[001]- and piezoelectric-[111]-oriented InAs/GaSb structures under hydrostatic pressure

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Abstract
Magnetotransport measurements have been carried out under hydrostatic pressure on [001]- and [111]-oriented InAs/GaSb structures grown by metal-organic vapor-phase epitaxy. The system is semimetallic at zero pressure, but as the pressure is increased, electrons, located in the InAs layers, transfer back into the valence band of GaSb and a semimetal-to-semiconductor transition is observed. In double heterojunctions the zero band overlap condition occurs at 14 and 17 kbar for the [001] and [111] A orientations, respectively. The band crossing at the interface has been calculated self-consistently for the two orientations, taking into account the intrinsic and extrinsic origins of the carriers. This band overlap is found not only to be strongly orientation dependent, approximately 60 meV larger in [111] A compared with [001], but also to decrease at rates of 10 and 12 meV/kbar for the [001] and [111]A orientations, respectively. These rates are much larger than those determined from molecular beam epitaxy samples, but closer to the variation with pressure of the band gaps of the bulk materials.