Boron diffusion into 6H-SiC through graphite mask

Abstract

Experimental results are reported of selective diffusion of boron in 6H−SiC. Photoluminescence spectroscopy scanning electron microscopy cathodoluminescence imaging, secondary-ion mass spectroscopy optical microscopy, and stain-groove technique were used to characterize the selectively doped regions fabricated by diffusion from the vapor phase through a graphite mask. Local p-doped regions of dimensions down to ∼20 μm in diameter were formed on an n-type substrate using the graphite mask. Maximum concentration of boron atoms at the surface, obtained by SIMS, varied from 3×1019 cm−3 to 6×1019 cm−3, depending upon the temperature of diffusion, while the p-n junction depth measured by the stain-groove technique varied from 0.5 μm to 1.2 μm. Planar p-n junction diodes fabricated on the diffused regions exhibited good rectification characteristics with a breakdown voltage of about 1000 V.