Structure of SiC-Quantum Wells Studied by TEM and CBED

Abstract

Summary and Conclusion SiC hetero-polytypic structures have been investigated by conventional and high resolution TEM and the lattice parameters of a thin cubic stripe have been determined by CBED. For the case of the stepped substrate, nearly free of defects, about 2nm thick cubic stripes are formed within the hexagonal layer. For the case of the growth on on-axis substrates, it was demonstrated that 6H/3C as well as 4H/3C stacks are formed on 6H and 4H-SiC substrates, respectively, By CBED the lattice parameters of the cubic stripe were determined to a rhom =0.4360nm a rhom = (89.78±0.02)° demonstrating the rhombohedral distortion of the 3C stripes. It might be suggested that the result is valid also for the 2nm thick cubic stripes in the multi-quantum well structures grown on the stepped SiC substrate, although such layers are generally to thin for the lattice parameter determination by CBED. Acknowledgements The authors are indebted to Dr. A. Chuvilin for the generous scientific support during his stay as guest scientist at Jena University, thank Ch. Zaubitzer for sample preparation and acknowledge the financial support of the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 196.