Piezoelectric effects in superlattices
Magnetotransport and optical measurements have been carried out on (001) and piezoelectrically active (111) InGaSb/GaSb and InAs/GaSb structures. In accordance with theory, these comparative studies reveal enhanced carrier density and mobility for growth in the (111) direction. The observed Stark shifts of up to 100 meV, in the (111) oriented InGaSb/GaSb structures are well accounted for by the estimated built-in piezoelectric field, of the order of 1*105 V cm-1. The absorption coefficient of (111) oriented InAs/GaSb superlattices shows significant enhancement.