Thermal stability of Pt Schottky contacts to 4H-SiC

Depth profiles by x-ray photoelectron spectroscopy have been used in conjun ction with current-voltage measurements to study the thermal stability of a 50-nm-thick Pt contact to n-4H-SiC substrate. A reaction between the Pt an d the SiC substrate is observed at temperatures of 600 degreesC and above. Annealing below that temperature improves the ideality and the uniformity o f the Schottky characteristics, while annealing above this temperature degr ades the electrical performance and uniformity. Thermodynamic stability is not reached even after annealing for 1 h at 900 degreesC. A local improveme nt of the characteristics at 800 degreesC is correlated with the formation of a second graphite film in the Pt-SiC reaction. (C) 2000 American Institu te of Physics. [S0021-8979(00)00523-5].