Stability of W and Re contacts to GaN

The thermal stability of W and Re metal contacts to GaN upon vacuum thermal annealing at 600, 800 and 1000/spl deg/C for 30 min is investigated by means of 2.0 MeV He/sup ++/ backscattering spectrometry, X-ray diffractometry and scanning electron microscopy. No reaction with GaN could be detected for either W or Re after any time-temperature cycle applied. The instability induced by the dissociation of GaN imposes an upper practical limit for the duration of vacuum heat treatment of tungsten or rhenium metal contacts to GaN of about 30 min at 800/spl deg/C.