Al/Ti/4H–SiC Schottky barrier diodes with inhomogeneous barrier heights

This paper investigates the current--voltage (I--V) characteristics of Al/Ti/4H--SiC Schottky barrier diodes (SBDs) in the temperature range of 77 K--500 K, which shows that Al/Ti/4H--SiC SBDs have good rectifying behaviour. An abnormal behaviour, in which the zero bias barrier height decreases while the ideality factor increases with decreasing temperature (T), has been successfully interpreted by using thermionic emission theory with Gaussian distribution of the barrier heights due to the inhomogeneous barrier height at the Al/Ti/4H--SiC interface. The effective Richardson constant A^*=154 A/cm^2 \cdot K^2 is determined by means of a modified Richardson plot \ln(I_0/T^2)-(q\sigma )^2/2(kT)^2 versus q/kT, which is very close to the theoretical value 146~A/cm^2 \cdot K^2.