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

Low-temperature magnetotransport measurements on Ga Sb ∕ In As ∕ Al Sb 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 width is greater than around 900 Å . For smaller GaSb cap widths, E FS decreases with the GaSb width. The undoped Ga Sb ∕ In As ∕ Al Sb heterostructure's Fermi level is determined by bulk donor defects in the AlSb layer adjacent to the InAs quantum well.