Large area silicon carbide devices fabricated on SiC wafers with reduced micropipe density

Silicon carbide devices are being developed for high-power applications. High current operation of these devices is limited by substrate quality. In SiC substrates, micropipes (sometime referred to as micro pores) are a common defect. The presence of even a single micropipe defect intersecting the active region of the device has been shown to produce pre-mature electric breakdown. As a result, the active area of SiC devices usually does not exceed 1 mm2. In order to fabricate high-power SiC devices, operating at currents of 100 A and higher, the device area must exceed 10 mm2 (using reasonable values of current density possible in SiC). Recently, we reported on the fabrication of silicon carbide epitaxial wafers with reduced micropipe density (Rendakova et al., J. Electron Mater. 27 (1998) 292). The best R&D wafers 35 mm and 41 mm in diameter, both 6H and 4H polytypes, have no micropipes. We proposed these wafers as substrates for SiC high-power devices (Chelnokov et al., Diamond and Related Mater. 6 (1997) 1480–1484). In this paper, we report on the fabrication of large area Schottky barriers (up to 8 mm2) based on 4H-SiC layers grown on SiC wafers with reduced micropipe density. Schottky barriers produced on this material demonstrate that large devices can be fabricated without the usual degradation associated with the presence of micropipes.