THE MATERIAL QUALITY OF CVD-GROWN SIC USING DIFFERENT CARBON PRECURSORS

We report an investigation where nine different hydrocarbons have been used as carbon precursor in the growth of 4H and 6H silicon carbide ( SiC) epitaxial layers. For the various growths the C/Si ratio was vari ed from 2 to 6, the temperature in the range 1550-1600 degrees C, and the growth rate was about 3-4.6 mu m/h. All hydrocarbons, except metha ne, could be used for growth of high crystal qualify epitaxial layers at low C/Si ratio and low growth rate (3 mu m/h) as confirmed by the s mooth morphology, and by low-temperature photoluminescence showing str ong free exciton and narrow well-resolved nitrogen-bound exciton lines . Hydrogen-related lines could be observed in the spectra of epitaxial layers grown with C-precursors which have double and triple bonds in the molecule. The unintentional incorporation of p-type dopants, such as, aluminium and boron impurities is proposed to correlate to the sur face roughness. Propane gave the most stable growth of the hydrocarbon s as C-precursor at higher growth rate.