Numerical Simulation of P-Type Al/4H-SiC Schottky Barrier diodes

Abstract

Wide-bandgap (WBG) power semiconductor devices have good potential to replace Silicon-based devices for operating at higher temperatures. Silicon carbide (SiC) currently represents an established WBG candidate for developing power Schottky barrier diodes (SBD) used in power electronics that are required for the next generation power devices. Very few information is available about P-type 4H-SiC substrate being used for realization of SBD. Pre-production Technological computer aided design (TCAD) simulation of SBD, where p-doped epitaxial layer on p-type 4H-SiC substrate corresponds to experimental structures (currently in manufacturing process) could generate defects under the contact. P-type SiC SBD with some defects types is also examined for evaluating the influence on the forward current and reverse voltage blocking. Forward and reverse bias static characteristics are obtained for p-type 4H-SiC SBD at temperatures in the range of 300K to 600K. The currents are shown to have a large on resistance and tunneling component depending on the defects. The SBD device simulation shows that there is significant impact on the reverse current and voltage despite of the very thin defective layer. The reverse breakdown voltages of the diodes were found to decrease from several hundred volts to -100 V indicating the presence of defects edge leakage currents. The structural properties and characteristics of the resulting defects in the schottky contact layer are discussed.