Thermal stability of multilayer contacts on gallium nitride

The results of investigation of a new system of metallization for nonrectifying contacts on n-GaN are presented. The new contact metallization system involves the following sequence of layers: Au(200 nm)-Ti(TiBx)(100 nm)-Al(20 nm)-Ti(50 nm), where the TiBx layer plays the role of a diffusion barrier. The contacts with the TiBx layer retain their layer structure and electrical characteristics upon annealing up to 700 degrees C, whereas the usual Au-Ti-Al-Ti structure exhibits degradation upon rapid thermal annealing at T = 700 degrees C. Further increase in the annealing temperature to 900 degrees C leads to smearing of the layer structure of the Au-TiBx-Al-Ti-GaN contact. Physical factors responsible for the change in the parameters of such contact systems are considered. (C) 2005 Pleiades Publishing, Inc.