Optimising the rectification ratio of schottky diodes in n-SiC and n-Si by TCAD

Finite element modelling has been used to optimise the current/ voltage (I/V) characteristics of metal/ n-SiC and metal/ n-Si diodes incorporating a thin interfacial layer. The electrical properties of the diodes have been examined in relation to the polytype of SiC (3H, 4H or 6C), the doping level, NA, (1015 - 1018cm3) of the substrate, the defect state density, Dit and the work function of the Schottky metal, Φm. The modelling by Technology Computer-Aided Design (TCAD) has shown that the presence of an interfacial insulating layer with a thickness of 1.0 nm has reduced the reverse leakage current of the diode by a factor of ∼102 in Si and 1013 (from 10-19 A to 10-6 A) for SiC with only a minor reduction (∼ 0.8 times) in the forward current in SiC. The properties of the diodes have been modelled at room temperature without thermal annealing.