Optical and transport properties of piezoelectric [111]-oriented strained ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{In}}_{\mathit{x}}$Sb/GaSb quantum wells

Magneto-optical and magnetotransport studies have been conducted on a series of strained single ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{In}}_{\mathit{x}}$Sb/GaSb quantum wells grown along [001], [111]A, and [111]B directions by metal organic chemical vapor deposition. Both the interband transition energies and the two-dimensional carrier density show dramatic differences between the three orientations. Self-consistent calculations including the strain-induced piezoelectric field and the effect of band bending have been performed for the [111] structures. Results of the calculations agree very well with the observed dependences on indium content in the wells, well width, and cap thickness. The difference between [001] and [111] samples is due mainly to the presence of the piezoelectric field in the latter. The surface pinning field which is different in both direction and magnitude in the [111]A and [111]B structures contributes to the significant difference in these two orientations for cap thicknesses below 500 Å.