Magnetotransport measurements on InAs-GaSb quantum wells with the application of hydrostatic pressure

Abstract We present a series of magnetotransport measurements on high mobility single InAs-GaSb semimetallic quantum wells using hydrostatic pressures up to 10 kbar and temperatures down to ~100mK. Clearly defined, hole-related peaks in pϱ xx close to integer electronic filling factors in the semimetallic regime, have a stronger temperature dependence than the electron Shubnikov-de Haas effect at millikelvin temperatures and with this additional structure, apparent in ϱ xx the quantum Hall plateaux in ϱ xy deviate from h ve 2 , where v is the filling factor. The decrease in the electron concentration, dn 0 dp is 3.0 × 10 10 cm −2 kbar −1 in the dark, and 4.0 × 10 10 cm −2 kbar −1 in the dark following infrared illumination to reduce the Fermi energy. We relate this reduction in the electron and hole concentrations to the uncrossing of the InAs conduction band and the GaSb valence band and to the role played by a GaSb surface donor at high pressures. The fermi energy at the surface is pinned approximately 250 meV above the GaSb valence band edge.