Thermal Stability of Ohmic Contacts to n-InxGa1−xN

Abstract

ABSTRACTThe microstructural properties and interdiffusion reactions of Au/Ge/Ni, Ti/Pt/Au, WSix and AuBe contacts on GaN and In0.5Ga0.5N have been examined using Scanning Electron Microscopy and Auger Electron Spectroscopy. The WSix contacts possess excellent thermal stability and retained good structural properties at annealing temperatures as high as 800°C on GaN. The electrical characteristics of WSix contacts on In0.5Ga0.5N had a specific contact resistivity of 1.48×10−5Ωcm2 and an excellent surface morphology following annealing at 700°C. The increase in contact resistance observed at higher temperatures was attributed to intermixing of metal and semiconductor. In contrast the Ti/Pt/Au and Au/Ge/Ni contacts were stable only to ≤ 500°C. AuBe contacts had the poorest thermal stability, with substantial reaction with GaN occurring even at 400°C. The WSix contact appears to be an excellent choice for high temperature GaN electronics applications.