Homoepitaxial SiC Growth by Molecular Beam Epitaxy

The homoepitaxial growth of SiC thin films by solid- and gas-source molecular beam epitaxy is reviewed and discussed. Our recent results regarding the homoepitaxial growth of single crystal 3C-SiC(111) and 6H-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 temperatures between 1000 and 1500 °C using SiH₄ and C₂H₄. They contained double positioning boundaries and stacking faults and the surface morphology and growth rate depended strongly on temperature. Films of 6H-SiC(0001) with low defect densities were deposited at high growth rates on vicinal 6H-SiC(0001) substrates by adding H₂ to the reactant mixture at temperatures between 1350 and 1500 °C. At temperatures below 1350 °C, only the cubic phase was formed. A kinetic analysis of the SiC deposition process is also presented. The SiC films were 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 mobility of 434 cm² V^—1 s^—1, the highest room temperature value ever reported for this polytype. Both the 6H-SiC(0001) and the 3C-SiC(111) epilayers were controllably doped using a NH₃/H₂ mixture (for lighly n-doped films), pure N₂ (for heavily n-doped SiC epilayers) and Al evaporated from a standard effusion cell (for p-type doping).