Reliability of 4H-SiC p-n Diodes on LPE Grown Layers

Abstract

In this paper we present for the first time the results from the long-term testing of power p-n diodes, grown on 4H-SiC substrates by liquid phase epitaxy (LPE). A comparison with 4H-SiC p-n diodes, made on commercially available chemical vapor deposition (CVD) p + pn o n + epitaxial wafers within the same device processing, is given. The increase of the forward voltage drop, DV F , as a function of the time for LPE and CVD diodes was observed. The striking feature was that the forward degradation in LPE diodes is expressed in less extent than the CVD ones. The observed lower degradation of the LPE diodes is explained by the lower recombination centers density (<10 13 cm -3 ) in LPE layers and consequently of the lower defects propagation when the diodes are subjected to a current load. At the same time, an increase of the specific on-state resistance is observed, which is explained by the presence of thin transition layer.

P-n Junction Periphery Protection of 4H-SiC Power p-i-n Diodes Using Epitaxy and Dry Etching

“…3. The foreword I F -V F characteristics of the described structure were given in [7]. These experimental results show that the proposed method is effective and more applicable one for protection of the junction edge of high voltage SiC diodes.…”

“…Two kinds of I R -V R characteristics were obtained for the structures, located on the same wafer -(a) such that are not influenced on the extended p layer (protective layer) thickness and (b) structures which I R -V R characteristics differ (improved) from vertical mesa design ones (p + layer edge is only vertically etched). As a rule, all diode structures of type (a) have bright points [7] and increased leakage current while bright points absent on the active regions of type (b) diodes. The bright points are increased recombination centers neutralizing the edge protection effect.…”