Thermal stability of Re Schottky contacts to 6H-SiC

The thermal stability of a 100-nm thick sputter-deposited Re film as contact to 6H-SiC was studied by backscattering spectrometry and by measurements of the forward current-voltage (I-V) characteristic. The initial Schottky barrier height of 0.71 eV and ideality factor of 1.6 change after 2 h of annealing in vacuum at 700 degreesC to 1.04 eV and 1.1, respectively. They remain stable after annealing for additional 2 h at that same temperature. The initial change is attributed to a recovery of sputter damage in the SiC, The observed stability of the Schottky barrier is attributed to the thermodynamic stability of Re with SiC, as confirmed by the unchanging backscattering depth profiles. After annealing at 900 degreesC, the Schottky barrier becomes unstable although no interaction between the Re film and the SiC substrate is detectable in the depth profiles.