Material quality improvements for high voltage 4H-SiC diodes

The influence of thin 4H-SiC buffer layers grown by liquid phase epitaxy (LPE) on structural quality of 4H-SiC low-doped epitaxial layers, grown by chemical 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 layers by high dose Al ion implantation followed by rapid thermal anneal. It was shown that both the increase of diffusion lengths of minority carriers (Lp) in CVD layers and the forming of p+-layers after Al ion implantation and high temperature anneal lead to superior device characteristics.