HOMOEPITAXIAL SIC GROWTH BY MOLECULAR-BEAM EPITAXY

The homoepitaxial growth of SiC thin films by solid- and gas-source mo lecular beam epitaxy is reviewed and discussed. Our recent results reg arding the homoepitaxial growth th of single crystal 3C-SiC(111) and 6 H-SiC(0001) thin films are also presented. The 3C-SiC(111) films were grown on both vicinal and on-axis 6H-SiC(0001) substrates at temperatu res between 1000 and 1500 degrees C using SiH4 and C2H4. They containe d double positioning boundaries and stacking faults and the surface mo rphology and growth rate depended strongly on temperature. Films of 6H -SiC(0001) with low defect densities were deposited at high growth rat es on vicinal 6H-Sic(0001) substrates by adding H-2 to the reactant mi xture at temperatures between 1350 and 1500 degrees C. At temperatures below 1350 degrees C, only the cubic phase was formed. A kinetic anal ysis of the SiC deposition process is also presented. The SiC films we re resistive with an n-type character and a lower N concentration than the p-type CVD-grown epilayers of the substrate. Undoped 6H-SiC films with the lowest atomic nitrogen and electron concentration had a mobi lity of 434 cm(2) V-1 s(-1): the highest room temperature value ever r eported for this polytype. Both the 6H-SiC(0001) and the 3C-SiC(111) e pilayers were controllably doped using a NH3/H-2 mixture (for lighly n -doped films), pure Nz (for heavily n-doped SiC epilayers) and Al evap orated from a standard effusion cell (for p-type doping).