Diffraction gratings are becoming increasingly widespread in optical applications, notably in lasers. This study presents the work on the characterization and evaluation of Multilayer Dielectric Diffraction Gratings (MDG) based on the finite element method using Comsol MultiPhysics software. The optimal multilayer dielectric diffraction grating structure using a rectangular three-layer structure consisting of an aluminum oxide Al2O3 layer sandwiched between two silicon dioxide SiO2 layers on a multilayer dielectric mirror is simulated. Results show that this MDG for non-polarized lasers at 1064 nm with a significantly enhanced −1st diffraction efficiency of 97.4%, reaching 98.3% for transverse-electric (TE) polarization and 96.3% for transverse-magnetic (TM) polarization. This design is also preferable in terms of the laser damage threshold (LDT) because most of the maximum electric field is spread across the high LDT material SiO2 for TE polarization and scattered outside the grating for TM polarization. This function allows the system to perform better and be more stable than normal diffraction grating under a high-intensity laser.

In this paper, ZnO nanorods were grown by wet chemical method on p-Si (100) substrate to form n-ZnO nanorods/p-Si (100) heterojunction. The optical, electrical, structural properties of n-ZnO nanorods/p-Si(100) heterojunction were analyzed by the photoluminescence (PL) spectroscopy, [Formula: see text]–[Formula: see text] measurement, X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The room temperature PL spectra reveal the good optical property of the heterojunction with strong UV peak at 385[Formula: see text]nm. The ZnO nanorods were vertically well-aligned on p-Si (100) and had an average height of about 1.6[Formula: see text][Formula: see text]m. The n-ZnO nanorods/p-Si (100) heterojunction also exhibits diode-like-rectifying-behavior.

Vanadium and nitrogen co-doped TiO2(TiO2:(V, N)) thin films were fabricated by sol–gel method. Crystal structure, surface morphology, chemical composition and absorption edge of the thin films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and UV-Vis spectroscopy techniques, respectively. Photocatalytic activity of all thin films were evaluated by measuring decomposition rate of methylene blue solution under visible light irradiation. The water contact angle analyzer was used to measure water contact angle on the film. The results indicate that absorption edge of TiO2:(V, N) thin films shifts to visible region. All co-doped TiO2 samples show higher visible light photocatalytic activity than undoped TiO2 and single-element-doped TiO2 counterparts. The best TiO2:(V, N) thin film can decompose about 90% MB solution and gets super wet state after 150[Formula: see text]min under compact light irradiation.

In this paper we focus on silicon nanowires (Si-NWs) which were fabricated on transparent conductive substrates by plasma-enhanced chemical vapor deposition (PECVD) method using Sn as stimulated catalyst metal. Transparent conductive substrates which we used are ZnO fabricated by direct current (dc) sputtering. Property of ZnO thin film was investigated by x-ray diffraction (XRD), volt-ohm-miliampere (VOM) meter, and Stylus method. In order to grow Si-NWs using PECVD we need to use metal as catalyst. We used Sn as catalyst to synthesize Si-NWs. Sn catalyst nanoparticles were fabricated by high vacuum evaporation system (SenVact). Size and density of Sn catalyst nanoparticles were investigated by scanning electron microscope (SEM). The influence of the thickness of metal layers on forming Sn catalyst nanoparticles was studied. In particular, the factors affecting the formation of Si-NWs such as temperature and rate of gas were examined. Si-NWs’ properties were investigated by SEM, Raman spectroscopy and energy dispersive x-ray (EDX) spectrocopy.