifier coupled to a non-contact electrode disposed at a distance from the exposed high resistivity electrode layer outputs a signal in response to movement of free charge within the detector.

Theoretical discovery of stable structures of group III-V monolayers: The materials for semiconductor devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Tatsuo, E-mail: dr.tatsuosuzuki@gmail.com

Group III-V compounds are very important as the materials of semiconductor devices. Stable structures of the monolayers of group III-V binary compounds have been discovered by using first-principles calculations. The primitive unit cell of the discovered structures is a rectangle, which includes four group-III atoms and four group-V atoms. A group-III atom and its three nearest-neighbor group-V atoms are placed on the same plane; however, these connections are not the sp{sup 2} hybridization. The bond angles around the group-V atoms are less than the bond angle of sp{sup 3} hybridization. The discovered structure of GaP is an indirect transition semiconductor,more » while the discovered structures of GaAs, InP, and InAs are direct transition semiconductors. Therefore, the discovered structures of these compounds have the potential of the materials for semiconductor devices, for example, water splitting photocatalysts. The discovered structures may become the most stable structures of monolayers which consist of other materials.« less

High-mobility pyrene-based semiconductor for organic thin-film transistors.

PubMed

Cho, Hyunduck; Lee, Sunyoung; Cho, Nam Sung; Jabbour, Ghassan E; Kwak, Jeonghun; Hwang, Do-Hoon; Lee, Changhee

2013-05-01

Numerous conjugated oligoacenes and polythiophenes are being heavily studied in the search for high-mobility organic semiconductors. Although many researchers have designed fused aromatic compounds as organic semiconductors for organic thin-film transistors (OTFTs), pyrene-based organic semiconductors with high mobilities and on-off current ratios have not yet been reported. Here, we introduce a new pyrene-based p-type organic semiconductor showing liquid crystal behavior. The thin film characteristics of this material are investigated by varying the substrate temperature during the deposition and the gate dielectric condition using the surface modification with a self-assembled monolayer, and systematically studied in correlation with the performances of transistor devices with this compound. OTFT fabricated under the optimum deposition conditions of this compound, namely, 1,6-bis(5'-octyl-2,2'-bithiophen-5-yl)pyrene (BOBTP) shows a high-performance transistor behavior with a field-effect mobility of 2.1 cm(2) V(-1) s(-1) and an on-off current ratio of 7.6 × 10(6) and enhanced long-term stability compared to the pentacene thin-film transistor.

Graphene optical modulator

NASA Astrophysics Data System (ADS)

Liu, Ming; Yin, Xiaobo; Wang, Feng; Zhang, Xiang

2011-10-01

Data communications have been growing at a speed even faster than Moore's Law, with a 44-fold increase expected within the next 10 years. Data Transfer on such scale would have to recruit optical communication technology and inspire new designs of light sources, modulators, and photodetectors. An ideal optical modulator will require high modulation speed, small device footprint and large operating bandwidth. Silicon modulators based on free carrier plasma dispersion effect and compound semiconductors utilizing direct bandgap transition have seen rapid improvement over the past decade. One of the key limitations for using silicon as modulator material is its weak refractive index change, which limits the footprint of silicon Mach-Zehnder interferometer modulators to millimeters. Other approaches such as silicon microring modulators reduce the operation wavelength range to around 100 pm and are highly sensitive to typical fabrication tolerances and temperature fluctuations. Growing large, high quality wafers of compound semiconductors, and integrating them on silicon or other substrates is expensive, which also restricts their commercialization. In this work, we demonstrate that graphene can be used as the active media for electroabsorption modulators. By tuning the Fermi energy level of the graphene layer, we induced changes in the absorption coefficient of graphene at communication wavelength and achieve a modulation depth above 3 dB. This integrated device also has the potential of working at high speed.

Conversion of type of quantum well structure

NASA Technical Reports Server (NTRS)

Ning, Cun-Zheng (Inventor)

2007-01-01

A method for converting a Type 2 quantum well semiconductor material to a Type 1 material. A second layer of undoped material is placed between first and third layers of selectively doped material, which are separated from the second layer by undoped layers having small widths. Doping profiles are chosen so that a first electrical potential increment across a first layer-second layer interface is equal to a first selected value and/or a second electrical potential increment across a second layer-third layer interface is equal to a second selected value. The semiconductor structure thus produced is useful as a laser material and as an incident light detector material in various wavelength regions, such as a mid-infrared region.

Conversion of Type of Quantum Well Structure

NASA Technical Reports Server (NTRS)

Ning, Cun-Zheng (Inventor)

2007-01-01

A method for converting a Type 2 quantum well semiconductor material to a Type 1 material. A second layer of undoped material is placed between first and third layers of selectively doped material, which are separated from the second layer by undoped layers having small widths. Doping profiles are chosen so that a first electrical potential increment across a first layer-second layer interface is equal to a first selected value and/or a second electrical potential increment across a second layer-third layer interface is equal to a second selected value. The semiconductor structure thus produced is useful as a laser material and as an incident light detector material in various wavelength regions, such as a mid-infrared region.

Electrically tunable infrared metamaterial devices

DOEpatents

Brener, Igal; Jun, Young Chul

2015-07-21

A wavelength-tunable, depletion-type infrared metamaterial optical device is provided. The device includes a thin, highly doped epilayer whose electrical permittivity can become negative at some infrared wavelengths. This highly-doped buried layer optically couples with a metamaterial layer. Changes in the transmission spectrum of the device can be induced via the electrical control of this optical coupling. An embodiment includes a contact layer of semiconductor material that is sufficiently doped for operation as a contact layer and that is effectively transparent to an operating range of infrared wavelengths, a thin, highly doped buried layer of epitaxially grown semiconductor material that overlies the contact layer, and a metallized layer overlying the buried layer and patterned as a resonant metamaterial.

Sputter deposition for multi-component thin films

DOEpatents

Krauss, A.R.; Auciello, O.

1990-05-08

Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams. 10 figs.

Sputter deposition for multi-component thin films

DOEpatents

Krauss, Alan R.; Auciello, Orlando

1990-01-01

Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.

Boron, bismuth co-doping of gallium arsenide and other compounds for photonic and heterojunction bipolar transistor devices

DOEpatents

Mascarenhas, Angelo

2015-07-07

Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is sued to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

Thick layered semiconductor devices with water top-gates: High on-off ratio field-effect transistors and aqueous sensors.

PubMed

Huang, Yuan; Sutter, Eli; Wu, Liangmei; Xu, Hong; Bao, Lihong; Gao, Hong-Jun; Zhou, Xingjiang; Sutter, Peter

2018-06-21

Layered semiconductors show promise as channel materials for field-effect transistors (FETs). Usually, such devices incorporate solid back or top gate dielectrics. Here, we explore de-ionized (DI) water as a solution top gate for field-effect switching of layered semiconductors including SnS2, MoS2, and black phosphorus. The DI water gate is easily fabricated, can sustain rapid bias changes, and its efficient coupling to layered materials provides high on-off current ratios, near-ideal sub-threshold swing, and enhanced short-channel behavior even for FETs with thick, bulk-like channels where such control is difficult to realize with conventional back-gating. Screening by the high-k solution gate eliminates hysteresis due to surface and interface trap states and substantially enhances the field-effect mobility. The onset of water electrolysis sets the ultimate limit to DI water gating at large negative gate bias. Measurements in this regime show promise for aqueous sensing, demonstrated here by the amperometric detection of glucose in aqueous solution. DI water gating of layered semiconductors can be harnessed in research on novel materials and devices, and it may with further development find broad applications in microelectronics and sensing.

New NbCd2 Phase in Niobium-Cadmium Coating Films

NASA Astrophysics Data System (ADS)

Volodin, V. N.; Tuleushev, Yu. Zh.; Zhakanbaev, E. A.; Tsai, K. V.; Rofman, O. V.

2018-02-01

Solid solutions in the form of alloy coatings have been obtained for the first time in the Cd concentration range of 64.5% using ion-plasma sputtering and the codeposition of Nb and Cd ultrafine particles. This supports thermal fluctuation melting and the coalescence of fine particles. A coating of niobium and cadmium layers less than 2 nm thick at 68 at % Cd results in the formation of a new phase identified as NbCd2. The tetragonal fcc phase with lattice parameters a = 0.84357 nm and c = 0.54514 nm forms directly during film coating. XRD data for the identification of the intermetallic compound have been determined. The thermal stability of the NbCd 2 intermetallic compound is limited by 200°C. The properties of the synthesized NbCd 2 phase are typical of semiconductors.

A FETISH for gallium arsenide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barron, A.R.

1996-12-31

An overview of the development of a new dielectric material, cubic-GaS, from the synthesis of new organometallic compounds to the fabrication of a new class of gallium arsenide based transistor is presented as a representative example of the possibility that inorganic chemistry can directly effect the development of new semiconductor devices. The gallium sulfido compound [({sup t}Bu)GaS]{sub 4}, readily prepared from tri-tert-butyl gallium, may be used as a precursor for the growth of GaS thin films by metal organic chemical vapor deposition (MOCVD). Photoluminescence and electronic measurements indicate that this material provides a passivation coating for GaAs. Furthermore, the insulatingmore » properties of cubic-GaS make it suitable as the insulating gate layer in a new class of GaAs transistor: a field effect transistor with a sulfide heterojunction (FETISH).« less

Visible-wavelength semiconductor lasers and arrays

DOEpatents

Schneider, Jr., Richard P.; Crawford, Mary H.

1996-01-01

A visible semiconductor laser. The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1.lambda.) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%.

Method for producing a hybridization of detector array and integrated circuit for readout

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Grunthaner, Frank J. (Inventor)

1993-01-01

A process is explained for fabricating a detector array in a layer of semiconductor material on one substrate and an integrated readout circuit in a layer of semiconductor material on a separate substrate in order to select semiconductor material for optimum performance of each structure, such as GaAs for the detector array and Si for the integrated readout circuit. The detector array layer is lifted off its substrate, laminated on the metallized surface on the integrated surface, etched with reticulating channels to the surface of the integrated circuit, and provided with interconnections between the detector array pixels and the integrated readout circuit through the channels. The adhesive material for the lamination is selected to be chemically stable to provide electrical and thermal insulation and to provide stress release between the two structures fabricated in semiconductor materials that may have different coefficients of thermal expansion.

Bulk growth and surface characterization of epitaxy ready cadmium zinc telluride substrates for use in IR imaging applications

NASA Astrophysics Data System (ADS)

Flint, J. P.; Martinez, B.; Betz, T. E. M.; Mackenzie, J.; Kumar, F. J.; Burgess, L.

2017-02-01

Cadmium Zinc Telluride (Cd1-xZnxTe or CZT) is a compound semiconductor substrate material that has been used for infrared detector (IR) applications for many years. CZT is a perfect substrate for the epitaxial growth of Mercury Cadmium Telluride (Hg1-xCdxTe or MCT) epitaxial layers and remains the material of choice for many high performance IR detectors and focal plane arrays that are used to detect across wide IR spectral bands. Critical to the fabrication of high performance MCT IR detectors is a high quality starting CZT substrate, this being a key determinant of epitaxial layer crystallinity, defectivity and ultimately device electro-optical performance. In this work we report on a new source of substrates suitable for IR detector applications, grown using the Travelling Heater Method (THM). This proven method of crystal growth has been used to manufacture high quality IR specification CZT substrates where industry requirements for IR transmission, dislocations, tellurium precipitates and copper impurity levels have been met. Results will be presented for the chemo-mechanical (CMP) polishing of CZT substrates using production tool sets that are identical to those that are used to produce epitaxy-ready surface finishes on related IR compound semiconductor materials such as GaSb and InSb. We will also discuss the requirements to scale CZT substrate manufacture and how with a new III-V like approach to both CZT crystal growth and substrate polishing, we can move towards a more standardized product and one that can ultimately deliver a standard round CZT substrate, as is the case for competing IR materials such as GaSb, InSb and InP.

Tuning negative differential resistance in single-atomic layer boron-silicon sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Ming-Yue; Liu, Chun-Sheng, E-mail: csliu@njupt.edu.cn, E-mail: yanxh@njupt.edu.cn; Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, Jiangsu

2015-03-21

Using density functional theory and nonequilibrium Green's function formalism for quantum transport calculation, we have quantified the ballistic transport properties along different directions in two-dimensional boron-silicon (B-Si) compounds, as well as the current response to bias voltage. The conductance of the most B-Si devices is higher than the conductance of one-atom-thick boron and silicene. Furthermore, the negative differential resistance phenomenon can be found at certain B-Si stoichiometric composition, and it occurs at various bias voltages. Also, the peak-to-valley ratio is sensitive to the B-Si composition and dependent of the direction considered for B-Si monolayers. The present findings could be helpfulmore » for applications of the single-atomic layer B-Si sheets in the field of semiconductor devices or low-dimensional electronic devices.« less

Solid State Research, 1973:2.

DTIC Science & Technology

MERCURY COMPOUNDS, CADMIUM COMPOUNDS, TELLURIDES, NEODYMIUM COMPOUNDS, PHOSPHATES , ELECTRON TRANSITIONS, INFRARED OPTICAL MATERIALS, CRYSTAL GROWTH, MAGNESIUM OXIDES, PHOSPHORESCENT MATERIALS, SEMICONDUCTOR DIODES, MICROELECTRONICS

Tuning and synthesis of semiconductor nanostructures by mechanical compression

DOEpatents

Fan, Hongyou; Li, Binsong

2015-11-17

A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

Method and structure for passivating semiconductor material

DOEpatents

Pankove, Jacques I.

1981-01-01

A structure for passivating semiconductor material comprises a substrate of crystalline semiconductor material, a relatively thin film of carbon disposed on a surface of the crystalline material, and a layer of hydrogenated amorphous silicon deposited on the carbon film.

Uniaxially oriented polycrystalline thin films and air-stable n-type transistors based on donor-acceptor semiconductor (diC8BTBT)(FnTCNQ) [n = 0, 2, 4

NASA Astrophysics Data System (ADS)

Shibata, Yosei; Tsutsumi, Jun'ya; Matsuoka, Satoshi; Matsubara, Koji; Yoshida, Yuji; Chikamatsu, Masayuki; Hasegawa, Tatsuo

2015-04-01

We report the fabrication of high quality thin films for semiconducting organic donor-acceptor charge-transfer (CT) compounds, (diC8BTBT)(FnTCNQ) (diC8BTBT = 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene and FnTCNQ [n = 0,2,4] = fluorinated derivatives of 7,7,8,8,-tetracyanoquinodimethane), which have a high degree of layered crystallinity. Single-phase and uniaxially oriented polycrystalline thin films of the compounds were obtained by co-evaporation of the component donor and acceptor molecules. Organic thin-film transistors (OTFTs) fabricated with the compound films exhibited n-type field-effect characteristics, showing a mobility of 6.9 × 10-2 cm2/V s, an on/off ratio of 106, a sub-threshold swing of 0.8 V/dec, and an excellent stability in air. We discuss the suitability of strong intermolecular donor-acceptor interaction and the narrow CT gap nature in compounds for stable n-type OTFT operation.

Zinc Alloys for the Fabrication of Semiconductor Devices

NASA Technical Reports Server (NTRS)

Ryu, Yungryel; Lee, Tae S.

2009-01-01

ZnBeO and ZnCdSeO alloys have been disclosed as materials for the improvement in performance, function, and capability of semiconductor devices. The alloys can be used alone or in combination to form active photonic layers that can emit over a range of wavelength values. Materials with both larger and smaller band gaps would allow for the fabrication of semiconductor heterostructures that have increased function in the ultraviolet (UV) region of the spectrum. ZnO is a wide band-gap material possessing good radiation-resistance properties. It is desirable to modify the energy band gap of ZnO to smaller values than that for ZnO and to larger values than that for ZnO for use in semiconductor devices. A material with band gap energy larger than that of ZnO would allow for the emission at shorter wavelengths for LED (light emitting diode) and LD (laser diode) devices, while a material with band gap energy smaller than that of ZnO would allow for emission at longer wavelengths for LED and LD devices. The amount of Be in the ZnBeO alloy system can be varied to increase the energy bandgap of ZnO to values larger than that of ZnO. The amount of Cd and Se in the ZnCdSeO alloy system can be varied to decrease the energy band gap of ZnO to values smaller than that of ZnO. Each alloy formed can be undoped or can be p-type doped using selected dopant elements, or can be n-type doped using selected dopant elements. The layers and structures formed with both the ZnBeO and ZnCdSeO semiconductor alloys - including undoped, p-type-doped, and n-type-doped types - can be used for fabricating photonic and electronic semiconductor devices for use in photonic and electronic applications. These devices can be used in LEDs, LDs, FETs (field effect transistors), PN junctions, PIN junctions, Schottky barrier diodes, UV detectors and transmitters, and transistors and transparent transistors. They also can be used in applications for lightemitting display, backlighting for displays, UV and visible transmitters and detectors, high-frequency radar, biomedical imaging, chemical compound identification, molecular identification and structure, gas sensors, imaging systems, and for the fundamental studies of atoms, molecules, gases, vapors, and solids.

Release strategies for making transferable semiconductor structures, devices and device components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, John A.; Nuzzo, Ralph G.; Meitl, Matthew

2016-05-24

Provided are methods for making a device or device component by providing a multi layer structure having a plurality of functional layers and a plurality of release layers and releasing the functional layers from the multilayer structure by separating one or more of the release layers to generate a plurality of transferable structures. The transferable structures are printed onto a device substrate or device component supported by a device substrate. The methods and systems provide means for making high-quality and low-cost photovoltaic devices, transferable semiconductor structures, (opto-)electronic devices and device components.

Controlled growth of semiconductor crystals

DOEpatents

Bourret-Courchesne, Edith D.

1992-01-01

A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

Controlled growth of semiconductor crystals

DOEpatents

Bourret-Courchesne, E.D.

1992-07-21

A method is disclosed for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B[sub x]O[sub y] are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T[sub m1] of the oxide of boron (T[sub m1]=723 K for boron oxide B[sub 2]O[sub 3]), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T[sub m2] of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm[sup 2]. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 [mu]m. 7 figs.

Electroless silver plating of the surface of organic semiconductors.

PubMed

Campione, Marcello; Parravicini, Matteo; Moret, Massimo; Papagni, Antonio; Schröter, Bernd; Fritz, Torsten

2011-10-04

The integration of nanoscale processes and devices demands fabrication routes involving rapid, cost-effective steps, preferably carried out under ambient conditions. The realization of the metal/organic semiconductor interface is one of the most demanding steps of device fabrication, since it requires mechanical and/or thermal treatments which increment costs and are often harmful in respect to the active layer. Here, we provide a microscopic analysis of a room temperature, electroless process aimed at the deposition of a nanostructured metallic silver layer with controlled coverage atop the surface of single crystals and thin films of organic semiconductors. This process relies on the reaction of aqueous AgF solutions with the nonwettable crystalline surface of donor-type organic semiconductors. It is observed that the formation of a uniform layer of silver nanoparticles can be accomplished within 20 min contact time. The electrical characterization of two-terminal devices performed before and after the aforementioned treatment shows that the metal deposition process is associated with a redox reaction causing the p-doping of the semiconductor. © 2011 American Chemical Society

The preparation method of terahertz monolithic integrated device

NASA Astrophysics Data System (ADS)

Zhang, Cong; Su, Bo; He, Jingsuo; Zhang, Hongfei; Wu, Yaxiong; Zhang, Shengbo; Zhang, Cunlin

2018-01-01

The terahertz monolithic integrated device is to integrate the pumping area of the terahertz generation, the detection area of the terahertz receiving and the metal waveguide of terahertz transmission on the same substrate. The terahertz generation and detection device use a photoconductive antenna structure the metal waveguide use a microstrip line structure. The evanescent terahertz-bandwidth electric field extending above the terahertz transmission line interacts with, and is modified by, overlaid dielectric samples, thus enabling the characteristic vibrational absorption resonances in the sample to be probed. In this device structure, since the semiconductor substrate of the photoconductive antenna is located between the strip conductor and the dielectric layer of the microstrip line, and the semiconductor substrate cannot grow on the dielectric layer directly. So how to prepare the semiconductor substrate of the photoconductive antenna and how to bond the semiconductor substrate to the dielectric layer of the microstrip line is a key step in the terahertz monolithic integrated device. In order to solve this critical problem, the epitaxial wafer structure of the two semiconductor substrates is given and transferred to the desired substrate by two methods, respectively.

Optical Computing, 1991, Technical Digest Series, Vol. 6

DTIC Science & Technology

1992-05-22

lasers). Compound semiconductors may satisfy these requirements. For example, optical signal amplification by two-beam coupling and amplified phase... compound semiconductors can provide this type of implementationi. This paper presents results from a detailed investigation on potentials of the...conductivity to achieve high multichannel cell performance. We describe several high performance Gallium Phosphide multichannel Bragg cells which employ these

N-doping of organic semiconductors by bis-metallosandwich compounds

DOEpatents

Barlow, Stephen; Qi, Yabing; Kahn, Antoine; Marder, Seth; Kim, Sang Bok; Mohapatra, Swagat K.; Guo, Song

2016-01-05

The various inventions disclosed, described, and/or claimed herein relate to the field of methods for n-doping organic semiconductors with certain bis-metallosandwich compounds, the doped compositions produced, and the uses of the doped compositions in organic electronic devices. Metals can be manganese, rhenium, iron, ruthenium, osmium, rhodium, or iridium. Stable and efficient doping can be achieved.

Casimir Pressure in Mds-Structures

NASA Astrophysics Data System (ADS)

Yurova, V. A.; Bukina, M. N.; Churkin, Yu. V.; Fedortsov, A. B.; Klimchitskaya, G. L.

2012-07-01

The Casimir pressure on the dielectric layer in metal-dielectric-semiconductor (MDS) structures is calculated in the framework of the Lifshitz theory at nonzero temperature. In this calculation the standard parameters of semiconductor devices with a thin dielectric layer are used. We consider the thickness of a layer decreasing from 40 to 1 nm. At the shortest thickness the Casimir pressure achieves 8 MPa. At small thicknesses the results are compared with the predictions of nonrelativistic theory.

Graphene-on-semiconductor substrates for analog electronics

DOEpatents

Lagally, Max G.; Cavallo, Francesca; Rojas-Delgado, Richard

2016-04-26

Electrically conductive material structures, analog electronic devices incorporating the structures and methods for making the structures are provided. The structures include a layer of graphene on a semiconductor substrate. The graphene layer and the substrate are separated by an interfacial region that promotes transfer of charge carriers from the surface of the substrate to the graphene.

Low temperature junction growth using hot-wire chemical vapor deposition

DOEpatents

Wang, Qi; Page, Matthew; Iwaniczko, Eugene; Wang, Tihu; Yan, Yanfa

2014-02-04

A system and a process for forming a semi-conductor device, and solar cells (10) formed thereby. The process includes preparing a substrate (12) for deposition of a junction layer (14); forming the junction layer (14) on the substrate (12) using hot wire chemical vapor deposition; and, finishing the semi-conductor device.

Method for reducing or eliminating interface defects in mismatched semiconductor epilayers

DOEpatents

Fitzgerald, Jr., Eugene A.; Ast, Dieter G.

1992-01-01

The present invention and process relates to crystal lattice mismatched semiconductor composite having a first semiconductor layer and a second semiconductor growth layer deposited thereon to form an interface wherein the growth layer can be deposited at thicknesses in excess of the critical thickness, even up to about 10.times. critical thickness. Such composite has an interface which is substantially free of interface defects. For example, the size of the growth areas in a mismatched In.sub.0.05 Ga.sub.0.95 As/(001)GaAs interface was controlled by fabricating 2-.mu.m high pillars of various lateral geometries and lateral dimensions before the epitaxial deposition of 3500.ANG. of In.sub.0.05 Ga.sub.0.95 As. The linear dislocation density at the interface was reduced from >5000 dislocations/cm to about zero for 25-.mu.m lateral dimensions and to less than 800 dislocations/cm for lateral dimensions as large as 100 .mu.m. The fabricated pillars control the lateral dimensions of the growth layer and block the glide of misfit dislocations with the resultant decrease in dislocation density.

Method for reducing or eliminating interface defects in mismatched semiconductor eiplayers

DOEpatents

Fitzgerald, Jr., Eugene A.; Ast, Dieter G.

1991-01-01

The present invention and process relates to crystal lattice mismatched semiconductor composite having a first semiconductor layer and a second semiconductor growth layer deposited thereon to form an interface wherein the growth layer can be deposited at thicknesses in excess of the critical thickness, even up to about 10x critical thickness. Such composite has an interface which is substantially free of interface defects. For example, the size of the growth areas in a mismatched In.sub.0.05 Ga.sub.0.95 As/(001)GaAs interface was controlled by fabricating 2-.mu.m high pillars of various lateral geometries and lateral dimensions before the epitaxial deposition of 3500.ANG. of In.sub.0.05 Ga.sub.0.95 As. The linear dislocation density at the interface was reduced from >5000 dislocations/cm to about zero for 25-.mu.m lateral dimensions and to less than 800 dislocations/cm for lateral dimensions as large as 100 .mu.m. The fabricated pillars control the lateral dimensions of the growth layer and block the glide of misfit dislocations with the resultant decrease in dislocation density.

Method for reducing or eliminating interface defects in mismatched semiconductor epilayers

DOEpatents

Fitzgerald, E.A. Jr.; Ast, D.G.

1992-10-20

The present invention and process relates to crystal lattice mismatched semiconductor composite having a first semiconductor layer and a second semiconductor growth layer deposited thereon to form an interface wherein the growth layer can be deposited at thicknesses in excess of the critical thickness, even up to about 10[times] critical thickness. Such composite has an interface which is substantially free of interface defects. For example, the size of the growth areas in a mismatched In[sub 0.05]Ga[sub 0.95]As/(001)GaAs interface was controlled by fabricating 2-[mu]m high pillars of various lateral geometries and lateral dimensions before the epitaxial deposition of 3500 [angstrom] of In[sub 0.05]Ga[sub 0.95]As. The linear dislocation density at the interface was reduced from >5000 dislocations/cm to about zero for 25-[mu]m lateral dimensions and to less than 800 dislocations/cm for lateral dimensions as large as 100 [mu]m. The fabricated pillars control the lateral dimensions of the growth layer and block the glide of misfit dislocations with the resultant decrease in dislocation density. 7 figs.

Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

NASA Astrophysics Data System (ADS)

Held, Martin; Schießl, Stefan P.; Miehler, Dominik; Gannott, Florentina; Zaumseil, Jana

2015-08-01

Transistors for future flexible organic light-emitting diode (OLED) display backplanes should operate at low voltages and be able to sustain high currents over long times without degradation. Hence, high capacitance dielectrics with low surface trap densities are required that are compatible with solution-processable high-mobility semiconductors. Here, we combine poly(methyl methacrylate) (PMMA) and atomic layer deposition hafnium oxide (HfOx) into a bilayer hybrid dielectric for field-effect transistors with a donor-acceptor polymer (DPPT-TT) or single-walled carbon nanotubes (SWNTs) as the semiconductor and demonstrate substantially improved device performances for both. The ultra-thin PMMA layer ensures a low density of trap states at the semiconductor-dielectric interface while the metal oxide layer provides high capacitance, low gate leakage and superior barrier properties. Transistors with these thin (≤70 nm), high capacitance (100-300 nF/cm2) hybrid dielectrics enable low operating voltages (<5 V), balanced charge carrier mobilities and low threshold voltages. Moreover, the hybrid layers substantially improve the bias stress stability of the transistors compared to those with pure PMMA and HfOx dielectrics.

Electronic functions of solid-to-liquid interfaces of organic semiconductor crystals and ionic liquid

NASA Astrophysics Data System (ADS)

Takeya, J.

2008-10-01

The environment of surface electrons at 'solid-to-liquid' interfaces is somewhat extreme, subjected to intense local electric fields or harsh chemical pressures that high-density ionic charge or polarization of mobile molecules create. In this proceedings, we argue functions of electronic carriers generated at the surface of organic semiconductor crystals in response to the local electric fields in the very vicinity of the interface to ionic liquid. The ionic liquids (ILs), or room temperature molten salts, are gaining considerable interest in the recent decade at the prospect of nonvolatile 'green solvents', with the development of chemically stable and nontoxic compounds. Moreover, such materials are also applied to electrolytes for lithium ion batteries and electric double-layer (EDL) capacitors. Our present solid-to-liquid interfaces of rubrene single crystals and ionic liquids work as fast-switching organic field-effect transistors (OFETs) with the highest transconductance, i.e. the most efficient response of the output current to the input voltage, among the OFETs ever built.

III-V aresenide-nitride semiconductor materials and devices

NASA Technical Reports Server (NTRS)

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

1997-01-01

III-V arsenide-nitride semiconductor crystals, methods for producing such crystals and devices employing such crystals. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Synthesis and characterization of thermally evaporated Cu2SnSe3 ternary semiconductor

NASA Astrophysics Data System (ADS)

Hamdani, K.; Chaouche, M.; Benabdeslem, M.; Bechiri, L.; Benslim, N.; Amara, A.; Portier, X.; Bououdina, M.; Otmani, A.; Marie, P.

2014-11-01

Copper Tin Selenide (CuSnSe) powder was mechanically alloyed by high energy planetary ball milling, starting from elemental powders. Synthesis time and velocity have been optimized to produce Cu2SnSe3 materials. Thin films were prepared by thermal evaporation on Corning glass substrate at Ts = 300 °C. The structural, compositional, morphological and optical properties of the synthesized semiconductor have been analyzed by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and transmission electron microscopy. The analyzed powder exhibited a cubic crystal structure, with the presence of Cu2Se as a secondary phase. On the other hand, the deposited films showed a cubic Cu2SnSe3 ternary phase and extra peaks belonging to some binary compounds. Furthermore, optical measurements showed that the deposited layers have a relatively high absorption coefficient of 105 cm-1 and present a band gap of 0.94 eV.

Semiconductor light source with electrically tunable emission wavelength

DOEpatents

Belenky, Gregory [Port Jefferson, NY; Bruno, John D [Bowie, MD; Kisin, Mikhail V [Centereach, NY; Luryi, Serge [Setauket, NY; Shterengas, Leon [Centereach, NY; Suchalkin, Sergey [Centereach, NY; Tober, Richard L [Elkridge, MD

2011-01-25

A semiconductor light source comprises a substrate, lower and upper claddings, a waveguide region with imbedded active area, and electrical contacts to provide voltage necessary for the wavelength tuning. The active region includes single or several heterojunction periods sandwiched between charge accumulation layers. Each of the active region periods comprises higher and lower affinity semiconductor layers with type-II band alignment. The charge carrier accumulation in the charge accumulation layers results in electric field build-up and leads to the formation of generally triangular electron and hole potential wells in the higher and lower affinity layers. Nonequillibrium carriers can be created in the active region by means of electrical injection or optical pumping. The ground state energy in the triangular wells and the radiation wavelength can be tuned by changing the voltage drop across the active region.

Structure and Electrical Conductivity of AgTaS 3

NASA Astrophysics Data System (ADS)

Kim, Changkeun; Yun, Hoseop; Lee, Youngju; Shin, Heekyoon; Liou, Kwangkyoung

1997-09-01

Single crystals of the compound AgTaS 3have been prepared through reactions of the elements with halide mixtures. The structure of AgTaS 3has been analyzed by single-crystal X-ray diffraction methods. AgTaS 3crystallizes in the space group D172h- Cmcmof the orthorhombic system with four formula units in a cell of dimensions a=3.378(2), b=14.070(5), c=7.756(3) Å. The structure of AgTaS 3consists of two-dimensional 2∞[TaS -3] layers separated by Ag +cations. The layer is composed of Ta-centered bicapped trigonal prisms stacked on top of each other by sharing triangular faces. These chains are linked to form the infinite two-dimensional 2∞[TaS -3] slabs. These layers are held together through van der Waals interactions, and Ag +ions reside in the distorted octahedral sites between the layers. The temperature dependence of the electrical conductivity along the needle axis of AgTaS 3shows the typical behavior of an extrinsic semiconductor.

Narrow energy band gap gallium arsenide nitride semi-conductors and an ion-cut-synthesis method for producing the same

DOEpatents

Weng, Xiaojun; Goldman, Rachel S.

2006-06-06

A method for forming a semi-conductor material is provided that comprises forming a donor substrate constructed of GaAs, providing a receiver substrate, implanting nitrogen into the donor substrate to form an implanted layer comprising GaAs and nitrogen. The implanted layer is bonded to the receiver substrate and annealed to form GaAsN and nitrogen micro-blisters in the implanted layer. The micro-blisters allow the implanted layer to be cleaved from the donor substrate.

Hydrogen ion microlithography

DOEpatents

Tsuo, Y. Simon; Deb, Satyen K.

1990-01-01

Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing.

Low resistance barrier layer for isolating, adhering, and passivating copper metal in semiconductor fabrication

DOEpatents

Weihs, Timothy P.; Barbee, Jr., Troy W.

2002-01-01

Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide are deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong (100) texture. Suitable barrier layer materials include refractory transition metal carbides such as vanadium carbide (VC), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr.sub.3 C.sub.2), tungsten carbide (WC), and molybdenum carbide (MoC).

Miniaturized Metal (Metal Alloy)/PdO(x)/SiC Hydrogen and Hydrocarbon Gas Sensors

NASA Technical Reports Server (NTRS)

Hunter, Gary W. (Inventor); Xu, Jennifer C. (Inventor); Lukco, Dorothy (Inventor)

2008-01-01

A miniaturized Schottky diode hydrogen and hydrocarbon sensor and the method of making same is disclosed and claimed. The sensor comprises a catalytic metal layer, such as palladium, a silicon carbide substrate layer and a thin barrier layer in between the catalytic and substrate layers made of palladium oxide (PdO(x)). This highly stable device provides sensitive gas detection at temperatures ranging from at least 450 to 600 C. The barrier layer prevents reactions between the catalytic metal layer and the substrate layer. Conventional semiconductor fabrication techniques are used to fabricate the small-sided sensors. The use of a thicker palladium oxide barrier layer for other semiconductor structures such as a capacitor and transistor structures is also disclosed.

Megahertz organic/polymer diodes

DOEpatents

Katz, Howard Edan; Sun, Jia; Pal, Nath Bhola

2012-12-11

Featured is an organic/polymer diode having a first layer composed essentially of one of an organic semiconductor material or a polymeric semiconductor material and a second layer formed on the first layer and being electrically coupled to the first layer such that current flows through the layers in one direction when a voltage is applied in one direction. The second layer is essentially composed of a material whose characteristics and properties are such that when formed on the first layer, the diode is capable of high frequency rectifications on the order of megahertz rectifications such as for example rectifications at one of above 100KHz, 500KhZ, IMHz, or 10 MHz. In further embodiments, the layers are arranged so as to be exposed to atmosphere.

Photoelectrochemical cell including Ga(Sb.sub.x)N.sub.1-x semiconductor electrode

DOEpatents

Menon, Madhu; Sheetz, Michael; Sunkara, Mahendra Kumar; Pendyala, Chandrashekhar; Sunkara, Swathi; Jasinski, Jacek B.

2017-09-05

The composition of matter comprising Ga(Sb.sub.x)N.sub.1-x where x=0.01 to 0.06 is characterized by a band gap between 2.4 and 1.7 eV. A semiconductor device includes a semiconductor layer of that composition. A photoelectric cell includes that semiconductor device.

Visible light water splitting using dye-sensitized oxide semiconductors.

PubMed

Youngblood, W Justin; Lee, Seung-Hyun Anna; Maeda, Kazuhiko; Mallouk, Thomas E

2009-12-21

Researchers are intensively investigating photochemical water splitting as a means of converting solar to chemical energy in the form of fuels. Hydrogen is a key solar fuel because it can be used directly in combustion engines or fuel cells, or combined catalytically with CO(2) to make carbon containing fuels. Different approaches to solar water splitting include semiconductor particles as photocatalysts and photoelectrodes, molecular donor-acceptor systems linked to catalysts for hydrogen and oxygen evolution, and photovoltaic cells coupled directly or indirectly to electrocatalysts. Despite several decades of research, solar hydrogen generation is efficient only in systems that use expensive photovoltaic cells to power water electrolysis. Direct photocatalytic water splitting is a challenging problem because the reaction is thermodynamically uphill. Light absorption results in the formation of energetic charge-separated states in both molecular donor-acceptor systems and semiconductor particles. Unfortunately, energetically favorable charge recombination reactions tend to be much faster than the slow multielectron processes of water oxidation and reduction. Consequently, visible light water splitting has only recently been achieved in semiconductor-based photocatalytic systems and remains an inefficient process. This Account describes our approach to two problems in solar water splitting: the organization of molecules into assemblies that promote long-lived charge separation, and catalysis of the electrolysis reactions, in particular the four-electron oxidation of water. The building blocks of our artificial photosynthetic systems are wide band gap semiconductor particles, photosensitizer and electron relay molecules, and nanoparticle catalysts. We intercalate layered metal oxide semiconductors with metal nanoparticles. These intercalation compounds, when sensitized with [Ru(bpy)(3)](2+) derivatives, catalyze the photoproduction of hydrogen from sacrificial electron donors (EDTA(2-)) or non-sacrificial donors (I(-)). Through exfoliation of layered metal oxide semiconductors, we construct multilayer electron donor-acceptor thin films or sensitized colloids in which individual nanosheets mediate light-driven electron transfer reactions. When sensitizer molecules are "wired" to IrO(2).nH(2)O nanoparticles, a dye-sensitized TiO(2) electrode becomes the photoanode of a water-splitting photoelectrochemical cell. Although this system is an interesting proof-of-concept, the performance of these cells is still poor (approximately 1% quantum yield) and the dye photodegrades rapidly. We can understand the quantum efficiency and degradation in terms of competing kinetic pathways for water oxidation, back electron transfer, and decomposition of the oxidized dye molecules. Laser flash photolysis experiments allow us to measure these competing rates and, in principle, to improve the performance of the cell by changing the architecture of the electron transfer chain.

Surface and Interface Engineering of Organometallic and Two Dimensional Semiconductor

NASA Astrophysics Data System (ADS)

Park, Jun Hong

For over half a century, inorganic Si and III-V materials have led the modern semiconductor industry, expanding to logic transistor and optoelectronic applications. However, these inorganic materials have faced two different fundamental limitations, flexibility for wearable applications and scaling limitation as logic transistors. As a result, the organic and two dimensional have been studied intentionally for various fields. In the present dissertation, three different studies will be presented with followed order; (1) the chemical response of organic semiconductor in NO2 exposure. (2) The surface and stability of WSe2 in ambient air. (3) Deposition of dielectric on two dimensional materials using organometallic seeding layer. The organic molecules rely on the van der Waals interaction during growth of thin films, contrast to covalent bond inorganic semiconductors. Therefore, the morphology and electronic property at surface of organic semiconductor in micro scale is more sensitive to change in gaseous conditions. In addition, metal phthalocyanine, which is one of organic semiconductor materials, change their electronic property as reaction with gaseous analytes, suggesting as potential chemical sensing platforms. In the present part, the growth behavior of metal phthalocyanine and surface response to gaseous condition will be elucidated using scanning tunneling microscopy (STM). In second part, the surface of layered transition metal dichalcogenides and their chemical response to exposure ambient air will be investigated, using STM. Layered transition metal dichalcogenides (TMDs) have attracted widespread attention in the scientific community for electronic device applications because improved electrostatic gate control and suppression of short channel leakage resulted from their atomic thin body. To fabricate the transistor based on TMDs, TMDs should be exposed to ambient conditions, while the effect of air exposure has not been understood fully. In this part, the effect of ambient air on TMDs will be investigated and partial oxidation of TMDs. In the last part, uniform deposition of dielectric layers on 2D materials will be presented, employing organic seedling layer. Although 2D materials have been expected as next generation semiconductor platform, direct deposition of dielectric is still challenging and induces leakage current commonly, because inertness of their surface resulted from absent of dangling bond. Here, metal phthalocyanine monolayer (ML) is employed as seedling layers and the growth of atomic layer deposition (ALD) dielectric is investigated in each step using STM.

Comparison of Ti/Pd/Ag, Pd/Ti/Pd/Ag and Pd/Ge/Ti/Pd/Ag contacts to n-type GaAs for electronic devices handling high current densities

NASA Astrophysics Data System (ADS)

Huo, Pengyun; Galiana, Beatriz; Rey-Stolle, Ignacio

2017-04-01

In the quest for metal contacts for electronic devices handling high current densities, we report the results of Pd/Ti/Pd/Ag and Pd/Ge/Ti/Pd/Ag contacts to n-GaAs and compare them to Ti/Pd/Ag and AuGe/Ni/Au. These metal systems have been designed with the goal of producing an electrical contact with (a) low metal-semiconductor specific contact resistance, (b) very high sheet conductance, (c) good bondability, (d) long-term durability and (e) cost-effectiveness. The structure of the contacts consists of an interfacial layer (either Pd or Pd/Ge) intended to produce a low metal-semiconductor specific contact resistance; a diffusion barrier (Ti/Pd) and a thick top layer of Ag to provide the desired high sheet conductance, limited cost and good bondability. The results show that both systems can achieve very low metal resistivity (ρ M ˜ 2 × 10-6 Ω cm), reaching values close to that of pure bulk silver. This fact is attributed to the Ti/Pd bilayer acting as an efficient diffusion barrier, and thus the metal sheet resistance can be controlled by the thickness of the deposited silver layer. Moreover, the use of Pd as interfacial layer produces contacts with moderate specific contact resistance (ρ C ˜ 10-4 Ω cm2) whilst the use of Pd/Ge decreases the specific contact resistance to ρ C ˜ 1.5 × 10-7 Ω cm2, as a result of the formation of a Pd4(GaAs, Ge2) compound at the GaAs interface.

Design and fabrication of 6.1-.ANG. family semiconductor devices using semi-insulating A1Sb substrate

DOEpatents

Sherohman, John W [Livermore, CA; Coombs, III, Arthur W.; Yee, Jick Hong [Livermore, CA; Wu, Kuang Jen J [Cupertino, CA

2007-05-29

For the first time, an aluminum antimonide (AlSb) single crystal substrate is utilized to lattice-match to overlying semiconductor layers. The AlSb substrate establishes a new design and fabrication approach to construct high-speed, low-power electronic devices while establishing inter-device isolation. Such lattice matching between the substrate and overlying semiconductor layers minimizes the formation of defects, such as threaded dislocations, which can decrease the production yield and operational life-time of 6.1-.ANG. family heterostructure devices.

Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

PubMed Central

Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

2016-01-01

Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems. PMID:27431769

Growth of Wide Band Gap II-VI Compound Semiconductors by Physical Vapor Transport

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Sha, Yi-Gao

1995-01-01

The studies on the crystal growth and characterization of II-VI wide band gap compound semiconductors, such as ZnTe, CdS, ZnSe and ZnS, have been conducted over the past three decades. The research was not quite as extensive as that on Si, III-V, or even narrow band gap II-VI semiconductors because of the high melting temperatures as well as the specialized applications associated with these wide band gap semiconductors. In the past several years, major advances in the thin film technology such as Molecular Beam Epitaxy (MBE) and Metal Organic Chemical Vapor Deposition (MOCVD) have demonstrated the applications of these materials for the important devices such as light-emitting diode, laser and ultraviolet detectors and the tunability of energy band gap by employing ternary or even quaternary systems of these compounds. At the same time, the development in the crystal growth of bulk materials has not advanced far enough to provide low price, high quality substrates needed for the thin film growth technology.

Emission factors of air toxics from semiconductor manufacturing in Korea.

PubMed

Eom, Yun-Sung; Hong, Ji-Hyung; Lee, Suk-Jo; Lee, Eun-Jung; Cha, Jun-Seok; Lee, Dae-Gyun; Bang, Sun-Ae

2006-11-01

The development of local, accurate emission factors is very important for the estimation of reliable national emissions and air quality management. For that, this study is performed for pollutants released to the atmosphere with source-specific emission tests from the semiconductor manufacturing industry. The semiconductor manufacturing industry is one of the major sources of air toxics or hazardous air pollutants (HAPs); thus, understanding the emission characteristics of the emission source is a very important factor in the development of a control strategy. However, in Korea, there is a general lack of information available on air emissions from the semiconductor industry. The major emission sources of air toxics examined from the semiconductor manufacturing industry were wet chemical stations, coating applications, gaseous operations, photolithography, and miscellaneous devices in the wafer fabrication and semiconductor packaging processes. In this study, analyses of emission characteristics, and the estimations of emission data and factors for air toxics, such as acids, bases, heavy metals, and volatile organic compounds from the semiconductor manufacturing process have been performed. The concentration of hydrogen chloride from the packaging process was the highest among all of the processes. In addition, the emission factor of total volatile organic compounds (TVOCs) for the packaging process was higher than that of the wafer fabrication process. Emission factors estimated in this study were compared with those of Taiwan for evaluation, and they were found to be of similar level in the case of TVOCs and fluorine compounds.

A review of defects and disorder in multinary tetrahedrally bonded semiconductors [Defects and disorder in multinary tetrahedrally bonded semiconductors studied by experiment and theory

DOE PAGES

Baranowski, Lauryn L.; Zawadzki, Pawel; Lany, Stephan; ...

2016-11-10

Defects are critical to understanding the electronic properties of semiconducting compounds, for applications such as light-emitting diodes, transistors, photovoltaics, and thermoelectrics. In this review, we describe our work investigating defects in tetrahedrally bonded, multinary semiconductors, and discuss the place of our research within the context of publications by other groups. We applied experimental and theory techniques to understand point defects, structural disorder, and extended antisite defects in one semiconductor of interest for photovoltaic applications, Cu 2SnS 3. We contrast our findings on Cu 2SnS 3 with other chemically related Cu-Sn-S compounds, as well as structurally related compounds such as Cumore » 2ZnSnS 4 and Cu(In,Ga)Se 2. We find that evaluation of point defects alone is not sufficient to understand defect behavior in multinary tetrahedrally bonded semiconductors. In the case of Cu 2SnS 3 and Cu 2ZnSnS 4, structural disorder and entropy-driven cation clustering can result in nanoscale compositional inhomogeneities which detrimentally impact the electronic transport. Therefore, it is not sufficient to assess only the point defect behavior of new multinary tetrahedrally bonded compounds; effects such as structural disorder and extended antisite defects must also be considered. Altogether, this review provides a framework for evaluating tetrahedrally bonded semiconducting compounds with respect to their defect behavior for photovoltaic and other applications, and suggests new materials that may not be as prone to such imperfections.« less

A review of defects and disorder in multinary tetrahedrally bonded semiconductors [Defects and disorder in multinary tetrahedrally bonded semiconductors studied by experiment and theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baranowski, Lauryn L.; Zawadzki, Pawel; Lany, Stephan

Defects are critical to understanding the electronic properties of semiconducting compounds, for applications such as light-emitting diodes, transistors, photovoltaics, and thermoelectrics. In this review, we describe our work investigating defects in tetrahedrally bonded, multinary semiconductors, and discuss the place of our research within the context of publications by other groups. We applied experimental and theory techniques to understand point defects, structural disorder, and extended antisite defects in one semiconductor of interest for photovoltaic applications, Cu 2SnS 3. We contrast our findings on Cu 2SnS 3 with other chemically related Cu-Sn-S compounds, as well as structurally related compounds such as Cumore » 2ZnSnS 4 and Cu(In,Ga)Se 2. We find that evaluation of point defects alone is not sufficient to understand defect behavior in multinary tetrahedrally bonded semiconductors. In the case of Cu 2SnS 3 and Cu 2ZnSnS 4, structural disorder and entropy-driven cation clustering can result in nanoscale compositional inhomogeneities which detrimentally impact the electronic transport. Therefore, it is not sufficient to assess only the point defect behavior of new multinary tetrahedrally bonded compounds; effects such as structural disorder and extended antisite defects must also be considered. Altogether, this review provides a framework for evaluating tetrahedrally bonded semiconducting compounds with respect to their defect behavior for photovoltaic and other applications, and suggests new materials that may not be as prone to such imperfections.« less

Photodetector with enhanced light absorption

DOEpatents

Kane, James

1985-01-01

A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

Method for sputtering a PIN amorphous silicon semi-conductor device having partially crystallized P and N-layers

DOEpatents

Moustakas, Theodore D.; Maruska, H. Paul

1985-07-09

A high efficiency amorphous silicon PIN semiconductor device having partially crystallized (microcrystalline) P and N layers is constructed by the sequential sputtering of N, I and P layers and at least one semi-transparent ohmic electrode. The method of construction produces a PIN device, exhibiting enhanced electrical and optical properties, improved physical integrity, and facilitates the preparation in a singular vacuum system and vacuum pump down procedure.

Tuneable photonic device including an array of metamaterial resonators

DOEpatents

Brener, Igal; Wanke, Michael; Benz, Alexander

2017-03-14

A photonic apparatus includes a metamaterial resonator array overlying and electromagnetically coupled to a vertically stacked plurality of quantum wells defined in a semiconductor body. An arrangement of electrical contact layers is provided for facilitating the application of a bias voltage across the quantum well stack. Those portions of the semiconductor body that lie between the electrical contact layers are conformed to provide an electrically conductive path between the contact layers and through the quantum well stack.

Apparatus and method of manufacture for an imager equipped with a cross-talk barrier

NASA Technical Reports Server (NTRS)

Pain, Bedabrata (Inventor)

2012-01-01

An imager apparatus and associated starting material are provided. In one embodiment, an imager is provided including a silicon layer of a first conductivity type acting as a junction anode. Such silicon layer is adapted to convert light to photoelectrons. Also included is a semiconductor well of a second conductivity type formed in the silicon layer for acting as a junction cathode. Still yet, a barrier is formed adjacent to the semiconductor well. In another embodiment, a starting material is provided including a first silicon layer and an oxide layer disposed adjacent to the first silicon layer. Also included is a second silicon layer disposed adjacent to the oxide layer opposite the first silicon layer. Such second silicon layer is further equipped with an associated passivation layer and/or barrier.

Technology Roadmaps for Compound Semiconductors

PubMed Central

Bennett, Herbert S.

2000-01-01

The roles cited for compound semiconductors in public versions of existing technology roadmaps from the National Electronics Manufacturing Initiative, Inc., Optoelectronics Industry Development Association, Microelectronics Advanced Research Initiative on Optoelectronic Interconnects, and Optoelectronics Industry and Technology Development Association (OITDA) are discussed and compared within the context of trends in the Si CMOS industry. In particular, the extent to which these technology roadmaps treat compound semiconductors at the materials processing and device levels will be presented for specific applications. For example, OITDA’s Optical Communications Technology Roadmap directly connects the information demand of delivering 100 Mbit/s to the home to the requirement of producing 200 GHz heterojunction bipolar transistors with 30 nm bases and InP high electron mobility transistors with 100 nm gates. Some general actions for progress towards the proposed International Technology Roadmap for Compound Semiconductors (ITRCS) and methods for determining the value of an ITRCS will be suggested. But, in the final analysis, the value added by an ITRCS will depend on how industry leaders respond. The technical challenges and economic opportunities of delivering high quality digital video to consumers provide concrete examples of where the above actions and methods could be applied. PMID:27551615

Observation of turnover of spontaneous polarization in ferroelectric layer of pentacene/poly-(vinylidene-trifluoroethylene) double-layer capacitor under photo illumination by optical second-harmonic generation measurement

NASA Astrophysics Data System (ADS)

Shi, Zhemin; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2016-04-01

The details of turnover process of spontaneous polarization and associated carrier motions in indium-tin oxide/poly-(vinylidene-trifluoroethylene)/pentacene/Au capacitor were analyzed by coupling displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement. A model was set up from DCM results to depict the relationship between electric field in semiconductor layer and applied external voltage, proving that photo illumination effect on the spontaneous polarization process lied in variation of semiconductor conductivity. The EFISHG measurement directly and selectively probed the electric field distribution in semiconductor layer, modifying the model and revealing detailed carrier behaviors involving photo illumination effect, dipole reversal, and interfacial charging in the device. A further decrease of DCM current in the low voltage region under illumination was found as the result of illumination effect, and the result was argued based on the changing of the total capacitance of the double-layer capacitors.

van der Waals epitaxial two-dimensional CdSxSe(1-x) semiconductor alloys with tunable-composition and application to flexible optoelectronics.

PubMed

Xia, Jing; Zhao, Yun-Xuan; Wang, Lei; Li, Xuan-Ze; Gu, Yi-Yi; Cheng, Hua-Qiu; Meng, Xiang-Min

2017-09-21

Despite the substantial progress in the development of two-dimensional (2D) materials from conventional layered crystals, it still remains particularly challenging to produce high-quality 2D non-layered semiconductor alloys which may bring in some unique properties and new functions. In this work, the synthesis of well-oriented 2D non-layered CdS x Se (1-x) semiconductor alloy flakes with tunable compositions and optical properties is established. Structural analysis reveals that the 2D non-layered alloys follow an incommensurate van der Waals epitaxial growth pattern. Photoluminescence measurements show that the 2D alloys have composition-dependent direct bandgaps with the emission peak varying from 1.8 eV to 2.3 eV, coinciding well with the density functional theory calculations. Furthermore, photodetectors based on the CdS x Se (1-x) flakes exhibit a high photoresponsivity of 703 A W -1 with an external quantum efficiency of 1.94 × 10 3 and a response time of 39 ms. Flexible devices fabricated on a thin mica substrate display good mechanical stability upon repeated bending. This work suggests a facile and general method to produce high-quality 2D non-layered semiconductor alloys for next-generation optoelectronic devices.

Method of doping a semiconductor

DOEpatents

Yang, Chiang Y.; Rapp, Robert A.

1983-01-01

A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

Device and method for luminescence enhancement by resonant energy transfer from an absorptive thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akselrod, Gleb M.; Bawendi, Moungi G.; Bulovic, Vladimir

Disclosed are a device and a method for the design and fabrication of the device for enhancing the brightness of luminescent molecules, nanostructures, and thin films. The device includes a mirror, a dielectric medium or spacer, an absorptive layer, and a luminescent layer. The absorptive layer is a continuous thin film of a strongly absorbing organic or inorganic material. The luminescent layer may be a continuous luminescent thin film or an arrangement of isolated luminescent species, e.g., organic or metal-organic dye molecules, semiconductor quantum dots, or other semiconductor nanostructures, supported on top of the absorptive layer.

Method for restoring the resistance of indium oxide semiconductors after heating while in sealed structures

DOEpatents

Seager, C.H.; Evans, J.T. Jr.

1998-11-24

A method is described for counteracting increases in resistivity encountered when Indium Oxide resistive layers are subjected to high temperature annealing steps during semiconductor device fabrication. The method utilizes a recovery annealing step which returns the Indium Oxide layer to its original resistivity after a high temperature annealing step has caused the resistivity to increase. The recovery anneal comprises heating the resistive layer to a temperature between 100 C and 300 C for a period of time that depends on the annealing temperature. The recovery is observed even when the Indium Oxide layer is sealed under a dielectric layer. 1 fig.

Method for restoring the resistance of indium oxide semiconductors after heating while in sealed structures

DOEpatents

Seager, Carleton H.; Evans, Jr., Joseph Tate

1998-01-01

A method for counteracting increases in resistivity encountered when Indium Oxide resistive layers are subjected to high temperature annealing steps during semiconductor device fabrication. The method utilizes a recovery annealing step which returns the Indium Oxide layer to its original resistivity after a high temperature annealing step has caused the resistivity to increase. The recovery anneal comprises heating the resistive layer to a temperature between 100.degree. C. and 300.degree. C. for a period of time that depends on the annealing temperature. The recovery is observed even when the Indium Oxide layer is sealed under a dielectric layer.

Suppression of planar defects in the molecular beam epitaxy of GaAs/ErAs/GaAs heterostructures

NASA Astrophysics Data System (ADS)

Crook, Adam M.; Nair, Hari P.; Ferrer, Domingo A.; Bank, Seth R.

2011-08-01

We present a growth method that overcomes the mismatch in rotational symmetry of ErAs and conventional III-V semiconductors, allowing for epitaxially integrated semimetal/semiconductor heterostructures. Transmission electron microscopy and reflection high-energy electron diffraction reveal defect-free overgrowth of ErAs layers, consisting of >2× the total amount of ErAs that can be embedded with conventional layer-by-layer growth methods. We utilize epitaxial ErAs nanoparticles, overgrown with GaAs, as a seed to grow full films of ErAs. Growth proceeds by diffusion of erbium atoms through the GaAs spacer, which remains registered to the underlying substrate, preventing planar defect formation during subsequent GaAs growth. This growth method is promising for metal/semiconductor heterostructures that serve as embedded Ohmic contacts to epitaxial layers and epitaxially integrated active plasmonic devices.

Conduit for high temperature transfer of molten semiconductor crystalline material

NASA Technical Reports Server (NTRS)

Fiegl, George (Inventor); Torbet, Walter (Inventor)

1983-01-01

A conduit for high temperature transfer of molten semiconductor crystalline material consists of a composite structure incorporating a quartz transfer tube as the innermost member, with an outer thermally insulating layer designed to serve the dual purposes of minimizing heat losses from the quartz tube and maintaining mechanical strength and rigidity of the conduit at the elevated temperatures encountered. The composite structure ensures that the molten semiconductor material only comes in contact with a material (quartz) with which it is compatible, while the outer layer structure reinforces the quartz tube, which becomes somewhat soft at molten semiconductor temperatures. To further aid in preventing cooling of the molten semiconductor, a distributed, electric resistance heater is in contact with the surface of the quartz tube over most of its length. The quartz tube has short end portions which extend through the surface of the semiconductor melt and which are lef bare of the thermal insulation. The heater is designed to provide an increased heat input per unit area in the region adjacent these end portions.

Photodetector having high speed and sensitivity

DOEpatents

Morse, Jeffrey D.; Mariella, Jr., Raymond P.

1991-01-01

The present invention provides a photodetector having an advantageous combination of sensitivity and speed; it has a high sensitivity while retaining high speed. In a preferred embodiment, visible light is detected, but in some embodiments, x-rays can be detected, and in other embodiments infrared can be detected. The present invention comprises a photodetector having an active layer, and a recombination layer. The active layer has a surface exposed to light to be detected, and comprises a semiconductor, having a bandgap graded so that carriers formed due to interaction of the active layer with the incident radiation tend to be swept away from the exposed surface. The graded semiconductor material in the active layer preferably comprises Al.sub.1-x Ga.sub.x As. An additional sub-layer of graded In.sub.1-y Ga.sub.y As may be included between the Al.sub.1-x Ga.sub.x As layer and the recombination layer. The recombination layer comprises a semiconductor material having a short recombination time such as a defective GaAs layer grown in a low temperature process. The recombination layer is positioned adjacent to the active layer so that carriers from the active layer tend to be swept into the recombination layer. In an embodiment, the photodetector may comprise one or more additional layers stacked below the active and recombination layers. These additional layers may include another active layer and another recombination layer to absorb radiation not absorbed while passing through the first layers. A photodetector having a stacked configuration may have enhanced sensitivity and responsiveness at selected wavelengths such as infrared.

Ab initio study of II-(VI)2 dichalcogenides.

PubMed

Olsson, P; Vidal, J; Lincot, D

2011-10-12

The structural stabilities of the (Zn,Cd)(S,Se,Te)(2) dichalcogenides have been determined ab initio. These compounds are shown to be stable in the pyrite phase, in agreement with available experiments. Structural parameters for the ZnTe(2) pyrite semiconductor compound proposed here are presented. The opto-electronic properties of these dichalcogenide compounds have been calculated using quasiparticle GW theory. Bandgaps, band structures and effective masses are proposed as well as absorption coefficients and refraction indices. The compounds are all indirect semiconductors with very flat conduction band dispersion and high absorption coefficients. The work functions and surface properties are predicted. The Te and Se based compounds could be of interest as absorber materials in photovoltaic applications.

Miniaturized metal (metal alloy)/ PdO.sub.x/SiC hydrogen and hydrocarbon gas sensors

NASA Technical Reports Server (NTRS)

Hunter, Gary W. (Inventor); Xu, Jennifer C. (Inventor); Lukco, Dorothy (Inventor)

2011-01-01

A miniaturized Schottky diode hydrogen and hydrocarbon sensor and the method of making same is disclosed and claimed. The sensor comprises a catalytic metal layer, such as palladium, a silicon carbide substrate layer and a thin barrier layer in between the catalytic and substrate layers made of palladium oxide (PdO.sub.x ). This highly stable device provides sensitive gas detection at temperatures ranging from at least 450 to 600.degree. C. The barrier layer prevents reactions between the catalytic metal layer and the substrate layer. Conventional semiconductor fabrication techniques are used to fabricate the small-sized sensors. The use of a thicker palladium oxide barrier layer for other semiconductor structures such as a capacitor and transistor structures is also disclosed.

Miniaturized metal (metal alloy)/ PdO.sub.x/SiC hydrogen and hydrocarbon gas sensors

NASA Technical Reports Server (NTRS)

Xu, Jennifer C. (Inventor); Hunter, Gary W. (Inventor); Lukco, Dorothy (Inventor)

2008-01-01

A miniaturized Schottky diode hydrogen and hydrocarbon sensor and the method of making same is disclosed and claimed. The sensor comprises a catalytic metal layer, such as palladium, a silicon carbide substrate layer and a thin barrier layer in between the catalytic and substrate layers made of palladium oxide (PdO.sub.x). This highly stable device provides sensitive gas detection at temperatures ranging from at least 450 to 600.degree. C. The barrier layer prevents reactions between the catalytic metal layer and the substrate layer. Conventional semiconductor fabrication techniques are used to fabricate the small-sized sensors. The use of a thicker palladium oxide barrier layer for other semiconductor structures such as a capacitor and transistor structures is also disclosed.

Estimation of carrier mobility and charge behaviors of organic semiconductor films in metal-insulator-semiconductor diodes consisting of high-k oxide/organic semiconductor double layers

NASA Astrophysics Data System (ADS)

Chosei, Naoya; Itoh, Eiji

2018-02-01

We have comparatively studied the charge behaviors of organic semiconductor films based on charge extraction by linearly increasing voltage in a metal-insulator-semiconductor (MIS) diode structure (MIS-CELIV) and by classical capacitance-voltage measurement. The MIS-CELIV technique allows the selective measurement of electron and hole mobilities of n- and p-type organic films with thicknesses representative of those of actual devices. We used an anodic oxidized sputtered Ta or Hf electrode as a high-k layer, and it effectively blocked holes at the insulator/semiconductor interface. We estimated the hole mobilities of the polythiophene derivatives regioregular poly(3-hexylthiophene) (P3HT) and poly(3,3‧‧‧-didodecylquarterthiophene) (PQT-12) before and after heat treatment in the ITO/high-k/(thin polymer insulator)/semiconductor/MoO3/Ag device structure. The hole mobility of PQT-12 was improved from 1.1 × 10-5 to 2.1 × 10-5 cm2 V-1 s-1 by the heat treatment of the device at 100 °C for 30 min. An almost two orders of magnitude higher mobility was obtained in MIS diodes with P3HT as the p-type layer. We also determined the capacitance from the displacement current in MIS diodes at a relatively low-voltage sweep, and it corresponded well to the classical capacitance-voltage and frequency measurement results.

Method for making a photodetector with enhanced light absorption

DOEpatents

Kane, James

1987-05-05

A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

Epitaxial growth of CoO films on semiconductor and metal substrates by constructing a complex heterostructure

NASA Astrophysics Data System (ADS)

Entani, S.; Kiguchi, M.; Saiki, K.; Koma, A.

2003-01-01

Epitaxial growth of CoO films was studied using reflection high-energy electron diffraction (RHEED), electron energy loss spectroscopy (EELS), ultraviolet photoelectron spectroscopy (UPS) and Auger electron spectroscopy (AES). The RHEED results indicated that an epitaxial CoO film grew on semiconductor and metal substrates (CoO (0 0 1)∥GaAs (0 0 1), Cu (0 0 1), Ag (0 0 1) and [1 0 0]CoO∥[1 0 0] substrates) by constructing a complex heterostructure with two alkali halide buffer layers. The AES, EELS and UPS results showed that the grown CoO film had almost the same electronic structure as bulk CoO. We could show that use of alkali halide buffer layers was a good way to grow metal oxide films on semiconductor and metal substrates in an O 2 atmosphere. The alkali halide layers not only works as glue to connect very dissimilar materials but also prevents oxidation of metal and semiconductor substrates.

Photoelectrical Stimulation of Neuronal Cells by an Organic Semiconductor-Electrolyte Interface.

PubMed

Abdullaeva, Oliya S; Schulz, Matthias; Balzer, Frank; Parisi, Jürgen; Lützen, Arne; Dedek, Karin; Schiek, Manuela

2016-08-23

As a step toward the realization of neuroprosthetics for vision restoration, we follow an electrophysiological patch-clamp approach to study the fundamental photoelectrical stimulation mechanism of neuronal model cells by an organic semiconductor-electrolyte interface. Our photoactive layer consisting of an anilino-squaraine donor blended with a fullerene acceptor is supporting the growth of the neuronal model cell line (N2A cells) without an adhesion layer on it and is not impairing cell viability. The transient photocurrent signal upon illumination from the semiconductor-electrolyte layer is able to trigger a passive response of the neuronal cells under physiological conditions via a capacitive coupling mechanism. We study the dynamics of the capacitive transmembrane currents by patch-clamp recordings and compare them to the dynamics of the photocurrent signal and its spectral responsivity. Furthermore, we characterize the morphology of the semiconductor-electrolyte interface by atomic force microscopy and study the stability of the interface in dark and under illuminated conditions.

Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations.

PubMed

Yokota, Yasuyuki; Miyamoto, Hiroo; Imanishi, Akihito; Takeya, Jun; Inagaki, Kouji; Morikawa, Yoshitada; Fukui, Ken-Ichi

2018-05-09

Electric double-layer transistors based on ionic liquid/organic semiconductor interfaces have been extensively studied during the past decade because of their high carrier densities at low operation voltages. Microscopic structures and the dynamics of ionic liquids likely determine the device performance; however, knowledge of these is limited by a lack of appropriate experimental tools. In this study, we investigated ionic liquid/organic semiconductor interfaces using molecular dynamics to reveal the microscopic properties of ionic liquids. The organic semiconductors include pentacene, rubrene, fullerene, and 7,7,8,8-tetracyanoquinodimethane (TCNQ). While ionic liquids close to the substrate always form the specific layered structures, the surface properties of organic semiconductors drastically alter the ionic dynamics. Ionic liquids at the fullerene interface behave as a two-dimensional ionic crystal because of the energy gain derived from the favorable electrostatic interaction on the corrugated periodic substrate.

The role of ultra-thin SiO2 layers in metal-insulator-semiconductor (MIS) photoelectrochemical devices (Presentation Recording)

NASA Astrophysics Data System (ADS)

Esposito, Daniel V.

2015-08-01

Solid-state junctions based on a metal-insulator-semiconductor (MIS) architecture are of great interest for a number of optoelectronic applications such as photovoltaics, photoelectrochemical cells, and photodetection. One major advantage of the MIS junction compared to the closely related metal-semiconductor junction, or Schottky junction, is that the thin insulating layer (1-3 nm thick) that separates the metal and semiconductor can significantly reduce the density of undesirable interfacial mid-gap states. The reduction in mid-gap states helps "un-pin" the junction, allowing for significantly higher built-in-voltages to be achieved. A second major advantage of the MIS junction is that the thin insulating layer can also protect the underlying semiconductor from corrosion in an electrochemical environment, making the MIS architecture well-suited for application in (photo)electrochemical applications. In this presentation, discontinuous Si-based MIS junctions immersed in electrolyte are explored for use as i.) photoelectrodes for solar-water splitting in photoelectrochemical cells (PECs) and ii.) position-sensitive photodetectors. The development and optimization of MIS photoelectrodes for both of these applications relies heavily on understanding how processing of the thin SiO2 layer impacts the properties of nano- and micro-scale MIS junctions, as well as the interactions of the insulating layer with the electrolyte. In this work, we systematically explore the effects of insulator thickness, synthesis method, and chemical treatment on the photoelectrochemical and electrochemical properties of these MIS devices. It is shown that electrolyte-induced inversion plays a critical role in determining the charge carrier dynamics within the MIS photoelectrodes for both applications.

Time-of-flight secondary ion mass spectrometry studies of cluster ion analysis for semiconductors and diffusion of manganese in gallium arsenide at low temperatures

NASA Astrophysics Data System (ADS)

Goacher, Robyn Elizabeth

Secondary Ion Mass Spectrometry (SIMS) is an established method for the quantitative analysis of dopants in semiconductors. The quasi-parallel mass acquisition of Time-of-Flight SIMS, along with the development of polyatomic primary ions, have rapidly increased the use of SIMS for analysis of organic and biological specimens. However, the advantages and disadvantages of using cluster primary ions for quantitative analysis of inorganic materials are not clear. The research described in this dissertation investigates the consequences of using polyatomic primary ions for the analysis of inorganic compounds in ToF-SIMS. Furthermore, the diffusion of Mn in GaAs, which is important in Spintronic material applications such as spin injection, is also studied by quantitative ToF-SIMS depth profiling. In the first portion of this work, it was discovered that primary ion bombardment of pre-sputtered compound semiconductors GaAs and InP for the purpose of spectral analysis resulted in the formation of cluster secondary ions, as well as atomic secondary ions (Chapter 2). In particular, bombardment using a cluster primary ion such as Bi3q + or C60q+ resulted in higher yields of high-mass cluster secondary ions. These cluster secondary ions did not have bulk stoichiometry, "non-stoichiometric", in contrast to the paradigm of stoichiometric cluster ions generated from salts. This is attributed to the covalent bonding of the compound semiconductors, as well as to preferential sputtering. The utility of high-mass cluster secondary ions in depth profiling is also discussed. Relative sensitivity factors (RSFs) calculated for ion-implanted Fe and Mn samples in GaAs also exhibit differences based on whether monatomic or polyatomic primary ions are utilized (Chapter 3). These RSFs are important for the quantitative conversion of intensity to concentration. When Bi 32+ primary ions are used for analysis instead of Bi + primary ions, there is a significantly higher proportion of Mn and Fe ions present in the spectra, as referenced to the matrix species. The magnitude of this effect differs depending on the sputtering ion, Cs or C60. The use of C60cluster primary ions for depth profiling of GaAs is also investigated (Chapter 4). In particular, for quantitative depth profiling, parameters such as depth resolution, ion and sputter yields, and relative sensitivity factors are pertinent to profiling thin layered structures quantitatively and quickly. C60 sputtering is compared to Cs sputtering in all of these aspects. It is found that 10 keV C60+ is advantageous for the analysis of metals (such as Au contacts on Si) but that previously reported roughness problems prohibit successful analysis in Si. For Al delta layers and quantum wells in GaAs, C60 q+ sputtering induced very little roughness in the sample, and resulted in high ion yields and excellent signal-to-noise as compared to Cs+ sputtering. However, the depth resolution of C60 is at best equivalent to 1 keV Cs+ and does not extend into the sub 2-nm range. Furthermore, C60 sputtering results in significant carbon implantation. In the second portion of this work, quantitative ToF-SIMS depth profiling was used to evaluate the diffusion of Mn into GaAs. Samples were prepared by Molecular Beam Epitaxy in the department of Physics. Mn diffusion from MnAs was investigated first, and Mn diffusion from layered epitaxial structures of GaAs / Ga1-xMnxAs / GaAs was investigated second. Diffusion experiments were conducted by annealing portions of the samples in sealed glass ampoules at low temperatures (200-400°C). Different sputtering rates were measured for MnAs and GaAs and the measured depth profiles were corrected for these effects. RSFs measured for Mn ion-implanted standards were used to calibrate the intensity scale. For diffusion from MnAs, thin MnAs layers resulted in no measurable changes except in the surface transient. For thick MnAs layers, it was determined that substantial loss of As occurred at 400°C, resulting in severe sample roughening, which inhibited proper SIMS analysis. Results for the diffusion of Mn out of a thick buried layer of Ga1-xMnxAs show that annealing induces diffusion of Mn species from the Ga1-xMnxAs layer into the neighboring GaAs with an activation energy of 0.69+/-0.09 eV. This results in doping of the GaAs layer, which is detrimental to spin injection for Spintronics devices.

Pulsed energy synthesis and doping of silicon carbide

DOEpatents

Truher, J.B.; Kaschmitter, J.L.; Thompson, J.B.; Sigmon, T.W.

1995-06-20

A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate is disclosed, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27--730 C is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including HETEROJUNCTION-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

Pulsed energy synthesis and doping of silicon carbide

DOEpatents

Truher, Joel B.; Kaschmitter, James L.; Thompson, Jesse B.; Sigmon, Thomas W.

1995-01-01

A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27.degree.-730.degree. C. is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including hetero-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

Integrated resonant micro-optical gyroscope and method of fabrication

DOEpatents

Vawter, G Allen [Albuquerque, NM; Zubrzycki, Walter J [Sandia Park, NM; Guo, Junpeng [Albuquerque, NM; Sullivan, Charles T [Albuquerque, NM

2006-09-12

An integrated optic gyroscope is disclosed which is based on a photonic integrated circuit (PIC) having a bidirectional laser source, a pair of optical waveguide phase modulators and a pair of waveguide photodetectors. The PIC can be connected to a passive ring resonator formed either as a coil of optical fiber or as a coiled optical waveguide. The lasing output from each end of the bidirectional laser source is phase modulated and directed around the passive ring resonator in two counterpropagating directions, with a portion of the lasing output then being detected to determine a rotation rate for the integrated optical gyroscope. The coiled optical waveguide can be formed on a silicon, glass or quartz substrate with a silicon nitride core and a silica cladding, while the PIC includes a plurality of III V compound semiconductor layers including one or more quantum well layers which are disordered in the phase modulators and to form passive optical waveguides.

Hydrogen ion microlithography

DOEpatents

Tsuo, Y.S.; Deb, S.K.

1990-10-02

Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing. 6 figs.

Improved method of preparing p-i-n junctions in amorphous silicon semiconductors

DOEpatents

Madan, A.

1984-12-10

A method of preparing p/sup +/-i-n/sup +/ junctions for amorphous silicon semiconductors includes depositing amorphous silicon on a thin layer of trivalent material, such as aluminum, indium, or gallium at a temperature in the range of 200/sup 0/C to 250/sup 0/C. At this temperature, the layer of trivalent material diffuses into the amorphous silicon to form a graded p/sup +/-i junction. A layer of n-type doped material is then deposited onto the intrinsic amorphous silicon layer in a conventional manner to finish forming the p/sup +/-i-n/sup +/ junction.

Release strategies for making transferable semiconductor structures, devices and device components

DOEpatents

Rogers, John A; Nuzzo, Ralph G; Meitl, Matthew; Ko, Heung Cho; Yoon, Jongseung; Menard, Etienne; Baca, Alfred J

2014-11-25

Provided are methods for making a device or device component by providing a multilayer structure having a plurality of functional layers and a plurality of release layers and releasing the functional layers from the multilayer structure by separating one or more of the release layers to generate a plurality of transferable structures. The transferable structures are printed onto a device substrate or device component supported by a device substrate. The methods and systems provide means for making high-quality and low-cost photovoltaic devices, transferable semiconductor structures, (opto-)electronic devices and device components.

Release strategies for making transferable semiconductor structures, devices and device components

DOEpatents

Rogers, John A [Champaign, IL; Nuzzo, Ralph G [Champaign, IL; Meitl, Matthew [Raleigh, NC; Ko, Heung Cho [Urbana, IL; Yoon, Jongseung [Urbana, IL; Menard, Etienne [Durham, NC; Baca, Alfred J [Urbana, IL

2011-04-26

Provided are methods for making a device or device component by providing a multilayer structure having a plurality of functional layers and a plurality of release layers and releasing the functional layers from the multilayer structure by separating one or more of the release layers to generate a plurality of transferable structures. The transferable structures are printed onto a device substrate or device component supported by a device substrate. The methods and systems provide means for making high-quality and low-cost photovoltaic devices, transferable semiconductor structures, (opto-)electronic devices and device components.

Novel nano-semiconductor film layer supported nano-Pd Complex Nanostructured Catalyst Pd/Ⓕ-MeOx/AC for High Efficient Selective Hydrogenation of Phenol to Cyclohexanone.

PubMed

Si, Jiaqi; Ouyang, Wenbing; Zhang, Yanji; Xu, Wentao; Zhou, Jicheng

2017-04-28

Supported metal as a type of heterogeneous catalysts are the most widely used in industrial processes. High dispersion of the metal particles of supported catalyst is a key factor in determining the performance of such catalysts. Here we report a novel catalyst Pd/Ⓕ-MeO x /AC with complex nanostructured, Pd nanoparticles supported on the platelike nano-semiconductor film/activated carbon, prepared by the photocatalytic reduction method, which exhibited high efficient catalytic performance for selective hydrogenation of phenol to cyclohexanone. Conversion of phenol achieved up to more than 99% with a lower mole ratio (0.5%) of active components Pd and phenol within 2 h at 70 °C. The synergistic effect of metal nanoparticles and nano-semiconductors support layer and the greatly increasing of contact interface of nano-metal-semiconductors may be responsible for the high efficiency. This work provides a clear demonstration that complex nanostructured catalysts with nano-metal and nano-semiconductor film layer supported on high specific surface AC can yield enhanced catalytic activity and can afford promising approach for developing new supported catalyst.

Initiation of explosive conversions in energy-saturated nanoporous silicon-based compounds with fast semiconductor switches and energy-releasing elements

NASA Astrophysics Data System (ADS)

Savenkov, G. G.; Kardo-Sysoev, A. F.; Zegrya, A. G.; Os'kin, I. A.; Bragin, V. A.; Zegrya, G. G.

2017-10-01

The first findings concerning the initiation of explosive conversions in energy-saturated nanoporous silicon-based compounds via the electrical explosion of a semiconductor bridge are presented. The obtained results indicate that the energy parameters of an explosive conversion depend on the mass of a combustible agent—namely, nanoporous silicon—and the silicon-doping type.

Reducing dislocations in semiconductors utilizing repeated thermal cycling during multistage epitaxial growth

DOEpatents

Fan, John C. C.; Tsaur, Bor-Yeu; Gale, Ronald P.; Davis, Frances M.

1992-02-25

Dislocation densities are reduced in growing semiconductors from the vapor phase by employing a technique of interrupting growth, cooling the layer so far deposited, and then repeating the process until a high quality active top layer is achieved. The method of interrupted growth, coupled with thermal cycling, permits dislocations to be trapped in the initial stages of epitaxial growth.

Reducing dislocations in semiconductors utilizing repeated thermal cycling during multistage epitaxial growth

DOEpatents

Fan, John C. C.; Tsaur, Bor-Yeu; Gale, Ronald P.; Davis, Frances M.

1986-12-30

Dislocation densities are reduced in growing semiconductors from the vapor phase by employing a technique of interrupting growth, cooling the layer so far deposited, and then repeating the process until a high quality active top layer is achieved. The method of interrupted growth, coupled with thermal cycling, permits dislocations to be trapped in the initial stages of epitaxial growth.

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

PubMed Central

Mei, Yaochuan; Diemer, Peter J.; Niazi, Muhammad R.; Hallani, Rawad K.; Jarolimek, Karol; Day, Cynthia S.; Risko, Chad; Anthony, John E.; Amassian, Aram

2017-01-01

The temperature dependence of the charge-carrier mobility provides essential insight into the charge transport mechanisms in organic semiconductors. Such knowledge imparts critical understanding of the electrical properties of these materials, leading to better design of high-performance materials for consumer applications. Here, we present experimental results that suggest that the inhomogeneous strain induced in organic semiconductor layers by the mismatch between the coefficients of thermal expansion (CTE) of the consecutive device layers of field-effect transistors generates trapping states that localize charge carriers. We observe a universal scaling between the activation energy of the transistors and the interfacial thermal expansion mismatch, in which band-like transport is observed for similar CTEs, and activated transport otherwise. Our results provide evidence that a high-quality semiconductor layer is necessary, but not sufficient, to obtain efficient charge-carrier transport in devices, and underline the importance of holistic device design to achieve the intrinsic performance limits of a given organic semiconductor. We go on to show that insertion of an ultrathin CTE buffer layer mitigates this problem and can help achieve band-like transport on a wide range of substrate platforms. PMID:28739934

Probing dynamic behavior of electric fields and band diagrams in complex semiconductor heterostructures

NASA Astrophysics Data System (ADS)

Turkulets, Yury; Shalish, Ilan

2018-01-01

Modern bandgap engineered electronic devices are typically made of multi-semiconductor multi-layer heterostructures that pose a major challenge to silicon-era characterization methods. As a result, contemporary bandgap engineering relies mostly on simulated band structures that are hardly ever verified experimentally. Here, we present a method that experimentally evaluates bandgap, band offsets, and electric fields, in complex multi-semiconductor layered structures, and it does so simultaneously in all the layers. The method uses a modest optical photocurrent spectroscopy setup at ambient conditions. The results are analyzed using a simple model for electro-absorption. As an example, we apply the method to a typical GaN high electron mobility transistor structure. Measurements under various external electric fields allow us to experimentally construct band diagrams, not only at equilibrium but also under any other working conditions of the device. The electric fields are then used to obtain the charge carrier density and mobility in the quantum well as a function of the gate voltage over the entire range of operating conditions of the device. The principles exemplified here may serve as guidelines for the development of methods for simultaneous characterization of all the layers in complex, multi-semiconductor structures.

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps.

PubMed

Mei, Yaochuan; Diemer, Peter J; Niazi, Muhammad R; Hallani, Rawad K; Jarolimek, Karol; Day, Cynthia S; Risko, Chad; Anthony, John E; Amassian, Aram; Jurchescu, Oana D

2017-08-15

The temperature dependence of the charge-carrier mobility provides essential insight into the charge transport mechanisms in organic semiconductors. Such knowledge imparts critical understanding of the electrical properties of these materials, leading to better design of high-performance materials for consumer applications. Here, we present experimental results that suggest that the inhomogeneous strain induced in organic semiconductor layers by the mismatch between the coefficients of thermal expansion (CTE) of the consecutive device layers of field-effect transistors generates trapping states that localize charge carriers. We observe a universal scaling between the activation energy of the transistors and the interfacial thermal expansion mismatch, in which band-like transport is observed for similar CTEs, and activated transport otherwise. Our results provide evidence that a high-quality semiconductor layer is necessary, but not sufficient, to obtain efficient charge-carrier transport in devices, and underline the importance of holistic device design to achieve the intrinsic performance limits of a given organic semiconductor. We go on to show that insertion of an ultrathin CTE buffer layer mitigates this problem and can help achieve band-like transport on a wide range of substrate platforms.

Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Held, Martin; Schießl, Stefan P.; Gannott, Florentina

Transistors for future flexible organic light-emitting diode (OLED) display backplanes should operate at low voltages and be able to sustain high currents over long times without degradation. Hence, high capacitance dielectrics with low surface trap densities are required that are compatible with solution-processable high-mobility semiconductors. Here, we combine poly(methyl methacrylate) (PMMA) and atomic layer deposition hafnium oxide (HfO{sub x}) into a bilayer hybrid dielectric for field-effect transistors with a donor-acceptor polymer (DPPT-TT) or single-walled carbon nanotubes (SWNTs) as the semiconductor and demonstrate substantially improved device performances for both. The ultra-thin PMMA layer ensures a low density of trap states atmore » the semiconductor-dielectric interface while the metal oxide layer provides high capacitance, low gate leakage and superior barrier properties. Transistors with these thin (≤70 nm), high capacitance (100–300 nF/cm{sup 2}) hybrid dielectrics enable low operating voltages (<5 V), balanced charge carrier mobilities and low threshold voltages. Moreover, the hybrid layers substantially improve the bias stress stability of the transistors compared to those with pure PMMA and HfO{sub x} dielectrics.« less

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures.

PubMed

Chen, Ruei-San; Tang, Chih-Che; Shen, Wei-Chu; Huang, Ying-Sheng

2015-12-05

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal-semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω(-) (1) cm(-) (1), with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

PubMed Central

Chen, Ruei-San; Tang, Chih-Che; Shen, Wei-Chu; Huang, Ying-Sheng

2015-01-01

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal–semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω−1 cm−1, with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2. PMID:26710105

MBE Growth of Ferromagnetic Metal/Compound Semiconductor Heterostructures for Spintronics

ScienceCinema

Palmstrom, Chris [University of California, Santa Barbara, California, United States

2017-12-09

Electrical transport and spin-dependent transport across ferromagnet/semiconductor contacts is crucial in the realization of spintronic devices. Interfacial reactions, the formation of non-magnetic interlayers, and conductivity mismatch have been attributed to low spin injection efficiency. MBE has been used to grow epitaxial ferromagnetic metal/GA(1-x)AL(x)As heterostructures with the aim of controlling the interfacial structural, electronic, and magnetic properties. In situ, STM, XPS, RHEED and LEED, and ex situ XRD, RBS, TEM, magnetotransport, and magnetic characterization have been used to develop ferromagnetic elemental and metallic compound/compound semiconductor tunneling contacts for spin injection. The efficiency of the spin polarized current injected from the ferromagnetic contact has been determined by measuring the electroluminescence polarization of the light emitted from/GA(1-x)AL(x)As light-emitting diodes as a function of applied magnetic field and temperature. Interfacial reactions during MBE growth and post-growth anneal, as well as the semiconductor device band structure, were found to have a dramatic influence on the measured spin injection, including sign reversal. Lateral spin-transport devices with epitaxial ferromagnetic metal source and drain tunnel barrier contacts have been fabricated with the demonstration of electrical detection and the bias dependence of spin-polarized electron injection and accumulation at the contacts. This talk emphasizes the progress and achievements in the epitaxial growth of a number of ferromagnetic compounds/III-V semiconductor heterostructures and the progress towards spintronic devices.

Infrared nanoantenna apparatus and method for the manufacture thereof

DOEpatents

Peters, David W.; Davids, Paul; Leonhardt, Darin; Kim, Jin K.; Wendt, Joel R.; Klem, John F.

2014-06-10

An exemplary embodiment of the present invention is a photodetector comprising a semiconductor body, a periodically patterned metal nanoantenna disposed on a surface of the semiconductor body, and at least one electrode separate from the nanoantenna. The semiconductor body comprises an active layer in sufficient proximity to the nanoantenna for plasmonic coupling thereto. The nanoantenna is dimensioned to absorb electromagnetic radiation in at least some wavelengths not more than 12 .mu.m that are effective for plasmonic coupling into the active layer. The electrode is part of an electrode arrangement for obtaining a photovoltage or photocurrent in operation under appropriate stimulation.

Zone leveling and solution growth of complex compound semiconductors in space

NASA Technical Reports Server (NTRS)

Bachmann, K. J.

1986-01-01

A research program on complex semiconducting compounds and alloys was completed that addressed the growth of single crystals of CdSe(y)Te(1-y), Zn(x)Cd(1-x)Te, Mn(x)Cd(1-x)Te, InP(y)As(1-y) and CuInSe2 and the measurement of fundamental physico-chemical properties characterizing the above materials. The purpose of this ground based research program was to lay the foundations for further research concerning the growth of complex ternary compound semiconductors in a microgravity environment.

Plasma Reflection in Multigrain Layers of Narrow-Bandgap Semiconductors

NASA Astrophysics Data System (ADS)

Zhukov, N. D.; Shishkin, M. I.; Rokakh, A. G.

2018-04-01

Qualitatively similar spectral characteristics of plasma-resonance reflection in the region of 15-25 μm were obtained for layers of electrodeposited submicron particles of InSb, InAs, and GaAs and plates of these semiconductors ground with M1-grade diamond powder. The most narrow-bandgap semiconductor InSb (intrinsic absorption edge ˜7 μm) is characterized by an absorption band at 2.1-2.3 μm, which is interpreted in terms of the model of optical excitation of electrons coupled by the Coulomb interaction. The spectra of a multigrain layer of chemically deposited PbS nanoparticles (50-70 nm) exhibited absorption maxima at 7, 10, and 17 μm, which can be explained by electron transitions obeying the energy-quantization rules for quantum dots.

Metal-Insulator-Semiconductor Diode Consisting of Two-Dimensional Nanomaterials.

PubMed

Jeong, Hyun; Oh, Hye Min; Bang, Seungho; Jeong, Hyeon Jun; An, Sung-Jin; Han, Gang Hee; Kim, Hyun; Yun, Seok Joon; Kim, Ki Kang; Park, Jin Cheol; Lee, Young Hee; Lerondel, Gilles; Jeong, Mun Seok

2016-03-09

We present a novel metal-insulator-semiconductor (MIS) diode consisting of graphene, hexagonal BN, and monolayer MoS2 for application in ultrathin nanoelectronics. The MIS heterojunction structure was fabricated by vertically stacking layered materials using a simple wet chemical transfer method. The stacking of each layer was confirmed by confocal scanning Raman spectroscopy and device performance was evaluated using current versus voltage (I-V) and photocurrent measurements. We clearly observed better current rectification and much higher current flow in the MIS diode than in the p-n junction and the metal-semiconductor diodes made of layered materials. The I-V characteristic curve of the MIS diode indicates that current flows mainly across interfaces as a result of carrier tunneling. Moreover, we observed considerably high photocurrent from the MIS diode under visible light illumination.

Semiconductor laser devices having lateral refractive index tailoring

DOEpatents

Ashby, Carol I. H.; Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

1990-01-01

A broad-area semiconductor laser diode includes an active lasing region interposed between an upper and a lower cladding layer, the laser diode further comprising structure for controllably varying a lateral refractive index profile of the diode to substantially compensate for an effect of junction heating during operation. In embodiments disclosed the controlling structure comprises resistive heating strips or non-radiative linear junctions disposed parallel to the active region. Another embodiment discloses a multi-layered upper cladding region selectively disordered by implanted or diffused dopant impurities. Still another embodiment discloses an upper cladding layer of variable thickness that is convex in shape and symmetrically disposed about a central axis of the active region. The teaching of the invention is also shown to be applicable to arrays of semiconductor laser diodes.

37 CFR 211.5 - Deposit of identifying material.

Code of Federal Regulations, 2011 CFR

2011-07-01

... fixed in the form of the semiconductor chip product in which it was first commercially exploited... photograph of each layer of the work fixed in a semiconductor chip product. The visually perceptible... complete form of the mask work as fixed in a semiconductor product. (ii) Where the mask work contribution...

Electrostatic modification of novel materials

NASA Astrophysics Data System (ADS)

Ahn, C. H.; Bhattacharya, A.; di Ventra, M.; Eckstein, J. N.; Frisbie, C. Daniel; Gershenson, M. E.; Goldman, A. M.; Inoue, I. H.; Mannhart, J.; Millis, Andrew J.; Morpurgo, Alberto F.; Natelson, Douglas; Triscone, Jean-Marc

2006-10-01

Application of the field-effect transistor principle to novel materials to achieve electrostatic doping is a relatively new research area. It may provide the opportunity to bring about modifications of the electronic and magnetic properties of materials through controlled and reversible changes of the carrier concentration without modifying the level of disorder, as occurs when chemical composition is altered. As well as providing a basis for new devices, electrostatic doping can in principle serve as a tool for studying quantum critical behavior, by permitting the ground state of a system to be tuned in a controlled fashion. In this paper progress in electrostatic doping of a number of materials systems is reviewed. These include structures containing complex oxides, such as cuprate superconductors and colossal magnetoresistive compounds, organic semiconductors, in the form of both single crystals and thin films, inorganic layered compounds, single molecules, and magnetic semiconductors. Recent progress in the field is discussed, including enabling experiments and technologies, open scientific issues and challenges, and future research opportunities. For many of the materials considered, some of the results can be anticipated by combining knowledge of macroscopic or bulk properties and the understanding of the field-effect configuration developed during the course of the evolution of conventional microelectronics. However, because electrostatic doping is an interfacial phenomenon, which is largely an unexplored field, real progress will depend on the development of a better understanding of lattice distortion and charge transfer at interfaces in these systems.

Improved Stability and Performance of Visible Photoelectrochemical Water Splitting on Solution-Processed Organic Semiconductor Thin Films by Ultrathin Metal Oxide Passivation

DOE PAGES

Wang, Lei; Yan, Danhua; Shaffer, David W.; ...

2017-12-27

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. In this study, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm 2 photocurrents atmore » the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm 2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.« less

Improved Stability and Performance of Visible Photoelectrochemical Water Splitting on Solution-Processed Organic Semiconductor Thin Films by Ultrathin Metal Oxide Passivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lei; Yan, Danhua; Shaffer, David W.

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. In this study, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm 2 photocurrents atmore » the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm 2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.« less

Field-effect transistor having a superlattice channel and high carrier velocities at high applied fields

DOEpatents

Chaffin, R.J.; Dawson, L.R.; Fritz, I.J.; Osbourn, G.C.; Zipperian, T.E.

1987-06-08

A field effect transistor comprises a semiconductor having a source, a drain, a channel and a gate in operational relationship. The semiconductor is a strained layer superlattice comprising alternating quantum well and barrier layers, the quantum well layers and barrier layers being selected from the group of layer pairs consisting of InGaAs/AlGaAs, InAs/InAlGaAs, and InAs/InAlAsP. The layer thicknesses of the quantum well and barrier layers are sufficiently thin that the alternating layers constitute a superlattice which has a superlattice conduction band energy level structure in k-vector space. The layer thicknesses of the quantum well layers are selected to provide a superlattice L/sub 2D/-valley which has a shape which is substantially more two-dimensional than that of said bulk L-valley. 2 figs.

Fabrication of semiconductor-polymer compound nonlinear photonic crystal slab with highly uniform infiltration based on nano-imprint lithography technique.

PubMed

Qin, Fei; Meng, Zi-Ming; Zhong, Xiao-Lan; Liu, Ye; Li, Zhi-Yuan

2012-06-04

We present a versatile technique based on nano-imprint lithography to fabricate high-quality semiconductor-polymer compound nonlinear photonic crystal (NPC) slabs. The approach allows one to infiltrate uniformly polystyrene materials that possess large Kerr nonlinearity and ultrafast nonlinear response into the cylindrical air holes with diameter of hundred nanometers that are perforated in silicon membranes. Both the structural characterization via the cross-sectional scanning electron microscopy images and the optical characterization via the transmission spectrum measurement undoubtedly show that the fabricated compound NPC samples have uniform and dense polymer infiltration and are of high quality in optical properties. The compound NPC samples exhibit sharp transmission band edges and nondegraded high quality factor of microcavities compared with those in the bare silicon PC. The versatile method can be expanded to make general semiconductor-polymer hybrid optical nanostructures, and thus it may pave the way for reliable and efficient fabrication of ultrafast and ultralow power all-optical tunable integrated photonic devices and circuits.

Entropy-driven loss of gas-phase Group 5 species from GOLD/3-5 compound semiconductor systems

NASA Astrophysics Data System (ADS)

Pugh, J. H.; Williams, R. S.

1986-02-01

Temperature dependent chemical interactions between Au and nine 3-5 compound semiconductors (3=A1, Ga, In and V=P, As, Sb) have been calculated using bulk thermodynamic properties. Enthalpic considerations alone are insufficient to predict metal/compound-semiconductor reactivities. The entropy of vaporization of the group 5 elements is shown to be an extremely important driving force for chemical reactions involving the 3-5's, since it enables several endothermic reactions to occur spontaneously under certain temperature and pressure conditions. Plots of either Gibb's free energies of reaction or equilibrium vapor pressure of the group 5 element versus temperature are used to predict critical reaction temperatures for each of the systems studied. These plots agree extremely well with previous experimental observations of thin film reactions of Au on GaAs.

Lattice thermal expansion for normal tetrahedral compound semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omar, M.S.

2007-02-15

The cubic root of the deviation of the lattice thermal expansion from that of the expected value of diamond for group IV semiconductors, binary compounds of III-V and II-VI, as well as several ternary compounds from groups I-III-VI{sub 2}, II-IV-V{sub 2} and I-IV{sub 2}V{sub 3} semiconductors versus their bonding length are given straight lines. Their slopes were found to be 0.0256, 0.0210, 0.0170, 0.0259, 0.0196, and 0.02840 for the groups above, respectively. Depending on the valence electrons of the elements forming these groups, a formula was found to correlate all the values of the slopes mentioned above to that ofmore » group IV. This new formula which depends on the melting point and the bonding length as well as the number of valence electrons for the elements forming the compounds, will gives best calculated values for lattice thermal expansion for all compounds forming the groups mentioned above. An empirical relation is also found between the mean ionicity of the compounds forming the groups and their slopes mentioned above and that gave the mean ionicity for the compound CuGe{sub 2}P{sub 3} in the range of 0.442.« less

Influence of the Compositional Grading on Concentration of Majority Charge Carriers in Near-Surface Layers of n(p)-HgCdTe Grown by Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.

2018-02-01

The capacitive characteristics of metal-insulator-semiconductor (MIS) structures based on the compositionally graded Hg1-xCdxTe created by molecular beam epitaxy have been experimentally investigated in a wide temperature range (8-77 K). A program has been developed for numerical simulation of ideal capacitance-voltage (C-V) characteristics in the low-frequency and high-frequency approximations. The concentrations of the majority carriers in the near-surface semiconductor layer are determined from the values of the capacitances in the minima of low-frequency C-V curves. For MIS structures based on p-Hg1-xCdxTe, the effect of the presence of the compositionally graded layer on the hole concentration in the near-surface semiconductor layer, determined from capacitive measurements, has not been established. Perhaps this is due to the fact that the concentration of holes in the near-surface layer largely depends on the type of dielectric coating and the regimes of its application. For MIS structures based on n-Hg1-x Cd x Te (x = 0.22-0.23) without a graded-gap layer, the electron concentration determined by the proposed method is close to the average concentration determined by the Hall measurements. The electron concentration in the near-surface semiconductor layer of the compositionally graded n-Hg1-x Cd x Te (x = 0.22-0.23) found from the minimum capacitance value is much higher than the average electron concentration determined by the Hall measurements. The results are qualitatively explained by the creation of additional intrinsic donor-type defects in the near-surface compositionally graded layer of n-Hg1-x Cd x Te.

Epitaxial Growth of Cubic Crystalline Semiconductor Alloys on Basal Plane of Trigonal or Hexagonal Crystal

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor)

2011-01-01

Hetero-epitaxial semiconductor materials comprising cubic crystalline semiconductor alloys grown on the basal plane of trigonal and hexagonal substrates, in which misfit dislocations are reduced by approximate lattice matching of the cubic crystal structure to underlying trigonal or hexagonal substrate structure, enabling the development of alloyed semiconductor layers of greater thickness, resulting in a new class of semiconductor materials and corresponding devices, including improved hetero-bipolar and high-electron mobility transistors, and high-mobility thermoelectric devices.

Investigating compositional effects of atomic layer deposition ternary dielectric Ti-Al-O on metal-insulator-semiconductor heterojunction capacitor structure for gate insulation of InAlN/GaN and AlGaN/GaN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colon, Albert; Stan, Liliana; Divan, Ralu

Gate insulation/surface passivation in AlGaN/GaN and InAlN/GaN heterojunction field-effect transistors is a major concern for passivation of surface traps and reduction of gate leakage current. However, finding the most appropriate gate dielectric materials is challenging and often involves a compromise of the required properties such as dielectric constant, conduction/valence band-offsets, or thermal stability. Creating a ternary compound such as Ti-Al-O and tailoring its composition may result in a reasonably good gate material in terms of the said properties. To date, there is limited knowledge of the performance of ternary dielectric compounds on AlGaN/GaN and even less on InAlN/GaN. To approachmore » this problem, the authors fabricated metal-insulator-semiconductor heterojunction (MISH) capacitors with ternary dielectrics Ti-Al-O of various compositions, deposited by atomic layer deposition (ALD). The film deposition was achieved by alternating cycles of TiO2 and Al2O3 using different ratios of ALD cycles. TiO2 was also deposited as a reference sample. The electrical characterization of the MISH capacitors shows an overall better performance of ternary compounds compared to the pure TiO2. The gate leakage current density decreases with increasing Al content, being similar to 2-3 orders of magnitude lower for a TiO2:Al2O3 cycle ratio of 2:1. Although the dielectric constant has the highest value of 79 for TiO2 and decreases with increasing the number of Al2O3 cycles, it is maintaining a relatively high value compared to an Al2O3 film. Capacitance voltage sweeps were also measured in order to characterize the interface trap density. A decreasing trend in the interface trap density was found while increasing Al content in the film. In conclusion, our study reveals that the desired high-kappa properties of TiO2 can be adequately maintained while improving other insulator performance factors. The ternary compounds may be an excellent choice as a gate material for both AlGaN/GaN and InAlN/GaN based devices.« less

Planar varactor frequency multiplier devices with blocking barrier

NASA Technical Reports Server (NTRS)

Lieneweg, Udo (Inventor); Frerking, Margaret A. (Inventor); Maserjian, Joseph (Inventor)

1994-01-01

The invention relates to planar varactor frequency multiplier devices with a heterojunction blocking barrier for near millimeter wave radiation of moderate power from a fundamental input wave. The space charge limitation of the submillimeter frequency multiplier devices of the BIN(sup +) type is overcome by a diode structure comprising an n(sup +) doped layer of semiconductor material functioning as a low resistance back contact, a layer of semiconductor material with n-type doping functioning as a drift region grown on the back contact layer, a delta doping sheet forming a positive charge at the interface of the drift region layer with a barrier layer, and a surface metal contact. The layers thus formed on an n(sup +) doped layer may be divided into two isolated back-to-back BNN(sup +) diodes by separately depositing two surface metal contacts. By repeating the sequence of the drift region layer and the barrier layer with the delta doping sheet at the interfaces between the drift and barrier layers, a plurality of stacked diodes is formed. The novelty of the invention resides in providing n-type semiconductor material for the drift region in a GaAs/AlGaAs structure, and in stacking a plurality of such BNN(sup +) diodes stacked for greater output power with and connected back-to-back with the n(sup +) GaAs layer as an internal back contact and separate metal contact over an AlGaAs barrier layer on top of each stack.

Measurement of toxic volatile organic compounds in indoor air of semiconductor foundries using multisorbent adsorption/thermal desorption coupled with gas chromatography-mass spectrometry.

PubMed

Wu, Chien-Hou; Lin, Ming-Nan; Feng, Chien-Tai; Yang, Kuang-Ling; Lo, Yu-Shiu; Lo, Jiunn-Guang

2003-05-09

A method for the qualitative and quantitative analysis of volatile organic compounds (VOCs) in the air of class-100 clean rooms at semiconductor fabrication facilities was developed. Air samples from two semiconductor factories were collected each hour on multisorbent tubes (including Carbopack B, Carbopack C, and Carbosieve SIII) with a 24-h automatic active sampling system and analyzed using adsorption/thermal desorption coupled with gas chromatography-mass spectrometry. Experimental parameters, including thermal desorption temperature, desorption time, and cryofocusing temperature, were optimized. The average recoveries and the method detection limits for the target compounds were in the range 94-101% and 0.31-0.89 ppb, respectively, under the conditions of a 1 L sampling volume and 80% relative humidity. VOCs such as acetone, isopropyl alcohol, 2-heptanone, and toluene, which are commonly used in the semiconductor and electronics industries, were detected and accurately quantified with the established method. Temporal variations of the analyte concentrations observed were attributed to the improper use of organic solvents during operation.

Fast optical detecting media based on semiconductor nanostructures for recording images obtained using charges of free photocarriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasherininov, P. G., E-mail: peter.kasherininov@mail.ioffe.ru; Tomasov, A. A.; Beregulin, E. V.

2011-01-15

Available published data on the properties of optical recording media based on semiconductor structures are reviewed. The principles of operation, structure, parameters, and the range of application for optical recording media based on MIS structures formed of photorefractive crystals with a thick layer of insulator and MIS structures with a liquid crystal as the insulator (the MIS LC modulators), as well as the effect of optical bistability in semiconductor structures (semiconductor MIS structures with nanodimensionally thin insulator (TI) layer, M(TI)S nanostructures). Special attention is paid to recording media based on the M(TI)S nanostructures promising for fast processing of highly informativemore » images and to fabrication of optoelectronic correlators of images for noncoherent light.« less

Deposition method for producing silicon carbide high-temperature semiconductors

DOEpatents

Hsu, George C.; Rohatgi, Naresh K.

1987-01-01

An improved deposition method for producing silicon carbide high-temperature semiconductor material comprising placing a semiconductor substrate composed of silicon carbide in a fluidized bed silicon carbide deposition reactor, fluidizing the bed particles by hydrogen gas in a mildly bubbling mode through a gas distributor and heating the substrate at temperatures around 1200.degree.-1500.degree. C. thereby depositing a layer of silicon carbide on the semiconductor substrate.

Early Stages of Interface Formation at Compound Semiconductor Surfaces Studied by Scanning Tunneling Microscopy

DTIC Science & Technology

1991-10-01

classical image potential in an ideal creasing gap separation, that is specific to the form of the metal- insulator -semiconductor (MIS) junction...with which one can precisely adjust s, and hence continuously vary the vacvuum barrier, is a potentially valuable tool for investigating this effect- By... insulator -semiconductor (MIS) junction similar to that shown in Fig. I diverge at the semiconductor-vacuum and vacuum-metal interfaces [7,81. These

New materials and structures for photovoltaics

NASA Astrophysics Data System (ADS)

Zunger, Alex; Wagner, S.; Petroff, P. M.

1993-01-01

Despite the fact that over the years crystal chemists have discovered numerous semiconducting substances, and that modern epitaxial growth techniques are able to produce many novel atomic-scale architectures, current electronic and opto-electronic technologies are based but on a handful of ˜10 traditional semiconductor core materials. This paper surveys a number of yet-unexploited classes of semiconductors, pointing to the much-needed research in screening, growing, and characterizing promising members of these classes. In light of the unmanageably large number of a-priori possibilities, we emphasize the role that structural chemistry and modern computer-aided design must play in screening potentially important candidates. The basic classes of materials discussed here include nontraditional alloys, such as non-isovalent and heterostructural semiconductors, materials at reduced dimensionality, including superlattices, zeolite-caged nanostructures and organic semiconductors, spontaneously ordered alloys, interstitial semiconductors, filled tetrahedral structures, ordered vacancy compounds, and compounds based on d and f electron elements. A collaborative effort among material predictor, material grower, and material characterizer holds the promise for a successful identification of new and exciting systems.

Induced Charge Fluctuations in Semiconductor Detectors with a Cylindrical Geometry

NASA Astrophysics Data System (ADS)

Samedov, Victor V.

2018-01-01

Now, compound semiconductors are very appealing for hard X-ray room-temperature detectors for medical and astrophysical applications. Despite the attractive properties of compound semiconductors, such as high atomic number, high density, wide band gap, low chemical reactivity and long-term stability, poor hole and electron mobility-lifetime products degrade the energy resolution of these detectors. The main objective of the present study is in development of a mathematical model of the process of the charge induction in a cylindrical geometry with accounting for the charge carrier trapping. The formulae for the moments of the distribution function of the induced charge and the formulae for the mean amplitude and the variance of the signal at the output of the semiconductor detector with a cylindrical geometry were derived. It was shown that the power series expansions of the detector amplitude and the variance in terms of the inverse bias voltage allow determining the Fano factor, electron mobility lifetime product, and the nonuniformity level of the trap density of the semiconductor material.

Layered semiconductor neutron detectors

DOEpatents

Mao, Samuel S; Perry, Dale L

2013-12-10

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Tuning the Performance of Organic Spintronic Devices Using X-Ray Generated Traps

DTIC Science & Technology

2012-08-16

observed in organic devices using the same organic semiconductor, namely tris(8-hydroxyquinoli- nato)aluminium ( Alq3 ) [5,15]. Here we will show that the...manufacturing steps were carried out in a deposition chamber located inside a nitrogen glovebox. Next, the organic layer Alq3 (70 to 100 nm) followed by the...As the organic semiconductor spacer layer, the Alq3 layer was fabricated by thermal evaporation in a vacuum of 10Ś mbar at a rate of 0:1 nm=s. The Fe

Semiconductor laser having a non-absorbing passive region with beam guiding

NASA Technical Reports Server (NTRS)

Botez, Dan (Inventor)

1986-01-01

A laser comprises a semiconductor body having a pair of end faces and including an active region comprising adjacent active and guide layers which is spaced a distance from the end face and a passive region comprising adjacent non-absorbing guide and mode control layers which extends between the active region and the end face. The combination of the guide and mode control layers provides a weak positive index waveguide in the lateral direction thereby providing lateral mode control in the passive region between the active region and the end face.

Low-voltage organic electronics based on a gate-tunable injection barrier in vertical graphene-organic semiconductor heterostructures.

PubMed

Hlaing, Htay; Kim, Chang-Hyun; Carta, Fabio; Nam, Chang-Yong; Barton, Rob A; Petrone, Nicholas; Hone, James; Kymissis, Ioannis

2015-01-14

The vertical integration of graphene with inorganic semiconductors, oxide semiconductors, and newly emerging layered materials has recently been demonstrated as a promising route toward novel electronic and optoelectronic devices. Here, we report organic thin film transistors based on vertical heterojunctions of graphene and organic semiconductors. In these thin heterostructure devices, current modulation is accomplished by tuning of the injection barriers at the semiconductor/graphene interface with the application of a gate voltage. N-channel devices fabricated with a thin layer of C60 show a room temperature on/off ratio >10(4) and current density of up to 44 mAcm(-2). Because of the ultrashort channel intrinsic to the vertical structure, the device is fully operational at a driving voltage of 200 mV. A complementary p-channel device is also investigated, and a logic inverter based on two complementary transistors is demonstrated. The vertical integration of graphene with organic semiconductors via simple, scalable, and low-temperature fabrication processes opens up new opportunities to realize flexible, transparent organic electronic, and optoelectronic devices.

Time-Resolved Photoluminescence Microscopy for the Analysis of Semiconductor-Based Paint Layers

PubMed Central

Mosca, Sara; Gonzalez, Victor; Eveno, Myriam

2017-01-01

In conservation, science semiconductors occur as the constituent matter of the so-called semiconductor pigments, produced following the Industrial Revolution and extensively used by modern painters. With recent research highlighting the occurrence of various degradation phenomena in semiconductor paints, it is clear that their detection by conventional optical fluorescence imaging and microscopy is limited by the complexity of historical painting materials. Here, we illustrate and prove the capabilities of time-resolved photoluminescence (TRPL) microscopy, equipped with both spectral and lifetime sensitivity at timescales ranging from nanoseconds to hundreds of microseconds, for the analysis of cross-sections of paint layers made of luminescent semiconductor pigments. The method is sensitive to heterogeneities within micro-samples and provides valuable information for the interpretation of the nature of the emissions in samples. A case study is presented on micro samples from a painting by Henri Matisse and serves to demonstrate how TRPL can be used to identify the semiconductor pigments zinc white and cadmium yellow, and to inform future investigations of the degradation of a cadmium yellow paint. PMID:29160862

Wholly Aromatic Ether-Imides as n-Type Semiconductors

NASA Technical Reports Server (NTRS)

Weiser, Erik; St. Clair, Terry L.; Dingemans, Theo J.; Samulski, Edward T.; Irene, Gene

2006-01-01

Some wholly aromatic ether-imides consisting of rod-shaped, relatively-low-mass molecules that can form liquid crystals have been investigated for potential utility as electron-donor-type (ntype) organic semiconductors. It is envisioned that after further research to improve understanding of their physical and chemical properties, compounds of this type would be used to make thin film semiconductor devices (e.g., photovoltaic cells and field-effect transistors) on flexible electronic-circuit substrates. This investigation was inspired by several prior developments: Poly(ether-imides) [PEIs] are a class of engineering plastics that have been used extensively in the form of films in a variety of electronic applications, including insulating layers, circuit boards, and low-permittivity coatings. Wholly aromatic PEIs containing naphthalene and perylene moieties have been shown to be useful as electrochromic polymers. More recently, low-molecular-weight imides comprising naphthalene-based molecules with terminal fluorinated tails were shown to be useful as n-type organic semiconductors in such devices as field-effect transistors and Schottky diodes. Poly(etherimide)s as structural resins have been extensively investigated at NASA Langley Research Center for over 30 years. More recently, the need for multi-functional materials has become increasingly important. This n-type semiconductor illustrates the scope of current work towards new families of PEIs that not only can be used as structural resins for carbon-fiber reinforced composites, but also can function as sensors. Such a multi-functional material would permit so-called in-situ health monitoring of composite structures during service. The work presented here demonstrates that parts of the PEI backbone can be used as an n-type semiconductor with such materials being sensitive to damage, temperature, stress, and pressure. In the near future, multi-functional or "smart" composite structures are envisioned to be able to communicate such important parameters to the flight crew and provide vital information with respect to the operational status of their aircraft.

Hybrid anode for semiconductor radiation detectors

DOEpatents

Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

2013-11-19

The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

Sustained hole inversion layer in a wide-bandgap metal-oxide semiconductor with enhanced tunnel current

NASA Astrophysics Data System (ADS)

Shoute, Gem; Afshar, Amir; Muneshwar, Triratna; Cadien, Kenneth; Barlage, Douglas

2016-02-01

Wide-bandgap, metal-oxide thin-film transistors have been limited to low-power, n-type electronic applications because of the unipolar nature of these devices. Variations from the n-type field-effect transistor architecture have not been widely investigated as a result of the lack of available p-type wide-bandgap inorganic semiconductors. Here, we present a wide-bandgap metal-oxide n-type semiconductor that is able to sustain a strong p-type inversion layer using a high-dielectric-constant barrier dielectric when sourced with a heterogeneous p-type material. A demonstration of the utility of the inversion layer was also investigated and utilized as the controlling element in a unique tunnelling junction transistor. The resulting electrical performance of this prototype device exhibited among the highest reported current, power and transconductance densities. Further utilization of the p-type inversion layer is critical to unlocking the previously unexplored capability of metal-oxide thin-film transistors, such applications with next-generation display switches, sensors, radio frequency circuits and power converters.

Semiconductor cylinder fiber laser

NASA Astrophysics Data System (ADS)

Sandupatla, Abhinay; Flattery, James; Kornreich, Philipp

2015-12-01

We fabricated a fiber laser that uses a thin semiconductor layer surrounding the glass core as the gain medium. This is a completely new type of laser. The In2Te3 semiconductor layer is about 15-nm thick. The fiber laser has a core diameter of 14.2 μm, an outside diameter of 126 μm, and it is 25-mm long. The laser mirrors consist of a thick vacuum-deposited aluminum layer at one end and a thin semitransparent aluminum layer deposited at the other end of the fiber. The laser is pumped from the side with either light from a halogen tungsten incandescent lamp or a blue light emitting diode flash light. Both the In2Te3 gain medium and the aluminum mirrors have a wide bandwidth. Therefore, the output spectrum consists of a pedestal from a wavelength of about 454 to 623 nm with several peaks. There is a main peak at 545 nm. The main peak has an amplitude of 16.5 dB above the noise level of -73 dB.

High-Performance Nonvolatile Organic Field-Effect Transistor Memory Based on Organic Semiconductor Heterostructures of Pentacene/P13/Pentacene as Both Charge Transport and Trapping Layers.

PubMed

Li, Wen; Guo, Fengning; Ling, Haifeng; Zhang, Peng; Yi, Mingdong; Wang, Laiyuan; Wu, Dequn; Xie, Linghai; Huang, Wei

2017-08-01

Nonvolatile organic field-effect transistor (OFET) memory devices based on pentacene/ N , N '-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (P13)/pentacene trilayer organic heterostructures have been proposed. The discontinuous n-type P13 embedded in p-type pentacene layers can not only provide electrons in the semiconductor layer that facilitates electron trapping process; it also works as charge trapping sites, which is attributed to the quantum well-like pentacene/P13/pentacene organic heterostructures. The synergistic effects of charge trapping in the discontinuous P13 and the charge-trapping property of the poly(4-vinylphenol) (PVP) layer remarkably improve the memory performance. In addition, the trilayer organic heterostructures have also been successfully applied to multilevel and flexible nonvolatile memory devices. The results provide a novel design strategy to achieve high-performance nonvolatile OFET memory devices and allow potential applications for different combinations of various organic semiconductor materials in OFET memory.

High‐Performance Nonvolatile Organic Field‐Effect Transistor Memory Based on Organic Semiconductor Heterostructures of Pentacene/P13/Pentacene as Both Charge Transport and Trapping Layers

PubMed Central

Li, Wen; Guo, Fengning; Ling, Haifeng; Zhang, Peng; Wang, Laiyuan; Wu, Dequn

2017-01-01

Nonvolatile organic field‐effect transistor (OFET) memory devices based on pentacene/N,N′‐ditridecylperylene‐3,4,9,10‐tetracarboxylic diimide (P13)/pentacene trilayer organic heterostructures have been proposed. The discontinuous n‐type P13 embedded in p‐type pentacene layers can not only provide electrons in the semiconductor layer that facilitates electron trapping process; it also works as charge trapping sites, which is attributed to the quantum well‐like pentacene/P13/pentacene organic heterostructures. The synergistic effects of charge trapping in the discontinuous P13 and the charge‐trapping property of the poly(4‐vinylphenol) (PVP) layer remarkably improve the memory performance. In addition, the trilayer organic heterostructures have also been successfully applied to multilevel and flexible nonvolatile memory devices. The results provide a novel design strategy to achieve high‐performance nonvolatile OFET memory devices and allow potential applications for different combinations of various organic semiconductor materials in OFET memory. PMID:28852619

Apparatus and methods for memory using in-plane polarization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Junwei; Chang, Kai; Ji, Shuai-Hua

A memory device includes a semiconductor layer with an in-plane polarization component switchable between a first direction and a second direction. A writing electrode is employed to apply a writing voltage to the semiconductor layer to change the in-plane polarization component between the first direction and the second direction. A reading electrode is employed to apply a reading voltage to the semiconductor layer to measure a tunneling current substantially perpendicular to the polarization direction of the in-plane polarization component. The directions of the reading voltage and the writing voltage are substantially perpendicular to each other. Therefore, the reading process ismore » non-destructive. Thin films (e.g., one unit cell thick) of ferroelectric material can be used in the memory device to increase the miniaturization of the device.« less

Metal-oxide-semiconductor devices using Ga2O3 dielectrics on n-type GaN

NASA Astrophysics Data System (ADS)

Lee, Ching-Ting; Chen, Hong-Wei; Lee, Hsin-Ying

2003-06-01

Using a photoelectrochemical method involving a He-Cd laser, Ga2O3 oxide layers were directly grown on n-type GaN. We demonstrated the performance of the resultant metal-oxide-semiconductor devices based on the grown Ga2O3 layer. An extremely low reverse leakage current of 200 pA was achieved when devices operated at -20 V. Furthermore, high forward and reverse breakdown electric fields of 2.80 MV/cm and 5.70 MV/cm, respectively, were obtained. Using a photoassisted current-voltage method, a low interface state density of 2.53×1011 cm-2 eV-1 was estimated. The varactor devices permit formation of inversion layers, so that they may be applied for the fabrication of metal-oxide-semiconductor field-effect transistors.

Ultrafast and Ultrasensitive Gas Sensors Derived from a Large Fermi-Level Shift in the Schottky Junction with Sieve-Layer Modulation.

PubMed

Cheng, Ching-Cheng; Wu, Chia-Lin; Liao, Yu-Ming; Chen, Yang-Fang

2016-07-13

Gas sensors play an important role in numerous fields, covering a wide range of applications, including intelligent systems and detection of harmful and toxic gases. Even though they have attracted much attention, the response time on the order of seconds to minutes is still very slow. To circumvent the existing problems, here, we provide a seminal attempt with the integration of graphene, semiconductor, and an addition sieve layer forming a nanocomposite gas sensor with ultrahigh sensitivity and ultrafast response. The designed sieve layer has a suitable band structure that can serve as a blocking layer to prevent transfer of the charges induced by adsorbed gas molecules into the underlying semiconductor layer. We found that the sensitivity can be reduced to the parts per million level, and the ultrafast response of around 60 ms is unprecedented compared with published graphene-based gas sensors. The achieved high performance can be interpreted well by the large change of the Fermi level of graphene due to its inherent nature of the low density of states and blocking of the sieve layer to prevent charge transfer from graphene to the underlying semiconductor layer. Accordingly, our work is very useful and timely for the development of gas sensors with high performance for practical applications.

Optical fiber sensors based on nanostructured coatings fabricated by means of the layer-by-layer electrostatic self-assembly method

NASA Astrophysics Data System (ADS)

Arregui, Francisco J.; Matías, Ignacio R.; Claus, Richard O.

2007-07-01

The Layer-by-Layer Electrostatic Self-Assembly (ESA) method has been successfully used for the design and fabrication of nanostructured materials. More specifically, this technique has been applied for the deposition of thin films on optical fibers with the purpose of fabricating different types of optical fiber sensors. In fact, optical fiber sensors for measuring humidity, temperature, pH, hydrogen peroxide, glucose, volatile organic compounds or even gluten have been already experimentally demonstrated. The versatility of this technique allows the deposition of these sensing coatings on flat substrates and complex geometries as well. For instance, nanoFabry-Perots and microgratings have been formed on cleaved ends of optical fibers (flat surfaces) and also sensing coatings have been built onto long period gratings (cylindrical shape), tapered fiber ends (conical shape), biconically tapered fibers or even the internal side of hollow core fibers. Among the different materials used for the construction of these sensing nanostructured coatings, diverse types such as polymers, inorganic semiconductors, colorimetric indicators, fluorescent dyes, quantum dots or even biological elements as enzymes can be found. This technique opens the door to the fabrication of new types of optical fiber sensors.

Compound semiconductor optical waveguide switch

DOEpatents

Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

2003-06-10

An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

Method of plasma etching Ga-based compound semiconductors

DOEpatents

Qiu, Weibin; Goddard, Lynford L.

2012-12-25

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

Method of plasma etching GA-based compound semiconductors

DOEpatents

Qiu, Weibin; Goddard, Lynford L.

2013-01-01

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

Nanoscale doping of compound semiconductors by solid phase dopant diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Jaehyun, E-mail: jaehyun.ahn@utexas.edu; Koh, Donghyi; Roy, Anupam

2016-03-21

Achieving damage-free, uniform, abrupt, ultra-shallow junctions while simultaneously controlling the doping concentration on the nanoscale is an ongoing challenge to the scaling down of electronic device dimensions. Here, we demonstrate a simple method of effectively doping ΙΙΙ-V compound semiconductors, specifically InGaAs, by a solid phase doping source. This method is based on the in-diffusion of oxygen and/or silicon from a deposited non-stoichiometric silicon dioxide (SiO{sub x}) film on InGaAs, which then acts as donors upon activation by annealing. The dopant profile and concentration can be controlled by the deposited film thickness and thermal annealing parameters, giving active carrier concentration ofmore » 1.4 × 10{sup 18 }cm{sup −3}. Our results also indicate that conventional silicon based processes must be carefully reviewed for compound semiconductor device fabrication to prevent unintended doping.« less

Method and apparatus for increasing the durability and yield of thin film photovoltaic devices

DOEpatents

Phillips, J.E.; Lasswell, P.G.

1987-02-03

Thin film photovoltaic cells having a pair of semiconductor layers between an opaque and a transparent electrical contact are manufactured in a method which includes the step of scanning one of the semiconductor layers to determine the location of any possible shorting defect. Upon the detection of such defect, the defect is eliminated to increase the durability and yield of the photovoltaic device. 10 figs.

Method and apparatus for increasing the durability and yield of thin film photovoltaic devices

DOEpatents

Phillips, James E.; Lasswell, Patrick G.

1987-01-01

Thin film photovoltaic cells having a pair of semiconductor layers between an opaque and a transparent electrical contact are manufactured in a method which includes the step of scanning one of the semiconductor layers to determine the location of any possible shorting defect. Upon the detection of such defect, the defect is eliminated to increase the durability and yield of the photovoltaic device.

Investigations on Substrate Temperature-Induced Growth Modes of Organic Semiconductors at Dielectric/semiconductor Interface and Their Correlation with Threshold Voltage Stability in Organic Field-Effect Transistors.

PubMed

Padma, Narayanan; Maheshwari, Priya; Bhattacharya, Debarati; Tokas, Raj B; Sen, Shashwati; Honda, Yoshihide; Basu, Saibal; Pujari, Pradeep Kumar; Rao, T V Chandrasekhar

2016-02-10

Influence of substrate temperature on growth modes of copper phthalocyanine (CuPc) thin films at the dielectric/semiconductor interface in organic field effect transistors (OFETs) is investigated. Atomic force microscopy (AFM) imaging at the interface reveals a change from 'layer+island' to "island" growth mode with increasing substrate temperatures, further confirmed by probing the buried interfaces using X-ray reflectivity (XRR) and positron annihilation spectroscopic (PAS) techniques. PAS depth profiling provides insight into the details of molecular ordering while positron lifetime measurements reveal the difference in packing modes of CuPc molecules at the interface. XRR measurements show systematic increase in interface width and electron density correlating well with the change from layer + island to coalesced huge 3D islands at higher substrate temperatures. Study demonstrates the usefulness of XRR and PAS techniques to study growth modes at buried interfaces and reveals the influence of growth modes of semiconductor at the interface on hole and electron trap concentrations individually, thereby affecting hysteresis and threshold voltage stability. Minimum hole trapping is correlated to near layer by layer formation close to the interface at 100 °C and maximum to the island formation with large voids between the grains at 225 °C.

Pump-probe surface photovoltage spectroscopy measurements on semiconductor epitaxial layers.

PubMed

Jana, Dipankar; Porwal, S; Sharma, T K; Kumar, Shailendra; Oak, S M

2014-04-01

Pump-probe Surface Photovoltage Spectroscopy (SPS) measurements are performed on semiconductor epitaxial layers. Here, an additional sub-bandgap cw pump laser beam is used in a conventional chopped light geometry SPS setup under the pump-probe configuration. The main role of pump laser beam is to saturate the sub-bandgap localized states whose contribution otherwise swamp the information related to the bandgap of material. It also affects the magnitude of Dember voltage in case of semi-insulating (SI) semiconductor substrates. Pump-probe SPS technique enables an accurate determination of the bandgap of semiconductor epitaxial layers even under the strong influence of localized sub-bandgap states. The pump beam is found to be very effective in suppressing the effect of surface/interface and bulk trap states. The overall magnitude of SPV signal is decided by the dependence of charge separation mechanisms on the intensity of the pump beam. On the contrary, an above bandgap cw pump laser can be used to distinguish the signatures of sub-bandgap states by suppressing the band edge related feature. Usefulness of the pump-probe SPS technique is established by unambiguously determining the bandgap of p-GaAs epitaxial layers grown on SI-GaAs substrates, SI-InP wafers, and p-GaN epilayers grown on Sapphire substrates.

The AMOS cell - An improved metal-semiconductor solar cell. [Antireflection coated Metal Oxide Semiconductor

NASA Technical Reports Server (NTRS)

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

1975-01-01

A new fabrication process is being developed which significantly improves the efficiency of metal-semiconductor solar cells. The resultant effect, a marked increase in the open-circuit voltage, is produced by the addition of an interfacial layer oxide on the semiconductor. Cells using gold on n-type gallium arsenide have been made in small areas (0.17 sq cm) with conversion efficiencies of 15% in terrestrial sunlight.

Materials Science and Device Physics of 2-Dimensional Semiconductors

NASA Astrophysics Data System (ADS)

Fang, Hui

Materials and device innovations are the keys to future technology revolution. For MOSFET scaling in particular, semiconductors with ultra-thin thickness on insulator platform is currently of great interest, due to the potential of integrating excellent channel materials with the industrially mature Si processing. Meanwhile, ultra-thin thickness also induces strong quantum confinement which in turn affect most of the material properties of these 2-dimensional (2-D) semiconductors, providing unprecedented opportunities for emerging technologies. In this thesis, multiple novel 2-D material systems are explored. Chapter one introduces the present challenges faced by MOSFET scaling. Chapter two covers the integration of ultrathin III V membranes with Si. Free standing ultrathin III-V is studied to enable high performance III-V on Si MOSFETs with strain engineering and alloying. Chapter three studies the light absorption in 2-D membranes. Experimental results and theoretical analysis reveal that light absorption in the 2-D quantum membranes is quantized into a fundamental physical constant, where we call it the quantum unit of light absorption, irrelevant of most of the material dependent parameters. Chapter four starts to focus on another 2-D system, atomic thin layered chalcogenides. Single and few layered chalcogenides are first explored as channel materials, with focuses in engineering the contacts for high performance MOSFETs. Contact treatment by molecular doping methods reveals that many layered chalcogenides other than MoS2 exhibit good transport properties at single layer limit. Finally, Chapter five investigated 2-D van der Waals heterostructures built from different single layer chalcogenides. The investigation in a WSe2/MoS2 hetero-bilayer shows a large Stokes like shift between photoluminescence peak and lowest absorption peak, as well as strong photoluminescence intensity, consistent with spatially indirect transition in a type II band alignment in this van der Waals heterostructure. This result enables new family of semiconductor heterostructures having tunable optoelectronic properties with customized composite layers and highlights the ability to build van der Waals semiconductor heterostructure lasers/LEDs.

Transparent Oxide Thin-Film Transistors: Production, Characterization and Integration

NASA Astrophysics Data System (ADS)

Barquinha, Pedro Miguel Candido

This dissertation is devoted to the study of the emerging area of transparent electronics, summarizing research work regarding the development of n-type thin-film transistors (TFTs) based on sputtered oxide semiconductors. All the materials are produced without intentional substrate heating, with annealing temperatures of only 150-200 °C being used to optimize transistor performance. The work is based on the study and optimization of active semiconductors from the gallium-indium-zinc oxide system, including both the binary compounds Ga2O3, In2O3 and ZnO, as well as ternary and quaternary oxides based on mixtures of those, such as IZO and GIZO with different atomic ratios. Several topics are explored, including the study and optimization of the oxide semiconductor thin films, their application as channel layers on TFTs and finally the implementation of the optimized processes to fabricate active matrix backplanes to be integrated in liquid crystal display (LCD) prototypes. Sputtered amorphous dielectrics with high dielectric constant (high-kappa) based on mixtures of tantalum-silicon or tantalum-aluminum oxides are also studied and used as the dielectric layers on fully transparent TFTs. These devices also include transparent and highly conducting IZO thin films as source, drain and gate electrodes. Given the flexibility of the sputtering technique, oxide semiconductors are analyzed regarding several deposition parameters, such as oxygen partial pressure and deposition pressure, as well as target composition. One of the most interesting features of multicomponent oxides such as IZO and GIZO is that, due to their unique electronic configuration and carrier transport mechanism, they allow to obtain amorphous structures with remarkable electrical properties, such as high hall-effect mobility that exceeds 60 cm2 V -1 s-1 for IZO. These properties can be easily tuned by changing the processing conditions and the atomic ratios of the multicomponent oxides, allowing to have amorphous oxides suitable to be used either as transparent semiconductors or as highly conducting electrodes. The amorphous structure, which is maintained even if the thin films are annealed at 500 °C, brings great advantages concerning interface quality and uniformity in large areas. A complete study comprising different deposition conditions of the semiconductor layer is also made regarding TFT electrical performance. Optimized devices present outstanding electrical performance, such as field-effect mobility (muFE) exceeding 20 cm2 V -1 s-1, turn-on voltage (Von) between -1 and 1 V, subthreshold slope (S) lower than 0.25 V dec-1 and On-Off ratio above 107 . Devices employing amorphous multicomponent oxides present largely improved properties when compared with the ones based on polycrystalline ZnO, mostly in terms of muFE. Within the compositional range where IZO and GIZO films are amorphous, TFT performance can be largely adjusted: for instance, high indium contents favor large mu FE but also highly negative Von, which can be compensated by proper amounts of zinc and gallium. Large oxygen concentrations during oxide semiconductor sputtering are found to be deleterious, decreasing muFE, shifting Von towards high values and turning the devices electrically unstable. It is also shown that semiconductor thickness (ds) has a very important role: for instance, by reducing ds to 10 nm it is possible to produce TFTs with Von≈0 V even using deposition conditions and/or target compositions that normally yield highly conducting films. Given the low ds of the films, this behavior is mostly related with surface states existent at the oxide semiconductor air-exposed back-surface, where depletion layers that can extend towards the dielectric/semiconductor interface are created due to the interaction with atmospheric oxygen. Different passivation layers on top of this air-exposed surface are studied, with SU-8 revealing to be to most effective one. Other important topics are source-drain contact resistance assessment and the effect of different annealing temperatures ( TA), being the properties of the TFTs dominated by TA rather than by the deposition conditions as TA increases. Fully transparent TFTs employing sputtered amorphous multicomponent dielectrics produced without intentional substrate heating present excellent electrical properties, that approach those exhibited by devices using PECVD SiO2 produced at 400 °C. Gate leakage current can be greatly reduced by using tantalum-silicon or tantalum-aluminum oxides rather than Ta2O5. A section of this dissertation is also devoted to the analysis of current stress stability and aging effects of the TFTs, being found that optimal devices exhibit recoverable threshold voltage shifts lower than 0.50 V after 24 h stress with constant drain current of 10 muA, as well as negligible aging effects during 18 months. The research work of this dissertation culminates in the fabrication of a backplane employing transparent TFTs and subsequent integration with a LCD frontplane by Hewlett-Packard. The successful operation of this initial 2.8h prototype with 128x128 pixels provides a solid demonstration that oxide semiconductor-based TFTs have the potential to largely contribute to a novel electronics era, where semiconductor materials away from conventional silicon are used to create fascinating applications, such as transparent electronic products.

Magnetism in Mn-nanowires and -clusters as δ-doped layers in group IV semiconductors (Si, Ge)

NASA Astrophysics Data System (ADS)

Simov, K. R.; Glans, P.-A.; Jenkins, C. A.; Liberati, M.; Reinke, P.

2018-01-01

Mn doping of group-IV semiconductors (Si/Ge) is achieved by embedding nanostructured Mn-layers in group-IV matrix. The Mn-nanostructures are monoatomic Mn-wires or Mn-clusters and capped with an amorphous Si or Ge layer. The precise fabrication of δ-doped Mn-layers is combined with element-specific detection of the magnetic signature with x-ray magnetic circular dichroism. The largest moment (2.5 μB/Mn) is measured for Mn-wires with ionic bonding character and a-Ge overlayer cap; a-Si capping reduces the moment due to variations of bonding in agreement with theoretical predictions. The moments in δ-doped layers dominated by clusters is quenched with an antiferromagnetic component from Mn-Mn bonding.

Ultra-thin ohmic contacts for p-type nitride light emitting devices

DOEpatents

Raffetto, Mark; Bharathan, Jayesh; Haberern, Kevin; Bergmann, Michael; Emerson, David; Ibbetson, James; Li, Ting

2014-06-24

A flip-chip semiconductor based Light Emitting Device (LED) can include an n-type semiconductor substrate and an n-type GaN epi-layer on the substrate. A p-type GaN epi-layer can be on the n-type GaN epi-layer and a metal ohmic contact p-electrode can be on the p-type GaN epi-layer, where the metal ohmic contact p-electrode can have an average thickness less than about 25 .ANG.. A reflector can be on the metal ohmic contact p-electrode and a metal stack can be on the reflector. An n-electrode can be on the substrate opposite the n-type GaN epi-layer and a bonding pad can be on the n-electrode.

Epitaxial growth of GaSb on V-grooved Si (001) substrates with an ultrathin GaAs stress relaxing layer

NASA Astrophysics Data System (ADS)

Li, Qiang; Lai, Billy; Lau, Kei May

2017-10-01

We report epitaxial growth of GaSb nano-ridge structures and planar thin films on V-groove patterned Si (001) substrates by leveraging the aspect ratio trapping technique. GaSb was deposited on {111} Si facets of the V-shaped trenches using metal-organic chemical vapor deposition with a 7 nm GaAs growth initiation layer. Transmission electron microscopy analysis reveals the critical role of the GaAs layer in providing a U-shaped surface for subsequent GaSb epitaxy. A network of misfit dislocations was uncovered at the GaSb/GaAs hetero-interface. We studied the evolution of the lattice relaxation as the growth progresses from closely pitched GaSb ridges to coalesced thin films using x-ray diffraction. The omega rocking curve full-width-at-half-maximum of the resultant GaSb thin film is among the lowest values reported by molecular beam epitaxy, substantiating the effectiveness of the defect necking mechanism. These results thus present promising opportunities for the heterogeneous integration of devices based on 6.1 Å family compound semiconductors.

Superconducting critical fields of alkali and alkaline-earth intercalates of MoS2

NASA Technical Reports Server (NTRS)

Woollam, J. A.; Somoano, R. B.

1976-01-01

Results are reported for measurements of the critical-field anisotropy and temperature dependence of group-VIB semiconductor MoS2 intercalated with the alkali and alkaline-earth metals Na, K, Rb, Cs, and Sr. The temperature dependences are compared with present theories on the relation between critical field and transition temperature in the clean and dirty limits over the reduced-temperature range from 1 to 0.1. The critical-field anisotropy data are compared with predictions based on coupled-layers and thin-film ('independent-layers') models. It is found that the critical-field boundaries are steep in all cases, that the fields are greater than theoretical predictions at low temperatures, and that an unusual positive curvature in the temperature dependence appears which may be related to the high anisotropy of the layer structure. The results show that materials with the largest ionic intercalate atom diameters and hexagonal structures (K, Rb, and Cs compounds) have the highest critical temperatures, critical fields, and critical-boundary slopes; the critical fields of these materials are observed to exceed the paramagnetic limiting fields.

Tube Formation in Nanoscale Materials

PubMed Central

2008-01-01

The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb2O5nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities. PMID:20592945

Single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides as promising photocatalysts.

PubMed

Bai, Yujie; Luo, Gaixia; Meng, Lijuan; Zhang, Qinfang; Xu, Ning; Zhang, Haiyang; Wu, Xiuqiang; Kong, Fanjie; Wang, Baolin

2018-05-30

Searching for two-dimensional semiconductor materials that are suitable for visible-light photocatalytic water splitting provides a sustainable solution to deal with the future energy crisis and environmental problems. Herein, based on first-principles calculations, single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides are proposed as efficient photocatalysts for water splitting. Stability analyses show that the single-layer ZnMN2 zinc nitrides exhibit energetic and dynamical stability. The electronic properties reveal that all of the single-layer ZnMN2 zinc nitrides are semiconductors. Interestingly, single-layer ZnSnN2 is a direct band gap semiconductor with a desirable band gap (1.74 eV), and the optical adsorption spectrum confirms its optical absorption in the visible light region. The hydrogen evolution reaction (HER) calculations show that the catalytic activity for single-layer ZnMN2 (M = Ge, Sn) is better than that of single-layer ZnSiN2. Furthermore, the band gaps and band edge positions for the single-layer ZnMN2 zinc nitrides can be effectively tuned by biaxial strain. Especially, single-layer ZnGeN2 can be effectively tuned to match better with the redox potentials of water and enhance the light absorption in the visible light region at a tensile strain of 5%, which is confirmed by the corresponding optical absorption spectrum. Our results provide guidance for experimental synthesis efforts and future searches for single-layer materials suitable for photocatalytic water splitting.

High resolution three-dimensional doping profiler

DOEpatents

Thundat, Thomas G.; Warmack, Robert J.

1999-01-01

A semiconductor doping profiler provides a Schottky contact at one surface and an ohmic contact at the other. While the two contacts are coupled to a power source, thereby establishing an electrical bias in the semiconductor, a localized light source illuminates the semiconductor to induce a photocurrent. The photocurrent changes in accordance with the doping characteristics of the semiconductor in the illuminated region. By changing the voltage of the power source the depth of the depletion layer can be varied to provide a three dimensional view of the local properties of the semiconductor.

Making Single-Source Precursors of Ternary Semiconductors

NASA Technical Reports Server (NTRS)

Hepp, Aloysius; Banger, Kulbindre K.

2007-01-01

A synthesis route has been developed for the commercial manufacture of single- source precursors of chalcopyrite semiconductor absorber layers of thin-film solar photovoltaic cells. A closely related class of single-source precursors of these semiconductors, and their synthesis routes, were reported in "Improved Single-Source Precursors for Solar-Cell Absorbers" (LEW-17445-1), NASA Tech Briefs, Vol. 31, No. 6 (June 2007), page 56. The present synthesis route is better suited to commercialization because it is simpler and involves the use of commercially available agents, yet offers the flexibility needed for synthesis of a variety of precursors. A single-source precursor of the type of interest here is denoted by the general formula L2M'(mu-ER)2M(ER)2, where L signifies a Lewis base; M signifies Al, In, or Ga; M' signifies Ag or Cu; R signifies an alkyl, aryl, silyl, or perfluorocarbon group; E signifies O, S, Se, or Te; and mu signifies a bridging ligand. This compound can be synthesized in a "one-pot" procedure from ingredients that are readily available from almost any chemical supplier. In a demonstration, the following synthesis was performed: Under anaerobic conditions, InCl3 was reacted with sodium ethanethiolate in methanol in a 1:4 molar ratio to afford the ionic stable intermediate compound Na+[In(SEt)4]- (where Et signifies ethyl group). After approximately 15 minutes, a heterogeneous solution of CuCl and the Lewis base PPh3 (where Ph signifies phenyl) in a 1:2 ratio in a mixture of CH3CN and CH2Cl2 was added directly to the freshly prepared Na+[In(SEt)4]-. After 24 hours, the reaction was essentially complete. The methanolic solution was concentrated, then the product was extracted with CH2Cl2, then the product was washed with dry ether and pentane. The product in its final form was a creamy white solid. Spectroscopic and elemental analysis confirmed that the product was (PPh3)2Cu(mu-SEt)2In(mu-SEt)2, which is known to be a precursor of the ternary semiconductor CuInS2.

Electric field induced spin-polarized current

DOEpatents

Murakami, Shuichi; Nagaosa, Naoto; Zhang, Shoucheng

2006-05-02

A device and a method for generating an electric-field-induced spin current are disclosed. A highly spin-polarized electric current is generated using a semiconductor structure and an applied electric field across the semiconductor structure. The semiconductor structure can be a hole-doped semiconductor having finite or zero bandgap or an undoped semiconductor of zero bandgap. In one embodiment, a device for injecting spin-polarized current into a current output terminal includes a semiconductor structure including first and second electrodes, along a first axis, receiving an applied electric field and a third electrode, along a direction perpendicular to the first axis, providing the spin-polarized current. The semiconductor structure includes a semiconductor material whose spin orbit coupling energy is greater than room temperature (300 Kelvin) times the Boltzmann constant. In one embodiment, the semiconductor structure is a hole-doped semiconductor structure, such as a p-type GaAs semiconductor layer.

Photocatalytic oxidation of organic compounds in a hybrid system composed of a molecular catalyst and visible light-absorbing semiconductor.

PubMed

Zhou, Xu; Li, Fei; Li, Xiaona; Li, Hua; Wang, Yong; Sun, Licheng

2015-01-14

Photocatalytic oxidation of organic compounds proceeded efficiently in a hybrid system with ruthenium aqua complexes as catalysts, BiVO4 as a light absorber, [Co(NH3)5Cl](2+) as a sacrificial electron acceptor and water as an oxygen source. The photogenerated holes in the semiconductor are used to oxidize molecular catalysts into the high-valent Ru(IV)=O intermediates for 2e(-) oxidation.

Heteroepitaxial growth of 3-5 semiconductor compounds by metal-organic chemical vapor deposition for device applications

NASA Technical Reports Server (NTRS)

Collis, Ward J.; Abul-Fadl, Ali

1988-01-01

The purpose of this research is to design, install and operate a metal-organic chemical vapor deposition system which is to be used for the epitaxial growth of 3-5 semiconductor binary compounds, and ternary and quaternary alloys. The long-term goal is to utilize this vapor phase deposition in conjunction with existing current controlled liquid phase epitaxy facilities to perform hybrid growth sequences for fabricating integrated optoelectronic devices.

Metal organic chemical vapor deposition of 111-v compounds on silicon

DOEpatents

Vernon, Stanley M.

1986-01-01

Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

Electrochemical photovoltaic cell having ternary alloy film

DOEpatents

Russak, Michael A.

1984-01-01

A thin film compound semiconductor electrode comprising CdSe.sub.1-x Te.sub.x (0.ltoreq.x.ltoreq.1) is deposited on a transparent conductive substrate. An electrolyte contacts the film to form a photoactive site. The semiconductor material has a narrow energy bandgap permitting high efficiency for light conversion. The film may be fabricated by: (1) co-evaporation of two II-VI group compounds with a common cation, or (2) evaporation of three elements, concurrenty.

Optimum Concentration Ratio Analysis Using Dynamic Thermal Model for Concentrated Photovoltaic System

DTIC Science & Technology

2012-03-22

covalent bond with four adjacent atoms. Compound semiconductors such as GaAs have a crystal lattice similar to the diamond lattice, but since the...are found in both elemental (e.g. Si) and compound form (e.g. GaAs), but every semiconductor material is characterized by the properties of its crystal...lattice. The covalent bonds formed within a semiconducting material determine the shape of the crystal lattice [8]. For an in depth explanation

An analysis of phonon emission as controlled by the combined interaction with the acoustic and piezoelectric phonons in a degenerate III-V compound semiconductor using an approximated Fermi-Dirac distribution at low lattice temperatures

NASA Astrophysics Data System (ADS)

Basu, A.; Das, B.; Middya, T. R.; Bhattacharya, D. P.

2018-03-01

Compound semiconductors being piezoelectric in nature, the intrinsic thermal vibration of the lattice atoms at any temperature gives rise to an additional potential field that perturbs the periodic potential field of the atoms. This is over and above the intrinsic deformation acoustic potential field which is always produced in every material. The scattering of the electrons through the piezoelectric perturbing potential is important in all compound semiconductors, particularly at the low lattice temperatures. Thus, the electrical transport in such materials is principally controlled by the combined interaction of the electrons with the deformation potential acoustic and piezoelectric phonons at low lattice temperatures. The study here, deals with the problem of phonon growth characteristics, considering the combined scattering of the non-equilibrium electrons in compound semiconductors, at low lattice temperatures. Beside degeneracy, other low temperature features, like the inelasticity of the electron-phonon collisions, and the full form of the phonon distribution have been duly considered. The distribution function of the degenerate ensemble of carriers, as given by the heated Fermi-Dirac function, has been approximated by a simplified, well-tested model. The model which has been proposed earlier, makes it much easier to carry out analytically the integrations without usual oversimplified approximations.

Radiation hardening of MOS devices by boron. [for stabilizing gate threshold potential of field effect device

NASA Technical Reports Server (NTRS)

Danchenko, V. (Inventor)

1974-01-01

A technique is described for radiation hardening of MOS devices and specifically for stabilizing the gate threshold potential at room temperature of a radiation subjected MOS field-effect device with a semiconductor substrate, an insulating layer of oxide on the substrate, and a gate electrode disposed on the insulating layer. The boron is introduced within a layer of the oxide of about 100 A-300 A thickness immediately adjacent the semiconductor-insulator interface. The concentration of boron in the oxide layer is preferably maintained on the order of 10 to the 18th power atoms/cu cm. The technique serves to reduce and substantially annihilate radiation induced positive gate charge accumulations.

Producing Silicon Carbide for Semiconductor Devices

NASA Technical Reports Server (NTRS)

Hsu, G. C.; Rohatgi, N. K.

1986-01-01

Processes proposed for production of SiC crystals for use in semiconductors operating at temperatures as high as 900 degrees C. Combination of new processes produce silicon carbide chips containing epitaxial layers. Chips of SiC first grown on porous carbon matrices, then placed in fluidized bed, where additional layer of SiC grows. Processes combined to yield complete process. Liquid crystallization process used to make SiC particles or chips for fluidized-bed process.

Inelastic tunnel diodes

NASA Technical Reports Server (NTRS)

Anderson, L. M. (Inventor)

1984-01-01

Power is extracted from plasmons, photons, or other guided electromagnetic waves at infrared to midultraviolet frequencies by inelastic tunneling in metal-insulator-semiconductor-metal diodes. Inelastic tunneling produces power by absorbing plasmons to pump electrons to higher potential. Specifically, an electron from a semiconductor layer absorbs a plasmon and simultaneously tunnels across an insulator into metal layer which is at higher potential. The diode voltage determines the fraction of energy extracted from the plasmons; any excess is lost to heat.

Visible-wavelength semiconductor lasers and arrays

DOEpatents

Schneider, R.P. Jr.; Crawford, M.H.

1996-09-17

The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1{lambda}) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%. 5 figs.

Stabilized CdSe-CoPi composite photoanode for light-assisted water oxidation by transformation of a CdSe/cobalt metal thin film.

PubMed

Costi, Ronny; Young, Elizabeth R; Bulović, Vladimir; Nocera, Daniel G

2013-04-10

Integration of water splitting catalysts with visible-light-absorbing semiconductors would enable direct solar-energy-to-fuel conversion schemes such as those based on water splitting. A disadvantage of some common semiconductors that possess desirable optical bandgaps is their chemical instability under the conditions needed for oxygen evolution reaction (OER). In this study, we demonstrate the dual benefits gained from using a cobalt metal thin-film as the precursor for the preparation of cobalt-phosphate (CoPi) OER catalyst on cadmium chalcogenide photoanodes. The cobalt layer protects the underlying semiconductor from oxidation and degradation while forming the catalyst and simultaneously facilitates the advantageous incorporation of the cadmium chalcogenide layer into the CoPi layer during continued processing of the electrode. The resulting hybrid material forms a stable photoactive anode for light-assisted water splitting.

Power module packaging with double sided planar interconnection and heat exchangers

DOEpatents

Liang, Zhenxian; Marlino, Laura D.; Ning, Puqi; Wang, Fei

2015-05-26

A double sided cooled power module package having a single phase leg topology includes two IGBT and two diode semiconductor dies. Each IGBT die is spaced apart from a diode semiconductor die, forming a switch unit. Two switch units are placed in a planar face-up and face-down configuration. A pair of DBC or other insulated metallic substrates is affixed to each side of the planar phase leg semiconductor dies to form a sandwich structure. Attachment layers are disposed on outer surfaces of the substrates and two heat exchangers are affixed to the substrates by rigid bond layers. The heat exchangers, made of copper or aluminum, have passages for carrying coolant. The power package is manufactured in a two-step assembly and heating process where direct bonds are formed for all bond layers by soldering, sintering, solid diffusion bonding or transient liquid diffusion bonding, with a specially designed jig and fixture.

Complexes of dipolar excitons in layered quasi-two-dimensional nanostructures

NASA Astrophysics Data System (ADS)

Bondarev, Igor V.; Vladimirova, Maria R.

2018-04-01

We discuss neutral and charged complexes (biexcitons and trions) formed by indirect excitons in layered quasi-two-dimensional semiconductor heterostructures. Indirect excitons—long-lived neutral Coulomb-bound pairs of electrons and holes of different layers—have been known for semiconductor coupled quantum wells and have recently been reported for van der Waals heterostructures such as double bilayer graphene and transition-metal dichalcogenides. Using the configuration space approach, we derive the analytical expressions for the trion and biexciton binding energies as a function of interlayer distance. The method captures essential kinematics of complex formation to reveal significant binding energies, up to a few tens of meV for typical interlayer distances ˜3 -5 Å , with the trion binding energy always being greater than that of the biexciton. Our results can contribute to the understanding of more complex many-body phenomena such as exciton Bose-Einstein condensation and Wigner-like electron-hole crystallization in layered semiconductor heterostructures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zhemin; Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552; Taguchi, Dai

The details of turnover process of spontaneous polarization and associated carrier motions in indium-tin oxide/poly-(vinylidene-trifluoroethylene)/pentacene/Au capacitor were analyzed by coupling displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement. A model was set up from DCM results to depict the relationship between electric field in semiconductor layer and applied external voltage, proving that photo illumination effect on the spontaneous polarization process lied in variation of semiconductor conductivity. The EFISHG measurement directly and selectively probed the electric field distribution in semiconductor layer, modifying the model and revealing detailed carrier behaviors involving photo illumination effect, dipole reversal, and interfacial chargingmore » in the device. A further decrease of DCM current in the low voltage region under illumination was found as the result of illumination effect, and the result was argued based on the changing of the total capacitance of the double-layer capacitors.« less

Semiconductor light-emitting devices having concave microstructures providing improved light extraction efficiency and method for producing same

DOEpatents

Tansu, Nelson; Gilchrist, James F; Ee, Yik-Khoon; Kumnorkaew, Pisist

2013-11-19

A conventional semiconductor LED is modified to include a microlens layer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.

Emission characteristics of volatile organic compounds from semiconductor manufacturing.

PubMed

Chein, HungMin; Chen, Tzu Ming

2003-08-01

A huge amount of volatile organic compounds (VOCs) is produced and emitted with waste gases from semiconductor manufacturing processes, such as cleaning, etching, and developing. VOC emissions from semiconductor factories located at Science-Based Industrial Park, Hsin-chu, Taiwan, were measured and characterized in this study. A total of nine typical semiconductor fabricators (fabs) were monitored over a 12-month period (October 2000-September 2001). A flame ionization analyzer was employed to measure the VOC emission rate continuously in a real-time fashion. The amount of chemical use was adopted from the data that were reported to the Environmental Protection Bureau in Hsin-chu County as per the regulation of the Taiwan Environmental Protection Administration. The VOC emission factor, defined as the emission rate (kg/month) divided by the amount of chemical use (L/month), was determined to be 0.038 +/- 0.016 kg/L. A linear regression equation is proposed to fit the data with the correlation coefficient (R2)=0.863. The emission profiles of VOCs, which were drawn using the gas chromatograph/mass spectrometer analysis method, show that isopropyl alcohol is the dominant compound in most of the fabs.

Exploration of stable compounds, crystal structures, and superconductivity in the Be-H system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Shuyin, E-mail: yushuyin2014@gmail.com; Zeng, Qingfeng; Zhang, Litong

2014-10-15

Using first-principles variable-composition evolutionary methodology, we explored the high-pressure structures of beryllium hydrides between 0 and 400 GPa. We found that BeH{sub 2} remains the only stable compound in this pressure range. The pressure-induced transformations are predicted as Ibam→P3{sup -}m1→R3{sup -}m→Cmcm→P4/nmm, which occur at 24, 139, 204 and 349 GPa, respectively. P3{sup -}m1 and R3{sup -}m structures are layered polytypes based on close packings of H atoms with Be atoms filling all octahedral voids in alternating layers. Cmcm and P4/nmm contain two-dimensional triangular networks with each layer forming a kinked slab in the ab-plane. P3{sup -}m1 and R3{sup -}m aremore » semiconductors while Cmcm and P4/nmm are metallic. We have explored superconductivity of both metal phases, and found large electron-phonon coupling parameters of λ = 0.63 for Cmcm with a T{sub c} of 32.1-44.1 K at 250 GPa and λ = 0.65 for P4/nmm with a T{sub c} of 46.1-62.4 K at 400 GPa. The dependence of T{sub c} on pressure indicates that T{sub c} initially increases to a maximum of 45.1 K for Cmcm at 275 GPa and 97.0 K for P4/nmm at 365 GPa, and then decreases with increasing pressure for both phases.« less

Subnanosecond Scintillation Detector

NASA Technical Reports Server (NTRS)

Hoenk, Michael (Inventor); Hennessy, John (Inventor); Hitlin, David (Inventor)

2017-01-01

A scintillation detector, including a scintillator that emits scintillation; a semiconductor photodetector having a surface area for receiving the scintillation, wherein the surface area has a passivation layer configured to provide a peak quantum efficiency greater than 40% for a first component of the scintillation, and the semiconductor photodetector has built in gain through avalanche multiplication; a coating on the surface area, wherein the coating acts as a bandpass filter that transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths; and wherein the surface area, the passivation layer, and the coating are controlled to increase the temporal resolution of the semiconductor photodetector.

Laser ablation mechanism of transparent layers on semiconductors with ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Rublack, Tino; Hartnauer, Stefan; Mergner, Michael; Muchow, Markus; Seifert, Gerhard

2011-12-01

Transparent dielectric layers on semiconductors are used as anti-reflection coatings both for photovoltaic applications and for mid-infrared optical elements. We have shown recently that selective ablation of such layers is possible using ultrashort laser pulses at wavelengths being absorbed by the semiconductor. To get a deeper understanding of the ablation mechanism, we have done ablation experiments for different transparent materials, in particular SiO2 and SixNy on silicon, using a broad range of wavelengths ranging from UV to IR, and pulse durations between 50 and 2000 fs. The characterization of the ablated regions was done by light microscopy and atomic force microscopy (AFM). Utilizing laser wavelengths above the silicon band gap, selective ablation of the dielectric layer without noticeable damage of the opened silicon surface is possible. In contrast, ultrashort pulses (1-2 ps) at mid-infrared wavelengths already cause damage in the silicon at lower intensities than in the dielectric layer, even when a vibrational resonance (e.g. at λ = 9.26 μm for SiO2) is addressed. The physical processes behind this, on the first glance counterintuitive, observation will be discussed.

Optoelectronics of supported and suspended 2D semiconductors

NASA Astrophysics Data System (ADS)

Bolotin, Kirill

2014-03-01

Two-dimensional semiconductors, materials such monolayer molybdenum disulfide (MoS2) are characterized by strong spin-orbit and electron-electron interactions. However, both electronic and optoelectronic properties of these materials are dominated by disorder-related scattering. In this talk, we investigate approaches to reduce scattering and explore physical phenomena arising in intrinsic 2D semiconductors. First, we discuss fabrication of pristine suspended monolayer MoS2 and use photocurrent spectroscopy measurements to study excitons in this material. We observe band-edge and van Hove singularity excitons and estimate their binding energies. Furthermore, we study dissociation of these excitons and uncover the mechanism of their contribution to photoresponse of MoS2. Second, we study strain-induced modification of bandstructures of 2D semiconductors. With increasing strain, we find large and controllable band gap reduction of both single- and bi-layer MoS2. We also detect experimental signatures consistent with strain-induced transition from direct to indirect band gap in monolayer MoS2. Finally, we fabricate heterostructures of dissimilar 2D semiconductors and study their photoresponse. For closely spaced 2D semiconductors we detect charge transfer, while for separation larger than 10nm we observe Forster-like energy transfer between excitations in different layers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veselov, D. A., E-mail: dmitriy90@list.ru; Shashkin, I. S.; Bakhvalov, K. V.

Semiconductor lasers based on MOCVD-grown AlGaInAs/InP separate-confinement heterostructures are studied. It is shown that raising only the energy-gap width of AlGaInAs-waveguides without the introduction of additional barriers results in more pronounced current leakage into the cladding layers. It is found that the introduction of additional barrier layers at the waveguide–cladding-layer interface blocks current leakage into the cladding layers, but results in an increase in the internal optical loss with increasing pump current. It is experimentally demonstrated that the introduction of blocking layers makes it possible to obtain maximum values of the internal quantum efficiency of stimulated emission (92%) and continuouswavemore » output optical power (3.2 W) in semiconductor lasers in the eye-safe wavelength range (1400–1600 nm).« less

Cu2O-based solar cells using oxide semiconductors

NASA Astrophysics Data System (ADS)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2016-01-01

We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu2O heterojunction solar cells fabricated using p-type Cu2O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu2O sheets under various deposition conditions using a pulsed laser deposition method. In Cu2O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa2O4 thin-film layer. In most of the Cu2O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga2O3-Al2O3 systems, higher conversion efficiencies (η) as well as a high open circuit voltage (Voc) were obtained by using a relatively small amount of MgO or Al2O3, e.g., (ZnO)0.91-(MgO)0.09 and (Ga2O3)0.975-(Al2O3)0.025, respectively. When Cu2O-based heterojunction solar cells were fabricated using Al2O3-Ga2O3-MgO-ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high Voc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu2O heterojunction solar cells fabricated using Na-doped Cu2O (Cu2O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a Voc of 0.84 V were obtained in a MgF2/AZO/n-(Ga2O3-Al2O3)/p-Cu2O:Na heterojunction solar cell fabricated using a Cu2O:Na sheet with a resistivity of approximately 10 Ω·cm and a (Ga0.975Al0.025)2O3 thin film with a thickness of approximately 60 nm. In addition, a Voc of 0.96 V and an η of 5.4% were obtained in a MgF2/AZO/n-AGMZO/p-Cu2O:Na heterojunction solar cell.

Junction formation of Cu3BiS3 investigated by Kelvin probe force microscopy and surface photovoltage measurements

PubMed Central

Mesa, Fredy; Chamorro, William; Vallejo, William; Baier, Robert; Dittrich, Thomas; Grimm, Alexander; Lux-Steiner, Martha C

2012-01-01

Summary Recently, the compound semiconductor Cu3BiS3 has been demonstrated to have a band gap of ~1.4 eV, well suited for photovoltaic energy harvesting. The preparation of polycrystalline thin films was successfully realized and now the junction formation to the n-type window needs to be developed. We present an investigation of the Cu3BiS3 absorber layer and the junction formation with CdS, ZnS and In2S3 buffer layers. Kelvin probe force microscopy shows the granular structure of the buffer layers with small grains of 20–100 nm, and a considerably smaller work-function distribution for In2S3 compared to that of CdS and ZnS. For In2S3 and CdS buffer layers the KPFM experiments indicate negatively charged Cu3BiS3 grain boundaries resulting from the deposition of the buffer layer. Macroscopic measurements of the surface photovoltage at variable excitation wavelength indicate the influence of defect states below the band gap on charge separation and a surface-defect passivation by the In2S3 buffer layer. Our findings indicate that Cu3BiS3 may become an interesting absorber material for thin-film solar cells; however, for photovoltaic application the band bending at the charge-selective contact has to be increased. PMID:22497001

Transport Properties of ZnSe- ITO Hetero Junction

NASA Astrophysics Data System (ADS)

Ichibakase, Tsuyoshi

In this report, ITO(Indium Tin Oxide) was used on the glass substrates as the transparent electrode, and ZnSe layer was prepared by the vacuum deposition on this ITO. Then, the electrical characteristics of this sample were investigated by mans of the electric current transport analysis. The sample that ZnSe was prepared as 3.4 μm in case of ITO-ZnSe sample, has high density level at the junction surface. The ITO-ZnSe junction has two type of diffusion current. However, the ITO-ZnSe sample that ZnSe layer was prepared as 0.1 μm can be assumed as the ohmic contact, and ITO-ZnSe(0.1μm) -CdTe sample shows the avalanche breakdown, and it is considered that the avalanche breakdown occurs in CdTe layer. It is difficult to occur the avalanche breakdown, if ZnSe-CdTe junction has high-density level and CdTe layer has high-density defect. Hence, the ZnSe-CdTe sample that CdTe layer was prepared on ITO-ZnSe(0.1μm) substrate has not high-density level at the junction surface, and the CdTe layer with little lattice imperfection can be prepared. It found that ITO-ZnSe(0.1μm) substrate is available for the II-VI compounds semiconductor device through above analysis result.

Junction formation of Cu(3)BiS(3) investigated by Kelvin probe force microscopy and surface photovoltage measurements.

PubMed

Mesa, Fredy; Chamorro, William; Vallejo, William; Baier, Robert; Dittrich, Thomas; Grimm, Alexander; Lux-Steiner, Martha C; Sadewasser, Sascha

2012-01-01

Recently, the compound semiconductor Cu(3)BiS(3) has been demonstrated to have a band gap of ~1.4 eV, well suited for photovoltaic energy harvesting. The preparation of polycrystalline thin films was successfully realized and now the junction formation to the n-type window needs to be developed. We present an investigation of the Cu(3)BiS(3) absorber layer and the junction formation with CdS, ZnS and In(2)S(3) buffer layers. Kelvin probe force microscopy shows the granular structure of the buffer layers with small grains of 20-100 nm, and a considerably smaller work-function distribution for In(2)S(3) compared to that of CdS and ZnS. For In(2)S(3) and CdS buffer layers the KPFM experiments indicate negatively charged Cu(3)BiS(3) grain boundaries resulting from the deposition of the buffer layer. Macroscopic measurements of the surface photovoltage at variable excitation wavelength indicate the influence of defect states below the band gap on charge separation and a surface-defect passivation by the In(2)S(3) buffer layer. Our findings indicate that Cu(3)BiS(3) may become an interesting absorber material for thin-film solar cells; however, for photovoltaic application the band bending at the charge-selective contact has to be increased.

Photo-Spectrometer Realized In A Standard Cmos Ic Process

DOEpatents

Simpson, Michael L.; Ericson, M. Nance; Dress, William B.; Jellison, Gerald E.; Sitter, Jr., David N.; Wintenberg, Alan L.

1999-10-12

A spectrometer, comprises: a semiconductor having a silicon substrate, the substrate having integrally formed thereon a plurality of layers forming photo diodes, each of the photo diodes having an independent spectral response to an input spectra within a spectral range of the semiconductor and each of the photo diodes formed only from at least one of the plurality of layers of the semiconductor above the substrate; and, a signal processing circuit for modifying signals from the photo diodes with respective weights, the weighted signals being representative of a specific spectral response. The photo diodes have different junction depths and different polycrystalline silicon and oxide coverings. The signal processing circuit applies the respective weights and sums the weighted signals. In a corresponding method, a spectrometer is manufactured by manipulating only the standard masks, materials and fabrication steps of standard semiconductor processing, and integrating the spectrometer with a signal processing circuit.

Hetero-junction photovoltaic device and method of fabricating the device

DOEpatents

Aytug, Tolga; Christen, David K; Paranthaman, Mariappan Parans; Polat, Ozgur

2014-02-10

A hetero-junction device and fabrication method in which phase-separated n-type and p-type semiconductor pillars define vertically-oriented p-n junctions extending above a substrate. Semiconductor materials are selected for the p-type and n-type pillars that are thermodynamically stable and substantially insoluble in one another. An epitaxial deposition process is employed to form the pillars on a nucleation layer and the mutual insolubility drives phase separation of the materials. During the epitaxial deposition process, the orientation is such that the nucleation layer initiates propagation of vertical columns resulting in a substantially ordered, three-dimensional structure throughout the deposited material. An oxidation state of at least a portion of one of the p-type or the n-type semiconductor materials is altered relative to the other, such that the band-gap energy of the semiconductor materials differ with respect to stoichiometric compositions and the device preferentially absorbs particular selected bands of radiation.

Chitin Liquid-Crystal-Templated Oxide Semiconductor Aerogels.

PubMed

Chau, Trang The Lieu; Le, Dung Quang Tien; Le, Hoa Thi; Nguyen, Cuong Duc; Nguyen, Long Viet; Nguyen, Thanh-Dinh

2017-09-13

Chitin nanocrystals have been used as a liquid crystalline template to fabricate layered oxide semiconductor aerogels. Anisotropic chitin liquid crystals are transformed to sponge-like aerogels by hydrothermally cross-linked gelation and lyophilization-induced solidification. The hydrothermal gelation of chitin aqueous suspensions then proceeds with peroxotitanate to form hydrogel composites that recover to form aerogels after freeze-drying. The homogeneous peroxotitanate/chitin composites are calcined to generate freestanding titania aerogels that exhibit the nanostructural integrity of layered chitin template. Our extended investigations show that coassembling chitin nanocrystals with other metal-based precursors also yielded semiconductor aerogels of perovskite BaTiO 3 and CuO x nanocrystals. The potential of these materials is great to investigate these chitin sponges for biomedicine and these semiconductor aerogels for photocatalysis, gas sensing, and other applications. Our results present a new aerogel templating method of highly porous, ultralight materials with chitin liquid crystals.

Exchanging Ohmic Losses in Metamaterial Absorbers with Useful Optical Absorption for Photovoltaics

PubMed Central

Vora, Ankit; Gwamuri, Jephias; Pala, Nezih; Kulkarni, Anand; Pearce, Joshua M.; Güney, Durdu Ö.

2014-01-01

Using metamaterial absorbers, we have shown that metallic layers in the absorbers do not necessarily constitute undesired resistive heating problem for photovoltaics. Tailoring the geometric skin depth of metals and employing the natural bulk absorbance characteristics of the semiconductors in those absorbers can enable the exchange of undesired resistive losses with the useful optical absorbance in the active semiconductors. Thus, Ohmic loss dominated metamaterial absorbers can be converted into photovoltaic near-perfect absorbers with the advantage of harvesting the full potential of light management offered by the metamaterial absorbers. Based on experimental permittivity data for indium gallium nitride, we have shown that between 75%–95% absorbance can be achieved in the semiconductor layers of the converted metamaterial absorbers. Besides other metamaterial and plasmonic devices, our results may also apply to photodectors and other metal or semiconductor based optical devices where resistive losses and power consumption are important pertaining to the device performance. PMID:24811322

The Research Laboratory of Electronics Progress Report Number 133, January 1-December 1990

DTIC Science & Technology

1990-12-31

4 6 Chapter 7 High-Frequency InAlAs/InGaAs Metal -Insulator-Doped Semiconductor...Epitaxy of Compound Semiconductors Chapter 7 High-Frequency InAlAs/InGaAs Metal -Insulator- Doped Semiconductor Field-Effect Transistors (MIDFETs) for...aligned silicided NMOS posed of refractory metals to allow a subsequentdevice fabrication. We have used cobalt deposi- high temperature anneal. This

Research Update: Photoelectrochemical water splitting and photocatalytic hydrogen production using ferrites (MFe2O4) under visible light irradiation

NASA Astrophysics Data System (ADS)

Dillert, Ralf; Taffa, Dereje H.; Wark, Michael; Bredow, Thomas; Bahnemann, Detlef W.

2015-10-01

The utilization of solar light for the photoelectrochemical and photocatalytic production of molecular hydrogen from water is a scientific and technical challenge. Semiconductors with suitable properties to promote solar-driven water splitting are a desideratum. A hitherto rarely investigated group of semiconductors are ferrites with the empirical formula MFe2O4 and related compounds. This contribution summarizes the published results of the experimental investigations on the photoelectrochemical and photocatalytic properties of these compounds. It will be shown that the potential of this group of compounds in regard to the production of solar hydrogen has not been fully explored yet.

Two-dimensional transition metal dichalcogenides as atomically thin semiconductors: opportunities and challenges.

PubMed

Duan, Xidong; Wang, Chen; Pan, Anlian; Yu, Ruqin; Duan, Xiangfeng

2015-12-21

The discovery of graphene has ignited intensive interest in two-dimensional layered materials (2DLMs). These 2DLMs represent a new class of nearly ideal 2D material systems for exploring fundamental chemistry and physics at the limit of single-atom thickness, and have the potential to open up totally new technological opportunities beyond the reach of existing materials. In general, there are a wide range of 2DLMs in which the atomic layers are weakly bonded together by van der Waals interactions and can be isolated into single or few-layer nanosheets. The van der Waals interactions between neighboring atomic layers could allow much more flexible integration of distinct materials to nearly arbitrarily combine and control different properties at the atomic scale. The transition metal dichalcogenides (TMDs) (e.g., MoS2, WSe2) represent a large family of layered materials, many of which exhibit tunable band gaps that can undergo a transition from an indirect band gap in bulk crystals to a direct band gap in monolayer nanosheets. These 2D-TMDs have thus emerged as an exciting class of atomically thin semiconductors for a new generation of electronic and optoelectronic devices. Recent studies have shown exciting potential of these atomically thin semiconductors, including the demonstration of atomically thin transistors, a new design of vertical transistors, as well as new types of optoelectronic devices such as tunable photovoltaic devices and light emitting devices. In parallel, there have also been considerable efforts in developing diverse synthetic approaches for the rational growth of various forms of 2D materials with precisely controlled chemical composition, physical dimension, and heterostructure interface. Here we review the recent efforts, progress, opportunities and challenges in exploring the layered TMDs as a new class of atomically thin semiconductors.

Twisted bilayer blue phosphorene: A direct band gap semiconductor

NASA Astrophysics Data System (ADS)

Ospina, D. A.; Duque, C. A.; Correa, J. D.; Suárez Morell, Eric

2016-09-01

We report that two rotated layers of blue phosphorene behave as a direct band gap semiconductor. The optical spectrum shows absorption peaks in the visible region of the spectrum and in addition the energy of these peaks can be tuned with the rotational angle. These findings makes twisted bilayer blue phosphorene a strong candidate as a solar cell or photodetection device. Our results are based on ab initio calculations of several rotated blue phosphorene layers.

Blending effect of 6,13-bis(triisopropylsilylethynyl) pentacene-graphene composite layers for flexible thin film transistors with a polymer gate dielectric.

PubMed

Basu, Sarbani; Adriyanto, Feri; Wang, Yeong-Her

2014-02-28

Solution processible poly(4-vinylphenol) is employed as a transistor dielectric material for low cost processing on flexible substrates at low temperatures. A 6,13-bis (triisopropylsilylethynyl) (TIPS) pentacene-graphene hybrid semiconductor is drop cast to fabricate bottom-gate and bottom-contact field-effect transistor devices on flexible and glass substrates under an ambient air environment. A few layers of graphene flakes increase the area in the conduction channel, and form bridge connections between the crystalline regions of the semiconductor layer which can change the surface morphology of TIPS pentacene films. The TIPS pentacene-graphene hybrid semiconductor-based organic thin film transistors (OTFTs) cross-linked with a poly(4-vinylphenol) gate dielectric exhibit an effective field-effect mobility of 0.076 cm(2) V(-1) s(-1) and a threshold voltage of -0.7 V at V(gs) = -40 V. By contrast, typical TIPS pentacene shows four times lower mobility of 0.019 cm(2) V(-1) s(-1) and a threshold voltage of 5 V. The graphene/TIPS pentacene hybrids presented in this paper can enhance the electrical characteristics of OTFTs due to their high crystallinity, uniform large-grain distribution, and effective reduction of crystal misorientation of the organic semiconductor layer, as confirmed by x-ray diffraction spectroscopy, atomic force microscopy, and optical microscopy studies.