Barrier properties and current conduction mechanism for metal contacts to lightly and highly doped p-type 4H-SiC

Abstract

Abstract The barrier properties of Ti, Ni and Pt contact to lightly (9 × 1016 cm−3) and highly (9 × 1018 cm−3) doped p-type 4H-SiC were investigated. It is found that the barrier heights and ideality factors estimated from the thermionic emission model for the lightly doped samples are non-ideal and abnormally temperature dependent. The anomalies have been successfully explained in terms of both the pinch-off model and the Gaussian distribution of inhomogeneous barrier heights. In addition, the evaluated homogeneous barrier heights are reasonably close to the average barrier heights from capacitance–voltage measurements. For the highly doped samples, thermionic field emission (TFE) is found to be the dominant carrier transport mechanism. The barrier heights estimated from the TFE model are temperature independent. If the barrier inhomogeneities and tunneling effects are considered, the experimental results of the samples are in well agreement with the theoretical calculations.