Determination of the (100) InAs/GaSb heterojunction valence-band discontinuity by x-ray photoemission core level spectroscopy

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Abstract
The valence-band discontinuity ΔEv has been determined for the (100) InAs/GaSb system by x-ray photoemission core level spectroscopy. For 20 Å of InAs on GaSb we find that ΔEv=0.53 eV. The reverse structure, consisting of a 20-Å layer of GaSb on InAs, gave a measured value of ΔEv=0.48 eV. Since the difference in these two values lies within our experimental uncertainty, we report an average offset of 0.51±0.1 eV. The large value of the valence-band discontinuity in this system shows the band lineup to be of the broken gap variety with the InAs conduction-band energy lying below that of the GaSb valence band. This result is in good agreement with theoretical predictions.