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

Low-temperature magnetotransport measurements on GaSbInAsAlSb 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, EFS, of undoped molecular-beam-epitaxy-grown GaSb. EFS is pinned around 0.2 eV above the top of the GaSb valence band when the GaSb cap layer width is greater than around 900 Å. For smaller GaSb cap widths, EFS decreases with the GaSb width. The undoped GaSbInAsAlSb heterostructure's Fermi level is determined by bulk donor defects in the AlSb layer adjacent to the InAs quantum well.