Reduction of surface defects in GaAs grown by molecular beam epitaxy

Abstract

A method to reduce the density of oval defects originating from pregrowth surface particulates and other contaminants for GaAs layers grown by molecular beam epitaxy (MBE) is presented. It appears that if a thin GaAs buffer layer is deposited by alternately supplying Ga atoms and As4 molecules to a GaAs substrate, prior to further growth by MBE, the density of the oval defects in the final layer is reduced reproducibly by a factor of 7, from about 490 to 70 cm−2, when compared with that obtained using MBE alone under closely similar conditions. The improved surface morphology produced by the pulsed beam method is thought to be related to initial film growth which proceeds likely in a two-dimensional layer-by-layer fashion.

Molecular Beam Epitaxy of High-Quality GaAs and AlGaAs

“…gallium agglomeration from an increased population of gallium on the surface. The oval defect density is reduced from -490 cm 2 to ~ 70 cm -2 if the initial 50-200 nm thick GaAs buffer layer is grown by migration-enhanced epitaxy (MEE) at low temperatures (300~ [436] (MEE is similar to MBE except that the group III and group V fluxes are supplied alternately, resulting in the growth of one epitaxial layer each cycle.) [139][313] [432] The dimeric arsenic may reduce either the gallium surface population[ ~39] or the gallium surface mobility, thus preventing gallium agglomeration and oval defect formation.…”

High-peak-power low-threshold AlGaAs/GaAs stripe laser diodes on Si substrates grown by migration-enhanced molecular beam epitaxy

“…3 Ga o . 7 As cladding layer, a 0.1----0,2 p.m undoped GaAs active layer, a 1.5 f.lill Mgdoped (1 X 10 18 cm -3) Al o ,} Ga o . 7 As dadding layer, and a 0.2-0.3 pm Mg-doped (5 X 10 18 cm-l ) GaAs cap layer.…”

“…7 As cladding layer, a 0.1----0,2 p.m undoped GaAs active layer, a 1.5 f.lill Mgdoped (1 X 10 18 cm -3) Al o ,} Ga o . 7 As dadding layer, and a 0.2-0.3 pm Mg-doped (5 X 10 18 cm-l ) GaAs cap layer. The 6 !-lm oxide stripe laser diodes were fabricated on the AIGaAs/GaAs double heterostructure directly grown on Si substrates.…”