Summary Abstract: Valence-band Discontinuities in (100) GaSb/AlSb and GaSb/InAs Heterojunctions.

X-ray photoemission core level measurements have been used to determine the valence-band discontinuity DELTA E sub v in (100)-oriented GaSb/AlSb and GaSb/InAs strained-layer heterojunctions. For GaSb/AlSb, we find DELTA E sub v = 0.41 +1 0.1 eV or wig 0.27 DELTA E sub g, indicating that the band lineup is similar to GaAs/AlAs. The large value of DELTA E sub v demonstrates that the common anion rule is incorrect for predicting the band alignment in this system. For GaSb/InAs the valence-band discontinuity is 0.51 +- 0.1 eV, which shows that the band lineup is of the broken-gap variety and places the InAs conduction band 150 meV lower in energy than the GaSb valence band. The same valence-band discontinuity is observed (within 50 meV) independent of growth sequence for both heterojunction systems.