X-ray Structure Analysis of Semiconductor Insulator Film Systems

Reaching the nanometerscale, new approaches for the fabrication of thin and smooth heteroepitaxial films have to be found. Here, the material system CaF2/Si is a promising candidate due to small lattice mismatch (0.6%) and similar lattice structure. In this work the growth of CaF2 on Si(111) and the following deposition of Si and Ge on the CaF2 films was investigated by means of surface x-ray diffraction (SXRD), x-ray reflectivity (XRR) and atomic force microscopy (AFM). Films were grown at temperatures of 500 degrees C and 600 degrees C with thicknesses of 1-10nm. With decreasing thickness and temperature the adlayer partially relaxes as can clearly be seen in the lateral seperation of the CaF2 reflexes. However, the intensity distribution of the crystal truncation rods (CTR) leads to a model of a very smooth and crystalline film. The following deposition of semiconductors in a two step method (RT deposition and annealing under surfactant flux) results in crystalline layers with small roughness