Electrical and structural characterization of a single GaSb∕InAs∕GaSb quantum well grown on GaAs using interface misfit dislocations

Abstract

Interface misfit formation has been used for the growth of high mobility GaSb∕InAs single quantum wells (SQW) formed on GaAs substrates. The SQW structure was topped with 800Å GaSb, followed by 100Å GaSb:Si (5×108cm−3), 10nm GaSb, 10nm InAs, and finally 250nm GaSb on a GaAs substrate. The structural quality was examined using high resolution x-ray diffraction and transmission electron microscopy. Reciprocal space mapping indicated that the GaSb was completely relaxed. A high resolution x-ray rocking curve showed good agreement between the proposed structure and the simulation, assuming that all layers were relaxed to the GaSb lattice, and clearly showed interference fringing from individual layers. Atomic force microscopy showed the film appeared textured, and that the final growth occurred by step flow growth. The observed peak-to-peak roughness was 7nm over a 100×100μm2 square area. Plane view transmission electron microscopy analysis showed a nearly regular array of Lomer dislocations responsible for the relaxation of the strain in the two films. The mobility of the SQW was measured as a function of temperature. The room temperature mobility was 13900cm2∕Vs and a peak mobility of 25200cm2∕Vs was observed at ∼60K, and remained nearly constant at lower temperatures. The sheet concentration was 2.3×1012∕cm2 at room temperature, and dropped to 7.35×1011∕cm2 at 60K. Magnetoresistance measurements revealed the presence of Shubnikov–de Haas oscillations at 1.2K; indicating the presence of a good quality two-dimensional electron gas (2DEG). Further support for the high quality of the 2DEG is provided by the observation of sharply defined quantum Hall plateaus.