Ohmic contact formation mechanism of Ni on n-type 4H-SiC

Abstract

Ohmic contact formation mechanism of Ni on n-type 4H-SiC is proposed by comparing the electrical properties with microstructural change. The ohmic behavior was observed at temperatures higher than 900 degreesC, but Ni2Si phase, as formerly reported to be responsible for ohmic contact, was formed after annealing at 600 degreesC. The higher work function of Ni2Si than Ni and the observation of graphite phase on the surface of Ni silicide after annealing at 950 degreesC support that a number of carbon vacancies were produced be-low the contact, playing a key role in forming an ohmic contact through the reduction of effective Schottky barrier height for the transport of electrons. (C) 2001 American Institute of Physics.