The effect of Ge on the structure & morphology of SiC films grown on (111) Si substrates

Due to the lack of isomorphism and the large lattice and thermal expansion coefficient mismatch, SiC films grown on Si are usually low quality and grow three dimensionally. To stabilize the growth front we grew several SiC films on Si (111) substrates with GeH4 flow rates ranging from 0 - 50 sccm in a MOCVD reactor at 1000 degreesC. SiC films grown with GeH4 flow rates at or below 15 sccm consist of amorphous and/or small polycrystalline grains. Samples grown with GeH4 flow rates at or exceeding 20 sccm consist of crystalline 3C grains, and have a single crystalline initial layer followed by a heavily twinned crystalline layer. The initial layer consists of up to 80 nm of high quality single crystal 3C SiC, which could possibly be used as a buffer layer for either cubic nitride growth or for further SiC growth without Ge.