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

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, DeltaV(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.