ABSTRACT
The performance of Au I n-type GaN Schottky contacts is strongly dependent on the GaN surface processing prior to contacting. Current-voltage and electron beam induced current (EBIC) line scans demonstrate that KOH treatment acts to degrade the Schottky contacts. EBIC imaging reveals the differing sub-grain boundary structures of molecular beam epitaxy and etalorganic chemical vapour deposition grown GaN I sapphire. The KOH treatment acts to uniformly change the properties of the GaN surface, rather than having a localised effect. Metal contacts to GaN still represent one of the strongest limitations to the performance of GaN based devices. It is clear that the quality and the surface processing of the GaN also have a dominant effect on the resultant contact properties. Both the current-voltage data and the differences in the collection efficiency of the EBIC induced signals demonstrate that the KOH treatment of the GaN surface prior to metal deposition significantly degrades the Schottky contact.
