SiC/Si(111) film quality as a function of GeH4 flow in an MOCVD reactor

Due to large lattice and thermal expansion coefficient mismatches, SiC films grown on Si are usually low quality. To provide a more stable growth front we added Ge in the form of GeH₄ to the reactant gases in a MOCVD reactor. Several SiC films with Ge flow rates ranging from 0–50 sccm were grown on (111) Si substrates at 1000°C. TEM results show that the crystalline quality is amorphous or polycrystalline for Ge flow rates at or below 15 sccm. Samples grown at Ge flow rates at or exceeding 20 sccm have an initial layer of single crystalline 3C SiC followed by heavily twinned crystalline 3C SiC. In particular, the samples grown with 20–30 sccm Ge contain an 80 nm initial layer of reasonably high quality single crystal 3C SiC.