Characterization of leakage current on diamond Schottky barrier diodes using thermionic-field emission modeling

A diamond vertical Schottky barrier diode (SBD) with nonepitaxial crystallites (NCs) exhibits high leakage current in both its forward and its reverse characteristics. A shunt path current through the grain boundary of the NCs is the dominant mechanism. The defectless device shows a low leakage current of less than 10^− 11 A/cm², and the device yield corresponds to the density of the NCs. The reverse leakage current of the defectless device increases with the reverse field. The leakage current of the diamond SBD is in good agreement with the tunneling model described by thermionic-field emission (TFE) rather than the conventionally used barrier-lowering model. The TFE current dominates when the reverse electric field is larger than 1.2 MV/cm, and current density reaches 10^− 6 A/cm², even at 1.6 MV/cm, which is lower than the avalanche limit.