Studies of piezoelectric effects in [111] oriented strained Ga1−x In x Sb/GaSb quantum wells

Magnetotransport and optical measurements have been performed on two-dimensional hole gases confined in [001] and piezoelectrically active [111] oriented strained Ga_1−xIn_xSb/GaSb quantum wells. Comparison between simultaneously grown [001], [111]A, and [111]B structures reveals carrier density enhancement for the <111> growth direction and 50–70 meV Stark energy shifts which are well accounted for by the estimated piezoelectric field, of order 1 × 10⁵ V/cm. Double wells and superlattices were also investigated by inter-band magneto-optical experiments. The energy gap between the symmetric and anti-symmetric states is found to decrease with increasing indium content in double well structures.