Determination of the (100) InAs/GaSb heterojunction valencehyphen;band discontinuity by xhyphen;ray photoemission core level spectroscopy

摘要

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