Surface Debye temperature determination from LEED: correlation to defects in epitaxial films

摘要

Low energy electron diffraction (LEED) peak intensities were measured to estimate surface Debye temperature for epitaxially-grown silicon thin films and for bulk Si (001). Rutherford backscattering spectroscopy (RBS, random and channeling modes) and positron annihilation spectroscopy (PAS) were used to quantify defect density and distribution in the near-surface layers. The surface Debye temperature of bulk Si (001), and 1.0 mu m, and 0.6 mu m Si on sapphire were measured to be 333 K, 299 K, and 260 K, respectively. RBS and PAS showed that the defect concentration was highest near the film/substrate interface, presumably due to the lattice mismatch, and decreased toward the top surface. The thicker film presented fewer defects in the surface and near-surface layers. We showed that a larger concentration of defects Nd in Si epitaxial films correlates with a lower surface Debye temperature following the empirical relation theta D = (365 +/- 14) - (8.1 +/- 1.5) x 10-13 Nd for our set of samples. Our study suggests the further development of LEED to estimate near-surface defect concentrations.