Formation of SiC Delta-Doped-Layer Structures by CVD

Ultranarrow n-type delta-doped-layers of 4H-SiC are grown utilizing the vertical hot-wall-type CVD system. A single N2 gas pulse is injected within the ON period of the pulse valve during the epitaxial growth. The peak carrier concentration and full-width at half-maximum (FWHM) of the doped layer grown with the ON period of 700ms are 9 x 1018cm-3 and less than 2 nm, respectively. The peak concentration increases as the ON period increased from 0 to 700ms, while the FWHM decreases with increased ON period. The uniformities of the peak position and the peak concentration of n-type delta-doped-layer are evaluated to be around 8% and 12%, respectively, excluding 5mm at 2-inch wafer edge. Furthermore, formations of p-type delta-doped-layers with growth rate of 5 *mm/hr are investigated by utilizing single pulse-doping procedure. Secondary ion mass spectroscopy profile indicates that very narrow p-type delta-doped-layers are also successfully grown. The well-defined delta-doped-layer structure is confirmed by using cross-sectional transmission electron microscopy.