Material quality improvements for high voltage 4H-SiC diodes

The influence of thin 4H-SiC buffer layers grown by liquid phase epitaxy (L PE) on structural quality of 4H-SiC low-doped epitaxial layers, grown by ch emical vapor deposition (CVD) was investigated in detail. A dramatic defect density reduction in CVD epitaxial layers grown on commercial wafers with buffer LPE layer was detected. P(+)n junctions were formed on these CVD lay ers by high dose Al ion implantation followed by rapid thermal anneal. It w as shown that both the increase of diffusion lengths of minority carriers ( Lp) in CVD lavers and the forming of p(+)-layers after Al ion implantation and high temperature anneal lead to superior device characteristics. (C) 20 01 Elsevier Science B.V. All rights reserved.