Effects of substrate misorientation and background impurities on electron transport in molecular-beam-epitaxial-grown GaAs/AlGaAs modulation-doped quantum-well structures
- 1 August 1987
- journal article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 62 (3) , 954-960
- https://doi.org/10.1063/1.339707
Abstract
Single GaAs quantum wells, clad with Al0.3Ga0.7As, and modulation doped with silicon introduced in the Al0.3Ga0.7As after the quantum wells are grown have been grown by molecular-beam epitaxy on GaAs substrates tilted a few degrees from the nominal (001) plane towards either of the (111) planes. The low-field two-dimensional electron gas mobility is observed to be a function of the tilt angle (0°, 2°, 4°, 6.5°) and of the direction of tilt [towards (111)A or (111)B]. The two-dimensional electron gas mobilities in quantum-well structures grown on substrates tilted towards (111)A are larger than those in structures grown on nominally flat (001) substrates. The improvement in two-dimensional electron gas transport is attributed to an improvement in the quality of the inverted interface (i.e., GaAs grown on AlGaAs). Quantum wells grown on substrates tilted toward (111)A also exhibit larger two-dimensional electron gas mobilities than quantum wells grown on substrates tilted toward (111)B for a given angle of tilt. For quantum-well structures where interface scattering from the inverted interface is significant, the two-dimensional electron gas mobility is observed to be anisotropic and larger in the [110] direction in comparison to the [1̄10] direction. The anisotropy in electron transport in the GaAs quantum well is observed to be larger for structures where the substrate tilt is towards (111)B in comparison to (111)A. For quantum wells grown on substrates tilted toward (111)A the anisotropy in two-dimensional electron gas mobility gets progressively larger as the tilt angle gets smaller. Larger molecular-beam epitaxy machine background impurity concentrations are observed to significantly increase the magnitude of the anisotropy in two-dimensional electron gas mobility suggesting that impurities and/or defects introduced during MBE growth are the origin of the anisotropic transport.This publication has 23 references indexed in Scilit:
- Structural changes of the interface, enhanced interface incorporation of acceptors, and luminescence efficiency degradation in GaAs quantum wells grown by molecular beam epitaxy upon growth interruptionJournal of Vacuum Science & Technology B, 1986
- GaAs/Ga1−xAlxAs and Ga1−xAlxAs/GaAs heterointerfaces grown by molecular beam epitaxySurface Science, 1986
- Properties of AlxGa1−xAs (xAl≂0.3) grown by molecular-beam epitaxy on misoriented substratesJournal of Applied Physics, 1986
- Atomic-Scale Structures of Top and Bottom Heterointerfaces in GaAs–AlxGa1-xAs (x=0.2-1) Quantum Wells Prepared by Molecular Beam Epitaxy with Growth InterruptionJapanese Journal of Applied Physics, 1986
- Optical studies of impurity trapping at the GaAlAs/GaAs interface in quantum well structuresJournal of Applied Physics, 1985
- Investigation of surface roughness of molecular beam epitaxy Ga1−xAlxAs layers and its consequences on GaAs/Ga1−xAlxAs heterostructuresJournal of Vacuum Science & Technology B, 1985
- Improvement of the inverted GaAs/AlGaAs heterointerfaceJournal of Vacuum Science & Technology B, 1984
- Impurity trapping, interface structure, and luminescence of GaAs quantum wells grown by molecular beam epitaxyApplied Physics Letters, 1984
- Effect of substrate annealing and V: III flux ratio on the molecular beam epitaxial growth of AlGaAs-GaAs single quantum wellsJournal of Electronic Materials, 1983
- Dependence of the structural and optical properties of GaAs-Ga1−xAlxAs multiquantum-well structures on growth temperatureApplied Physics Letters, 1981