Abstract: A photoconducting layered material arrangement for producing or detecting high frequency radiation includes a semiconductor material including an alloy comprised of InGaAs, InGaAsSb, or GaSb, with an admixture of Al, which material is applied to a suitable support substrate in a manner such that the lattices are suitably adjusted, wherewith the semiconductor material comprised of InGaAlAs, InGaAlAsSb, or GaAlSb has a band gap of more than 1 eV, as a consequence of the admixed proportion of Al. The proportion x of Al in the semiconductor material InyGa1-y-xAlxAs is between x=0.2 and x=0.35, wherewith the proportion y of In may be between 0.5 and 0.55. The support substrate is InP or GaAs.

Abstract: A photoconducting layered material arrangement for producing or detecting high frequency radiation includes a semiconductor material including an alloy comprised of InGaAs, InGaAsSb, or GaSb, with an admixture of Al, which material is applied to a suitable support substrate in a manner such that the lattices are suitably adjusted, wherewith the semiconductor material comprised of InGaAlAs, InGaAlAsSb, or GaAlSb has a band gap of more than 1 eV, as a consequence of the admixed proportion of Al. The proportion x of Al in the semiconductor material InyGa1-y-xAlxAs is between x=0.2 and x=0.35, wherewith the proportion y of In may be between 0.5 and 0.55. The support substrate is InP or GaAs.

Abstract: A photoconducting layered material arrangement for producing or detecting high frequency radiation includes a semiconductor material including an alloy comprised of InGaAs, InGaAsSb, or GaSb, with an admixture of Al, which material is applied to a suitable support substrate in a manner such that the lattices are suitably adjusted, wherewith the semiconductor material comprised of InGaAlAs, InGaAlAsSb, or GaAlSb has a band gap of more than 1 eV, as a consequence of the admixed proportion of Al. The proportion x of Al in the semiconductor material InyGa1-y-xAlxAs is between x=0.2 and x=0.35, wherewith the proportion y of in may be between 0.5 and 0.55. The support substrate is InP or GaAs.

Abstract: A photoconducting layered material arrangement for producing or detecting high frequency radiation includes a semiconductor material including an alloy comprised of InGaAs, InGaAsSb, or GaSb, with an admixture of Al, which material is applied to a suitable support substrate in a manner such that the lattices are suitably adjusted, wherewith the semiconductor material comprised of InGaAlAs, InGaAlAsSb, or GaAlSb has a band gap of more than 1 eV, as a consequence of the admixed proportion of Al. The proportion x of Al in the semiconductor material InyGa1?y?xAlxAs is between x=0.2 and x=0.35, wherewith the proportion y of In may be between 0.5 and 0.55. The support substrate is InP or GaAs.

Abstract: Composite epitaxial materials that comprise semimetallic ErAs nanoparticles or nanoislands epitaxially embedded in a semiconducting In0.53Ga0.47As matrix both as superlattices and randomly distributed throughout the matrix are disclosed. The presence of these particles increases the free electron concentration in the material while providing scattering centers for phonons. Electron concentration, mobility, and Seebeck coefficient of these materials are discussed and their potential for use in thermoelectric power generators is postulated. These composite materials in accordance with the present invention have high electrical conductivity, low thermal conductivity, and a high Seebeck coefficient. The ErAs nanoislands provides additional scattering mechanism for the mid to long wavelength phonon—the combination reduces the thermal conductivity below the alloy limit.

Abstract: An ultragrating is a nanometer-period optical grating that is fabricated from a horizontal superlattice. A superlattice is a material structure grown on a substrate by molecular-beam epitaxy or metal-organic chemical vapor deposition and having periodic compositional variations. A horizontal superlattice is one in which the compositional variations are in a direction parallel to the substrate surface. By the selective removal of one of the superlattice materials, an ultragrating is obtained. The smallest grating periods possible before this discovery were those made by electron-beam lithographic techniques which are limited to values greater than 100 nanometers. Thus, the ultragrating with grating periods ranging from one to a hundred nanometers represents an order of magnitude advancement in the state of the art of making optical gratings. The ultragrating will fine utility in the design of advanced electronic devices and for general scientific and engineering purposes.

Abstract: Single GaAs quantum well or single GaAs active layer or single reverse interface structures with Al.sub.x Ga.sub.1-x As barrier layers have improved qualities when one or more narrow bandgap GaAs getter-smoothing layers, which are thin, are grown and are incorporated in the barrier layer before and in close proximity to the active layer.

Abstract: A resonant-tunneling, heterostructure bipolar transistor having a quantum well between emitter contact and collector region is described. In one embodiment, a compositionally graded portion of the emitter region is adjacent to the base region, and there is a double barrier in the base region. In another embodiment the quantum well is defined by the emitter and a potential barrier in the base region. Further embodiments have a quantum well between emitter and collector regions or else within the emitter region.

Abstract: A heterojunction bipolar transistor having means for changing carrier transport properties is described.

Abstract: A method of fabricating quantum well wires and boxes is described in which interdiffusion in a semiconductor having a compositional profile is enhanced by the presence of defects created by ion implantation in localized regions.

Abstract: Semiconductor devices having submonolayer superlattices are described. These devices may have periodic compositional variations in a direction parallel to the substrate surface as well as in the perpendicular direction. Such superlattices are useful in numerous types of devices including lasers, transistors, etc.

Abstract: A device having a selectively doped varying bandgap region with pyroelectric characteristics is described which is useful as a photodetector or temperature sensor. A plurality of selectively doped regions forming a superlattice may also be used. Ferroelectric devices are also described.

Abstract: Single GaAs quantum well or single GaAs active layer or single reverse interface structures with Al.sub.x Ga.sub.1-x As barrier layers have improved qualities when one or more narrow bandgap GaAs getter-smoothing layers, which are thin, are grown and are incorporated in the barrier layer before and in close proximity to the active layer.

Abstract: A semiconductor apparatus is provided. The apparatus has a multiple layer heterostructure having first and second material layers having first and second bandgaps, respectively and a semiconductor layer of a third bandgap being fabricated between said material layers, the bottom of the conduction band of said semiconductor layer is below the bottom of the conduction band of said material layers, and the top of the valence band of said semiconductor layer is above the top of the valence band of said material layers, the thickness of said semiconductor layer is chosen sufficient for carrier confinement effects within said semiconductor layer to influence the optical properties of said multiple layer heterostructure, and means for applying an electric field to the multiple layer heterostructure in order to vary an optical absorption coefficient and an index of refraction of the multiple layer heterostructure in response to the electric field.

Abstract: A unipolar, rectifying semiconductor device is described. Rectification is produced by an asymmetric potential barrier created by a sawtooth-shaped composition profile of Al.sub.x Ga.sub.1-x As between layers of n-type GaAs. Single and multiple barriers, as well as doped and undoped barriers, show rectification. Also described is the incorporation of this type of device in an infrared detector, a hot electron transistor and mixer diodes.

Abstract: Suitably modified molecular beam epitaxy (MBF) techniques are used to synthesize single crystal, periodic monolayer superlattices of semiconductor alloys on single crystal substrates maintained below a critical growth temperature. Described is the fabrication of periodic structures of (GaAs).sub.n (AlAs).sub.m, where m and n are the number of contiguous monolayers of GaAs and AlAs, respectively, in each period of the structure. As many as 10,000 monolayers were grown in a single structure. Also described is the MBE growth of (Al.sub.x Ga.sub.1-x As).sub.n (Ge.sub.2).sub.m, quasi-superlattice and non-superlattice structures depending on the particular values of n, m and the growth temperature. Waveguides, heterostructure lasers and X-ray reflectors using some of the structures are also described.

Abstract: Suitably modified molecular beam epitaxy (MBE) techniques are used to synthesize single crystal, periodic monolayer superlattices of semiconductor alloys on single crystal substrates maintained below a critical growth temperature. Described is the fabrication of periodic structures of (GaAs).sub.n (AlAs).sub.m, where m and n are the number of contiguous monolayers of GaAs and AlAs, respectively, in each period of the structure. As many as 10,000 monolayers were grown in a single structure. Also described is the MBE growth of (Al.sub.x Ga.sub.1-x As).sub.n (Ge.sub.2).sub.m, quasi-superlattice and non-superlattice structures depending on the particular values of n, m and the growth temperature. Waveguides, heterostructure lasers and X-ray reflectors using some of the structures are also described.

Abstract: The mobility of a relatively narrow bandgap semiconductor material can be significantly enhanced by incorporating it into a multilayered structure (10) comprising a first plurality of relatively narrow bandgap layers (12) of the material and a second plurality of wider bandgap semiconductor layers (14) interleaved with and contiguous with the first plurality. The wide bandgap and narrow bandgap layers are substantially lattice-matched to one another, and the wide bandgap layers are doped such that the impurity concentration-thickness product therein is greater than the same product in the narrow bandgap layers. The fabrication of the structure by MBE to enhance the mobility of GaAs is specifically described. In this case, the narrow bandgap layers (12) comprise GaAs and are unintentionally doped to about 10.sup.14 /cm.sup.3, whereas the wide bandgap layers (14) comprise AlGaAs doped n-type to about 10.sup.16 to 10.sup.18 /cm.sup.3. The incorporation of this structure in an FET is also described.

Abstract: The mobility of a relatively narrow bandgap semiconductor material can be significantly enhanced by incorporating it into a multilayered structure (10) comprising a first plurality of relatively narrow bandgap layers (12) of the material and a second plurality of wider bandgap semiconductor layers (14) interleaved with and contiguous with the first plurality. The wide bandgap and narrow bandgap layers are substantially lattice-matched to one another, and the wide bandgap layers are doped such that the impurity concentration-thickness product therein is greater than the same product in the narrow bandgap layers. The fabrication of the structure by MBE to enhance the mobility of GaAs is specifically described. In this case, the narrow bandgap layers (12) comprise GaAs and are unintentionally doped to about 10.sup.14 /cm.sup.3, whereas the wide bandgap layers (14) comprise AlGaAs doped n-type to about 10.sup.16 to 10.sup.18 /cm.sup.3. The incorporation of this structure in an FET is also described.