High Voltage Silicon Carbide Devices

Abstract

Progress made in the development of high performance power rectifiers and switches from silicon carbide are reviewed with emphasis on approaching the 100-fold reduction in the specific on-resistance of the drift region when compared with silicon devices with the same breakdown voltage. The highlights are: (a) Recently completed measurements of impact ionization coefficients in SiC indicate an even higher Baliga's figure of merit than projected earlier. (b) The commonly reported negative temperature co-efficient for breakdown voltage in SiC devices has been shown to arise at defects, allaying concerns that this may be intrinsic to the material. (c) Based upon fundamental considerations, it has been found that Schottky rectifiers offer superior on-state voltage drop than P-i-N rectifiers for reverse blocking voltages below 3000 volts. (d) Nearly ideal breakdown voltage has been experimentally obtained for Schottky diodes using an argon implanted edge termination. (e) Planar ion-implanted junctions have been successfully fabricated using oxide as a mask with high breakdown voltage and low leakage currents by using a filed plate edge termination. (f) High inversion layer mobility has been experimentally demonstrated on both 6H and 4H-SiC by using a deposited oxide layer as gate dielectric. (g) A novel, high-voltage, normally-off, accumulation-channel, MOSFET has been proposed and demonstrated with 50x lower specific on-resistance than silicon devices in spite of using logic-level gate drive voltages. These results indicate that SiC based power devices could become commercially viable in the 21st century if cost barriers can be overcome.

Growth kinetics study in halide chemical vapor deposition of SiC

“…This is due to its high critical field for breakdown ($2 MV/cm) and high thermal conductivity ($5 W/cm K) [1][2][3][4][5]. Currently, two commercial growth methods are capable of high growth rates necessary for deposition of bulk crystals or very thick epitaxial layers for ultra high voltage devices.…”

SiC reversely switched dynistor (RSD) for pulse power application

“…Based on the advantage of the high insulation breakdown electric field, high intrinsic temperature and high thermal conductance of SiC [7] , SiC RSD could get higher blocking voltage for single chip, higher current density and better repetitive frequency performance hopefully.…”

Cross-polarization imaging and micro-raman detection of defects in the epitaxy of 4H-SiC

“…In addition, because it is an indirect gap material, SiC should have long minority carrier lifetimes, which play an important role in power devices. [1][2][3][4][5][6] However, SiC has many issues that must be resolved prior to insertion into real electronic systems. These include lower than expected minority carrier lifetimes (Ͻ1 µsec); 7,8 the formation of defects during bulk and epitaxial growth, and the formation and propagation of defects during device operation.…”