Abstract: Compound semiconductor material is irradiated with x-ray radiation to activate a dopant material. Active carrier concentration efficiency may be improved over known methods, including conventional thermal annealing. The method may be employed for III-V group compounds, including GaN-based semiconductors, doped with p-type material to form low resistivity p-GaN. The method may be further employed to manufacture GaN-based LEDs, including blue LEDs, having improved forward bias voltage and light-emitting efficiency.

Abstract: A novel E. coli strain which can produce L-phenylalanine and is resistant to high osmotic pressure and a process for producing L-phenylalanine by use of the novel E. coli (KCCM 10,016) are disclosed.

Abstract: A process for the preparation of .alpha.-L-aspartyl-L-phenylalanine methyl ester in high yield, which comprises the steps of esterifying L-phenylalanine with methanol while undergoing continuous evaporation to remove the water formed during esterification, coupling the produced L-phenylalanine methyl ester with N-formyl-L-aspartic anhydride, deformylating the produced N-formyl-L-aspartyl-L-phenylalanine methyl ester, crystallizing the formed .alpha.-L-aspartyl-L-phenylalanine methyl ester as .alpha.-L-aspartyl-L-phenylalanine methyl ester hydrochloric acid salt, recovering the first .alpha.-L-aspartyl-L-phenylalanine methyl ester hydrochloric acid salt, esterifying .alpha.-L-aspartyl-L-phenylalanine in the filtrate to produce the second .alpha.-L-aspartyl-L-phenylalanine methyl ester, and combining the first and second .alpha.-L-aspartyl-L-phenylalanine methyl ester product.

Abstract: An eye-safe short pulse room-temperature solid state laser emitting at about 2.1 microns is optically pumped by diode lasers emitting at about 1.9 microns Absorption spectra of Ho ions in YAG (Yttrium Aluminum Garnet) and YLF (Yttrium Lithium Fluoride) host crystals are described. Optical pumping is performed by high-power diode lasers emitting at about 1.91 microns consisting of a GaInAsSb/AlGaAsSb quantum-well active region and AlGaAsSb cladding layers grown on GaSb substrates.

Abstract: A GaInAsSb quantum-well laser for highly efficient conversion of input energy to output infrared light is described. The laser consists of an MBE grown active region formed of a plurality of GaInAsSb quantum-well layers separated by AlGaAsSb barrier layers. The active region is sandwiched between AlGaAsSb cladding layers in which the Al content is greater than the Al content in the barrier layers.

Abstract: A strained quantum-well diode laser with an AlInGaAs active layer and AlGaAs cladding and/or confining layers on a GaAs substrate is provided. AlInGaAs/AlGaAs lasers can be configured in laser geometries including ridge, waveguide, buried heterostructure, oxide-defined, proton-defined, narrow-stripe, broad-stripe, coupled-stripe and linear arrays using any epitaxial growth technique. Broad-stripe devices were fabricated in graded-index separate confinement heterostructures, grown by organometallic vapor phase epitaxy on GaAs substrates, containing a single Al.sub.y In.sub.x Ga.sub.l-x-y As quantum well with x between 0.14 and 0.12 and y between 0.05 and 0.17. With increasing Al content, emission wavelengths from 890 to 785 nm were obtained. Threshold current densities, J.sub.th 's, less than 200 A cm.sup.-2 and differential quantum efficiencies in the range 71 to 88 percent were observed.

Abstract: Monolithic integration of Si MOSFETs and gallium arsenide MESFETs on a silicon substrate is described herein. Except for contact openings and final metallization, the Si MOSFETs are first fabricated on selected areas of a silicon wafer. CVD or sputtering is employed to cover the wafer with successive layers of SiO.sub.2 and Si.sub.3 N.sub.4 to protect the MOSFET structure during gallium arsenide epitaxy and subsequent MESFET processing. Gallium arsenide layers are then grown by MBE or MOCVD or VPE over the entire wafer. The gallium arsenide grown on the bare silicon is single crystal material while that on the nitride is polycrystalline. The polycrystalline gallium arsenide is etched away and MESFETs are fabricated in the single crystal regions by conventional processes. Next, the contact openings for the Si MOSFETs are etched through the Si.sub.3 N.sub.4 /SiO.sub.2 layers and final metallization is performed to complete the MOSFET fabrication.