Optimisation of junction termination extension for the development of a 2000 V planar 4H-SiC diode

The device structure of a 2 kV 4H-SiC P+NN+ planar diode with different edge terminations is optimised with simulation results. Since the periphery protection is a key issue in the design of Silicon carbide (SiC) power diodes, several techniques such as single- and double-junction termination extension (JTE) and a combination of JTE and guard rings (GRs) have been studied. The MEDICI simulator has been used, including specific parameters for 4H-SiC. In the single implanted zone JTE, the breakdown is strongly dependent upon the dose of dopants introduced into the edge region. We find that a depletion of the surface doping effectively reduces the surface electric field up to 40%. To widen the range of optimum JTE parameters keeping technological simplicity in mind, we have studied the behaviour of double JTE structures. Another investigated periphery protection, consist to form a series of GRs embedded in a JTE structure, with this protection the diode achieves more ideal efficiency of breakdown capabilities. (C) 2002 Elsevier Science B.V. All rights reserved.