Measurement of the GaSb surface band bending potential from the magnetotransport characteristics of GaSb-InAs-AlSb quantum wells

Low-temperature magnetotransport measurements on GaSb/InAs/AlSb coupled quantum well structures with a GaSb cap layer and self-consistent calculations of their electronic structure have led to the determination of the Fermi level at the surface, E$_{FS}$, of undoped molecular-beam-epitaxy-grown GaSb. E$_{FS}$ is pinned around 0.2 eV above the top of the GaSb valence band when the GaSb cap layer is width is greater than 900 {\AA}. For smaller GaSb cap widths, E$_{FS}$ decreases with the GaSb width. The heterostructures' Fermi level is determined by bulk donor defects in the AlSb layer adjacent to the InAs quantum well.