Abstract: An AlGaN composition is provided comprising a group III-Nitride active region layer, for use in an active region of a UV light emitting device, wherein light-generation occurs through radiative recombination of carriers in nanometer scale size, compositionally inhomogeneous regions having band-gap energy less than the surrounding material. Further, a semiconductor UV light emitting device having an active region layer comprised of the AlGaN composition above is provided, as well as a method of producing the AlGaN composition and semiconductor UV light emitting device, involving molecular beam epitaxy.

Abstract: Methods and devices for creating an anisotropic strain in a semiconductor quantum well structure to induce anisotropy thereof are disclosed herein. Initially, a substrate is provided, and a quantum well structure formed upon the substrate. A first crystalline layer (e.g., a GaAs layer) having a first crystalline phase can then be deposited upon the quantum well structure. Thereafter, a second crystalline layer (e.g., a GaN layer) having a second crystalline phase and a thickness thereof can be formed upon the first crystalline layer to thereby induce an anisotropic strain in the quantum well structure to produce a quantum well device thereof. Additionally, the second crystalline layer (e.g., GaN) can be formed from a transparent material and utilized as an anti-reflection layer. By properly choosing the thickness of the second crystalline layer (e.g., a GaN layer), a desired anisotropic strain as well as a desired anti-reflection wavelength can be achieved.

Abstract: Porous silicon is formed by patterning a single crystal silicon substrate prior to electrochemically etching the same. The process is a controlled method of fabricating silicon microstructures which exhibit luminescence and are useful in optoelectronic devices, such as light emitting diodes. The porous silicon produced has a high degree of uniformity and repeatability.

Abstract: An opto-electronic semiconductor device including a variable strained layered quantum well structure having at least two superimposed heavy- and light-hole triangular bottom valance band quantum wells with mutually opposite slopes. Upon the application of a bias potential across a thickness dimension of the quantum wells, an electric field is generated therethrough which produces an interchange of the confined energy levels of heavy-holes and light-holes in the quantum wells which causes a change in the transmission characteristics of light passing through the device as a result of the heavy- and light-hole energy bands having different light absorption anisotropy.

Abstract: An optic modulator having a transparent piezoelectric substrate, an active multiple quantum well (MQW) epilayer with bottom electrical contacts bonded to the substrate, wherein the substrate is cut such that its thermal expansion coefficient is matched or roughly matched to that of the MQW epilayer in the direction parallel to the long axes of the bottom contacts and so that the piezoelectrically-active direction of the substrate is normal to the long axes of the bottom contacts. In order to control the bias of the MQW epilayer a transparent contact is disposed over the MQW epilayer. In operation, the piezoelectric substrate, when activated, will displace an anisotropic strain on the MQW epilayer which will break the rotational symmetry in the plane of the MQW. This will result in anisotropic mixing of the heavy and light holes in the MQW epilayer and thus, will result in an anisotropic excitonic absorption of light normal to the MQW epilayer.

Abstract: The present invention is a spatial light modulator which uses an uniaxially trained multiple quantum well (MQW) structure with an anisotropic absorption to rotate the polarization of light normal to the MQW structure. The anisotropy which produces this rotation is the result of a thermally induced in-plane anisotropic strain. The MQW light modulator based on this process has a high contrast ratio of 7000:1 and increased speed as compared to other similar modulators.

Abstract: A multiple quantum well optical modulator comprising a multiple quantum well structure embedded in the intrinsic region of an s-i-n+ semiconductor. The s-i-n+ structure causes an electric field to be applied to the multiple quantum well structure which causes uncoupling of the el energy confined level of one layer and the x level of the adjacent layer, thereby changing the absorption of the light and causing modulation thereof.

Abstract: An optic modulator which employs strained multiple quantum well structures which are fabricated and spaced from one another such that the stress perpendicular to the direction of the spacing is released leaving only a uniaxial stress along the direction parallel to the spacing. The multiple quantum well structures are then sandwiched between two optic polarizers which are aligned perpendicular to one another. At zero electric field, polarized light passing from the first polarizer is further polarized such that the polarization of the light is rotated to pass through the second polarizer. When an electric field is applied across the heterostructure, light passing through the heterostructure is not further polarized and therefore, the optic signal is interrupted. Thus, optic signals may be modulated with the contrast of polarizing modulators at the speed of superlattice heterostructures.

Abstract: A sweeping photoreflectance spectroscopy technique and apparatus is disclosed. This technique and apparatus enable the determination of the band structure of semi conductors and other materials at low temperatures by the mechanism of modulating the photoreflectance signal in a predetermined manner thereby enabling its detection in the presence of a much larger, but continuous, undesirable photoluminescence signal.