Micropipe dissociation has been investigated in homoepitaxial growth of 4H-SiC(03 (3) over bar8) by chemical vapor deposition. Almost complete (similar to100%) closing of micropipes was realized, although some of very large (> 3 mum) micropipes were threading into epilayers. Based on KOH etching experiments on various epilayers, the authors propose a model of micropipe dissociation in 4H-SiC(03 (3) over bar8) epitaxial growth. The reverse characteristics of Ni/4H-SiC(03 (3) over bar8) Schottky barrier diodes were significantly improved by micropipe closing.