4,308V, 20.9 mΩ-cm<sup>2</sup> 4H-SiC MPS Diodes Based on a 30μm Drift Layer

Abstract

This paper reports the design, fabrication and characterization of high voltage 4H -SiC merged PiN/Schottky-barrier (MPS) diodes with an active area of 1.4mm 2 . For comparison purposes, Schottky barrier, PiN and MPS diodes of smaller size (8.1x10 -2 mm 2 ) have also been designed and fabricated on the same wafer with a 30 µm, n=2x10 15 cm -3 doped drift layer. The Schottky spacing between the adjacent p+ regions in the MPS diodes has been designed to be 7, 8, 9, and 10µm so that the trade-off between the forward current capability and the reverse leakage current can be investigated. A multi-step junction termination extension (MJTE) structure is utilized to terminate the device edge because it is capable of providing a near theoretical breakdown voltage. MPS diodes have achieved similar breakdown voltages to that of the PiN diodes while providing a forward current close to that of SBDs. MPS diodes have also shown reliable avalanche operations with avalanche breakdown voltage up to 4,308V , limited only by the SiC critical field. One of the best MPS diode achieves a blocking voltage (V B) of 4,308V and conducts a forward current density of 142 A/cm 2 at a forward voltage drop (VF) of 4V with a differential specific on- resistance (RSP_ON) of 20.9 mO·cm 2 , yielding a V B 2 /RSP_ON of 888 MW/cm 2 , which is among the highest figure-of-merit (FOM) reported to date.