Showing papers by "Songyou Wang published in 2004"

Ab initio molecular dynamics simulation of liquid Al x Ge 1-x alloys

Abstract: First-principles molecular dynamics simulations are carried out to study the structural, dynamical, and electronic properties of liquid ${\mathrm{Al}}_{x}{\mathrm{Ge}}_{1\ensuremath{-}x}$ with 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 of aluminum concentration. The concentration dependence of static structure factors, pair correlation functions, diffusion constants, and electronic density-of-states at temperature of 1250 K are investigated. The structural properties obtained from the simulations are in good agreement with neutron scattering experimental results.

Structural and Optical Investigation of GaN Grown by Metal-Organic Chemical Vapor Deposition

Abstract: Structural and optical properties of GaN grown on (0001)-oriented sapphire substrates by low pressure metal-organic chemical vapor deposition were investigated by XRD, ellipsometry, PL and other optical methods. The thickness of the GaN sample was about 1.5 μm. Seen by XRD, the existence of the strong (0002) diffraction peak with a very narrow FWHM value of 0.1 and the high order GaN (0004) diffraction peak confirms a good quality of the GaN films grown on sapphire substrate by using a multi-step growth procedure. Optical transparency of the GaN samples induces strong interference oscillations below E0 (3.44eV) in the measured dielectric function spectra and reflective spectra. In low temperature PL spectra, the red shift of the peak and decreased intensity of PL are visible. The former can be attributed to the involvement of band tail states, and the latter can be accounted for by the decreasing non-radiative recombination lifetime.