Schottky barrier formation at nonpolar Au/GaN epilayer interfaces

A new approach to studying Schottky barrier formation on a nanometer scale is demonstrated using both Auger electron spectroscopy core level shift and secondary electron threshold work function measurements on cleaved epilayers. Band bending induced by metallization of cleaved epilayer surfaces can be investigated without introducing defects due to chemical or ion beam surface cleaning. For GaN epilayers, this approach also avoids complications due to piezoelectric effects on polar-axis growth surfaces. Initial investigations of Au and Ag Schottky contact formation on GaN in ultrahigh vacuum reveal the presence of a pinning level ∼1.7 eV above the valence band edge.