Cross-sectional scanning photoelectron microscopy and spectroscopy of wurtzite InN∕GaN heterojunction: Measurement of 'intrinsic' band lineup

A method for studying heterojunction band lineups on the submicrometer scale is demonstrated by using synchrotron-radiation photoelectron microscopy and spectroscopy. In particular, an in situ sample cleavage technique is adopted here to reveal the cross-sectional, nonpolar a-plane face of InN∕GaN heterojunction grown on Si(111) along the polar −c axis with fully relaxed lattice structure, eliminating the polarization effects associated with the interface charge/dipole normal to the cleaved surface. The “intrinsic” valence band offset at the cleaved InN∕GaN heterojunction has been determined to be 0.78eV. Additionally, using known material parameters, the values of InN∕GaN conduction band offset and InN electron affinity are also estimated.