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Polycrystalline Pb(Zr0.35Ti0.65)O3 thin films prepared on Pt/Ti/SiO2/Si substrate by using solgel technique were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM). The optical properties of the films were investigated by using spectroscopic ellipsometry (SE) with a four-phase optical model, air/roughness layer/PZT layer/Pt layer in the spectral range of 300–800 nm. The optical band gap of the films calculated following the Tauc’s Law was smaller than that of an amorphous PZT thin film with some microcrystals existing on the surface. The result indicates that the quantum-size effect leads to an increase in band gap when the crystalline dimensions become very small.

Based on density functional theory (DFT) within the generalized gradient approximation (GGA) using the CASTEP code, we calculated the formation energy of a Cu vacancy, as well as the band structure and the optical properties of β-CuSCN with Cu vacancies. Removal a Cu atom from the 32-site and the 72-site supercell results in an enlargement of the band-gap and a slight relaxation in the lattice parameter. An accepter level above the valence band maximum is observed in the 32-site supercell with a Cu vacancy, which results in the onset of a small absorption pre-peak at 0.65 eV.

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.