Extremely Flat Interfaces in GaAs/AlGaAs Quantum Wells Grown on GaAs (411)A Substrates by Molecular Beam Epitaxy

Abstract

GaAs/Al0.3Ga0.7As quantum wells (QWs) grown on (411)A-oriented GaAs substrates by molecular beam epitaxy (MBE) showed extremely flat interfaces over a macroscopic area (about 200 µm φ) even for the case of no growth interruption, which is mainly due to the intrinsically large migration of Ga atoms and layer growth in the step-flow mode on the (411)A plane. Photoluminescence linewidths at 4.2K were almost the same as or better than the narrowest linewidths reported for GaAs/AlGaAs and GaAs/AlAs QWs grown on GaAs (100) substrates with growth interruption at each GaAs/AlGaAs(AlAs) interface. Only one sharp luminescence peak was observed for each QW on the (411)A substrates, in contrast with three luminescence peaks for the QWs on the (100) substrates, indicating that extremely flat and uniform interfaces over a macroscopic area of laser excitation (200 µm diameter) are realized in the GaAs/AlGaAs QWs grown on (411)A GaAs substrates.

Surface segregation of indium atoms during molecular beam epitaxy of InGaAs/GaAs superlattices on GaAs substrates

“…For example, we have reported that effectively atomically flat interfaces over a macroscopic area (''super-flat interfaces'') can be formed in GaAs/AlGaAs and pseudomorphic InGaAs/AlGaAs quantum wells (QWs) grown on (4 1 1)A-oriented GaAs substrates by molecular beam epitaxy (MBE) [1][2][3][4].…”

Atomic Structure of the Stoichiometric GaAs(114) Surface

“…Under As-rich preparation conditions the surface revealed an atomically rough structure, whose reconstruction model was derived from reconstructions known for the GaAs(001) surface [19,[22][23][24]. However, under Ga-rich conditions a transition to an extremely flat surface has been reported [24,25].…”

“…Because of its similarity to (001), the GaAs(114) surface has been considered in early studies of heterostructures as a highly vicinal GaAs(001) surface, whose terraces extend only over a single b͑2 3 4͒-unit cell [19,20]. Moreover, this stepped morphology led to the assumption that this surface should be predestinated to accommodate strain in heterostructures [21].…”

As 4 pressure dependence of surface segregation of indium atoms during molecular beam epitaxy of In0.08Ga0.92As/GaAs superlattices on (411)A GaAs substrates

“…5 The In surface segregation has a large influence on the quantization energy level in the QW, which was studied by secondary ion mass spectroscopy and lowtemperature photoluminescence ͑PL͒ measurements. 6,7 Recently, we reported that effectively atomically flat interfaces over a wafer-size area ͓(411)A super-flat interfaces͔ can be formed not only in GaAs/AlGaAs QWs 8,9 but also in pseudomorphic In x Ga 1Ϫx As/Al 0.3 Ga 0.7 As QWs (xϭ0 -0.15) 10,11 grown on (411)A GaAs substrates by MBE. The formation of the (411)A superflat interfaces is strongly correlated with much enhanced surface migration of group III atoms on the (411)A plane compared with that on the ͑100͒ plane, because flatness of heterointerfaces in the (411)A GaAs/ AlGaAs QWs degrades under high As 4 pressure, 12 where surface migration of group III atoms is suppressed.…”