a b s t r a c tThe strain analysis of GaN film on nitridated Si(111) substrate with different growth times between 0 and 660 s via metal organic chemical vapor deposition (MOCVD) was conducted based on the precise measurement of the lattice parameters by using highresolution X-ray diffraction (HR-XRD). The nitridation time (NT) was changed at a fixed growth condition. The a-and c-lattice parameters were measured, followed by the in-plane and out-of-plane strains. Then, the biaxial and hydrostatic components were extracted from the total strain values obtained, and were then discussed in the present study as functions of the NT. The biaxial strain and stress are also strongly affected by the non-uniformity of the SiN x buffer layer thickness.Published by Elsevier Ltd.

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The GaAs 1−x P x /GaAs ternary alloys were grown on n-GaAs (100) substrate with different P/As flux ratio by solid source molecular beam epitaxy (MBE) system using GaP decomposition source. In order to obtain smooth interface and lattice mismatch structures we have used both continuous growth (CG) and graded growth (GG) methods. The range of lattice parameters in the graded epilayer and phosphorous composition in the samples were determined by the high-resolution X-ray diffraction (HRXRD) rocking curve simulation. The critical energy points of the interband transition edges of the structures were determined by line-shape analyses on their dielectric functions (DF) using spectroscopic ellipsometry (SE) measurements at a room temperature in the 0.5-5 eV photon energy region. Also, surface and interface phenomenon of the structures were discussed by using ellipsometric data. Phosphorous compositions of the ternary alloys were also calculated by photoluminescence (PL) emission peak positions at room temperature and using the bowing parameter obtained by fitting to critical points.

Titanium dioxide (TiO 2 ) thin films were deposited on glass substrate by d.c. magnetron sputtering at 200• C substrate temperature. The thicknesses of the films were measured using stylus type profilometer. The deposited films were annealed using rapid thermal annealing (RTA) system in the O 2 ambient for 20 min at 400 and 500• C. Influence of Ar/O 2 flux ratio and annealing temperature on structural and optical properties of the samples was analyzed using X-ray diffraction (XRD) and UV-vis spectrometer in the range of 200-1100 nm. The films annealed above 400• C were crystalline with anatase phase, whereas at the as-deposited states, the films were amorphous. Optical properties such as band gap, refractive index and absorption coefficient were calculated using transmittance spectra of the samples. The influence of thermal annealing on structure and optical properties is discussed. Band gap energies of the TiO 2 films were also determined using photoluminescence(PL) measurements.