Effects of barrier height fluctuations and electron tunneling on the reverse characteristics of 6H–SiC Schottky contacts

Analytic calculations of electron transport across a Schottky barrier in 6H–silicon carbide are presented. The treatment includes the effect of barrier height fluctuations and image charge lowering on both the thermionic emission and electron tunneling processes. The results show that barrier height inhomogeneities are very important, and can lead to reverse current densities that are orders of magnitude higher than obtained from a simple theory. Formation of detrimental filamentary currents are predicted. The results are in very good agreement with published experimental data at 300 K. Finally, under forward biasing conditions, the analytical theory yields ideality factors of 1.037 in close agreement with measurements.