The Physics of Ohmic Contacts to SiC

Abstract

The specific contact resistance of an ohmic contact will be discussed including ways to calculate and measure this parameter. Ohmic contacts to n- and p-type hexagonal SiC will then be detailed. Low resistance n-type ohmic contacts are predominately fabricated by annealing a refractory metal, thereby forming a silicide with a lowered Schottky barrier height at the metal–SiC interface. P-type contacts on the other hand generally use Al or Al alloys which upon annealing enable Al to diffuse into the SiC thus resulting in ohmic properties. Aluminium alloys however suffer from many problems which will be discussed. Other novel contacting schemes to p-type SiC will also be reviewed.