The improvement of ohmic contact of Ti/Al/Ni/Au to AlGaN/GaN HEMT by multi-step annealing method

Abstract

A multi-step rapid thermal annealing process of Ti/Al/Ni/Au was investigated for ohmic contact of AlGaN/GaN high electron mobility transistor(HEMT).The samples were studied by Transmission Line Model(TLM),Scanning Electron Microscopy(SEM) and Auger Electron Spectroscopy(AES) measurements. By the multi-step annealing process, the specific contact resistance was decreased and the surface morphology was improved. The AES measurements showed that the limitation indiffusion of Au and outdiffusion of Al were account for the surface morphology improvement.