Mikihiko Shimura

Migration‐enhanced epitaxy on a (111)B oriented GaAs substrate

AlGaAs layers with a featureless specular surface morphology were grown successfully on an exactly (111)B oriented GaAs substrate by migration‐enhanced epitaxy (MEE) even at growth temperatures below 500 °C. We have also observed reflection high‐energy electron diffraction (RHEED) intensity oscillation of AlGaAs on a (111)B oriented substrate by MEE. The single quantum well (SQW) is prepared by MEE on a (111)B and a (100) substrate simultaneously, and the photoluminescence intensity from (111) SQW is shown to be about 50 times higher than that from (100) SQW.

Low‐temperature (350 °C) growth of AlGaAs/GaAs laser diode by migration enhanced epitaxy

Migration enhanced epitaxy, in which group III and group V elements are deposited onto the substrate alternately under ultrahigh vacuum, has been employed to reduce AlGaAs growth temperature. By optimizing growth conditions of AlGaAs, molecular‐beam intensities, and substrate temperatures between 600 and 250 °C, an AlGaAs/GaAs single‐quantum‐well laser diode has been fabricated successfully at very low temperature of 350 °C for the first time. A broad area laser diode emitting at 780 nm shows the threshold current density of 2.5 kA/cm2 at room temperature under the pulsed operation.

Low thermal expansion polymide buried ridge waveguide AlGaAs/GaAs single‐quantum‐well laser diode

A novel ridge waveguide laser diode has been developed in which the ridge is buried in a newly developed polyimide with a low thermal expansion coefficient close to that of AlGaAs which reduces the thermal stress to the junction and simplifies the wafer processing. A planar configuration, which is suitable for optoelectronic integration and an episide down mount for high‐power operation, has been achieved by an etch‐back process. Under cw operation, a low threshold current of 15 mA at 25 °C, a characteristic temperature T0 of 145 K, and maximum power output higher than 30 mW/facet have been obtained in a molecular‐beam‐epitaxial‐grown graded‐index separate confinement heterostructure single‐quantum‐well laser emitting at 780 nm.

GaAs double quantum well laser diode with short-period (AlGaAs)m(GaAs)n superlattice barriers

A short‐period (AlGaAs)m(GaAs)n superlattice has been applied to the barrier layers in a single and a multiple quantum well structure prepared by molecular beam epitaxy in order to improve the interface quality. With a 38 A thin GaAs quantum well without employing aluminum, a low threshold current density of 260 A/cm2, a high characteristic temperature (T0) of 205 K, and a high differential quantum efficiency of 75% have been achieved in a double quantum well ridge waveguide laser diode emitting at 780 nm.

Very Short Wavelength (621.4 nm) Room Temperature Pulsed Operation of InGaAsP Lasers

Page L488, Wrong Central R & D Laboratory OMRON Tateisi Electronics Co., 20 Igadera, Shimokaiinji, Nagaokakyo Niigata 617 Correct Central R & D Laboratory OMRON Tateisi Electronics Co., 20 Igadera, Shimokaiinji, Nagaokakyo 617

Liquid Phase Epitaxial Growth of lnGaAsP on GaAs1-yPy Substrates (y=0.31 and 0.39)

Lattice matched InGaAsP mixed crystals with various energy bandgaps were grown by liquid phase epitaxy (LPE) on GaAs1-yPy substrates (y=0.31 and 0.39). The growth layers had smooth and shiny surfaces with undulated morphology reflecting the cross-hatching pattern of GaAsP substrates. The influences of offset angle and crystal composition of the InGaAsP growth layer on the surface morphology of the InGaAsP growth layer were investigated. The offset angle was not the main cause of the undulated morphology in our experiments. Photoluminescence spectra and X-ray rocking curves of the growth layers were measured in order to determine their energy bandgaps and lattice constants. The doping characteristics of zinc and tellurium were also investigated. The growth conditions and properties of the InGaAsP layers on GaAsP substrates are described in detail.

Semiconductor laser digital scanner

A novel static semiconductor laser digital scanner is proposed and demonstrated. The scanner consists of a monolithically integrated semiconductor laser array and an aspheric convex lens. Laser beams are deflected and scanned digitally by the convex lens with no mechanical action. Extremely high scanning speed can be achieved with this scanner because the scanning speed is in principle limited only by semiconductor laser switching time. Scanning angles of the laser beam up to 400 were obtained for a 10-element semiconductor laser array. The array spacing is 300 p.m. and an aspheric convex lens with 4.5 mm focal length was used. Intensity profiles of the deflected beam coincide with calculations using the ray tracing method.

High-efficiency AlGaAs/GaAs single-quantum-well semiconductor laser with strained superlattice buffer layer

The use of a strained superlattice buffer (SSLB) layer composed of a short-period (InGaAs)(GaAs) superlattice in a lattice-matched AlGaAs/GaAs system in order to reduce the internal stress is discussed. A five-times-higher photoluminescence peak intensity has been observed from a single quantum well (SQW) with the SSLB than without the SSLB. A high-quantum efficiency, a small cavity loss, and high-output power operation have been achieved in a narrow ridge-waveguide 770-nm graded-index-separate confinement heterostructure SQW laser diode with the SSLB.<<ETX>>

CW Lasing Characteristics of Visible InGaAsP Lasers Grown on GaAsP Substrates

Continuous wave operation of visible-light emitting InGaAsP injection lasers grown on GaAs0.61P0.39 substrates by liquid phase epitaxy was obtained in the temperature range of 98?197 K. Their lasing wavelength was 630 nm at 197 K. The characteristic temperature T0 was estimated to be 58 K.

LPE Growth of Lattice-Matched InGaAsP on GaAs0.69P0.31 Substrates and Low Threshold Current Density Operation of Visible InGaAsP DH Lasers

Lattice-matched InGaAsP epitaxial layers with various energy band gaps (Eg=1.874–2.115 eV) have been grown on (100)GaAs0.69P0.31 substrates by a ramp cooling liquid phase epitaxial (LPE) method. Energy band gaps and crystal compositions were determined by photoluminescence and double-crystal X-ray diffraction. Double-heterostructures were successfully grown and lased under a pulsed condition with low threshold current density (Jth=2.21 kA/cm2) and short wavelength (λp=659 nm) at room temperature. The highest external quantum efficiency was 21.7%/facet.