Reverse Leakage Currents in High-Voltage 4H-SiC Schottky Diodes

High-voltage 4H-SiC Schottky Barrier Diodes (SBDs) and Junction Barrier Schottky (JBS) diodes have been fabricated and evaluated. Current-voltage (I-V) characteristics were measured in a wide temperature range. All diodes fabricated showed nearly ideal forward behavior. For SBDs with Schottky Barrier Height (SBH) of 1.12 eV, the reverse I–V characteristics are described well by the thermionic emission model (at voltages varying from several mV to 2 kV and temperatures ranging from 361 to 470 K) if barrier lowering with increasing band bending is taken into account. For SBDs with SBH of 1.53 eV, no thermionic current was detected in reverse direction at temperatures below ~500 K. The leakage currents appeared only at high reverse voltages and elevated temperatures. The analysis of reverse I-V characteristics allowed to propose dislocation related mechanism of current flow due to the local injection of electrons from metal to semiconductor. It is shown that defect related leakage currents can be significantly reduced by JBS-structure.