Thickness variations in GaAs/AlGaAs quantum wells grown on patterned substrates by molecular beam epitaxy have been analyzed by spatially and spectrally resolved low-temperature cathodoluminescence. For the lower and upper (100) facets joined by an angled (311)A facet, relative increases in quantum well thicknesses up to ≂6% and 20% are observed, respectively, in the vicinity of the intersection of the facets. Following an exponential behavior, the Ga adatom migration length is found to be in the range of 1–2 μm on both the lower and upper (100) facets and is independent of quantum well thickness. This migration length is orders of magnitude greater than previously reported for Ga adatoms during molecular beam epitaxy growth.

GaAs/AlGaAs quantum wells (QWs) were grown by molecular beam epitaxy on GaAs (100) substrates patterned with ridges and grooves in the [011̄] direction. Low-temperature cathodoluminescence was used to measure the Al fraction and QW thickness on top of the ridges and grooves as a function of ridge and groove width. Surface diffusion during growth depletes Ga from the side facets while increasing the incorporation of Ga on the (100) sections of ridges and grooves. The QW thickness on top of a ridge grown at 710 °C increases from 72 to 95 Å, and the Al fraction x decreases from x=0.33 to x=0.29 as the ridge width is narrowed from 30 to 4 μm. Graded refractive index separate confinement heterostructure lasers with nominally 70 Å QWs and Al0.2Ga0.8As barriers were grown on patterned substrates at 695 and 725 °C. Lasers fabricated on the overgrown 4-μm-wide ridges have a 20 meV decrease in emission energy compared to laser diodes on 30 μm ridges.

We demonstrate a high-power AlGaAs single quantum well graded-index separate confinement heterojunction laser grown by molecular epitaxy over channeled substrates. Fundamental mode operation up to 130 mW for reflection modified devices has been achieved at a high differential quantum front-facet efficiency of 81%. This device structure allows extremely low threshold currents to 6 mA for power lasers due to the incorporation of lateral current blocking pn junction by crystallographic plane-dependent doping of amphoteric dopants. We obtained a very high-power continuous-wave fundamental mode operation of this type of laser at extremely low threshold currents and very high overall efficiency of more than 50%. This laser shows considerable potential for applications in optical storage and printer technology.

Strainedlayer InGaAsGaAsAlGaAs gradedindex separate confinement heterostructure single quantum well lasers grown by molecular beam epitaxy Appl.Lowthreshold interruptedgrowth stepindex separateconfinement heterostructure GaAs/(Al,Ga)As lasers grown by molecularbeam epitaxy

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