Papers by Keyword: ZnO Films

Abstract: ZnO films were deposited by magnetron sputtering using RF power supply, in order to study the effect of substrates on quality of the prepared films. Then, growth of the ZnO films on thin AlN buffer layer and Si(100) substrates were characterized using different techniques. The surface morphology was investigated by means of scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The structural properties were investigated via X-ray diffraction (XRD) patterns, Rocking Curve as well as Pole figures. The ZnO films were textured and they had preferred orientation (002) and the crystallinity was better for ZnO/Si in the used growth conditions. The XRD results were confirmed by HRTEM. Optical properties were analyzed by photoluminescence (PL), as well as electrical characteristics were performed by C-V and I-V measurements. The dispersion orientation of these films, as indicated via the FWHM (rocking curves), is small for thin ZnO/Si. These results are considered as hopeful for piezoelectric applications.

Abstract: In this research, zinc oxide (ZnO) films were prepared using a wet chemical reaction via a microwave technique. X-ray diffraction techniques (XRD) and energy dispersive x-ray spectroscopy (EDS) were used to study the phases, crystalline structures, chemical compositions and optical properties of the films, respectively. Optical transmittance was also measured through UV-VIS spectroscopy. Surface film morphologies were investigated by scanning electron microscopy (SEM). As a result, a ZnO phase with a hexagonal structure was detected. The EDS spectrum shows that elements of Zn and O were present. The average optical transmittance value for all films was 75% at a wavelength of 370-375 nm, a comparison among the films obtained at different times show a transmittance value slightly higher for films obtained at higher times. A calculation of the energy band gap of ZnO films was estimated to be in the range of 3.31 to 3.35 eV. Additional, the ZnO films showed a smooth surface.

Abstract: ZnO nanostructures such as nanowires and nanorods are beneficial in solar energy harvesting because they provide a structure with a large surface area. Also, they provide a direct pathway to electron transportation, eliminating the scope for grain boundary scattering. In this investigation, thin ZnO films were prepared by thermal evaporation of the Zn metal, which was followed by oxidation. Evaporation parameters and oxidation temperatures were fixed. The oxidation duration was the variable. The effect of oxidation time, on the morphology and structural properties were studied by using scanning electron microscopy and X-ray diffractometry. The study shows that with increase in oxidation time, the morphology changed to nanorods from initial flake morphology. As a function of oxidation time, the crystallinity and texture became more dominant. By using, I-V characteristic curves, it was found that the morphology changes alter the surface electrical conductivity of the prepared ZnO films.

Abstract: The optical and electric transport properties of the Al:ZnO(AZO) and (Cu, Al):ZnO (CAZO) films deposited by pulsed laser deposition (PLD) were investigated in this paper. The experiment found the optical band gap (OBG) of AZO films at room temperature increased from 3.378eV of ZnO to 3.446eV of ZnO:Al (2min) sample, but decreased as continue add Al to ZnO:Al (4min), which were attributes to the Burstein-Moss (B-M) effect. For CAZO films, there is obvious change about hall mobility, ν, and resistivity, ρ, after doped Cu. It can be found that the ν decreased from to and the ρ increased from to for AZO and CAZO, respectively, which is due to the scattering increasing between donor carriers and grain boundary as Cu²⁺ ions increase, meanwhile, it was also found the decrease of OBG, which are very help to further understand the electric transport properties and the OBG effect of AZO-based films as well as its devices potential application.

Abstract: The possibility of functional nanostructured materials for electronic devices synthesis by sol-gel method have been discussed such as ferroelectrics (SrBi₂(Ta_xNb_1-x)₂O₉) , ferromagnetics (Fe_xCo_yO_z) and semiconductors (ZnO). The structural features of the surface (AFM), crystallization behavior (XRD) during the heating and properties of synthesized films are discussed. Achieved parameters suggest the possibility of using synthesized SBTN sol-gel films in non-volatile memory devices, semiconductors active ZnO layers in solar sells, ferromagnetics Fe_xCo_yO_z films in radioabsorbing covers.

Abstract: Since transparent conducting oxides can be as a buttom layer of complex film electrodes, electrodeposition technique may produce ZnO films depending on variety conditions and modified surface layers of substrates in electrochemical procedures. Here we invested the structure and morphologies of ZnO films by using modified surface of the substrate-ZnO/ITO/polymer-PEN and ZnO doped Ga/ ITO/polymer-PEN.

Abstract: In this work, ZnO films were fabricated by sol-gel spin coating technique. Different spinning speeds of 1000 to 6000 revolutions per minute (RPM) were used in order to study the changes on the properties of the ZnO films. The characterizations were conducted using surface profilometer for thickness measurement, atomic force microscopy (AFM) for surface scanning, X-ray diffractometer (XRD) for structural analysis, and ultraviolet-visible (UV-VIS) spectrophotometer for optical transmittance. The influence of spinning speed and the mechanisms which affect the growth of the ZnO films will be revealed.

Abstract: In the present work, we investigated the effect of sputtering power on the structural and optical properties of ZnO films by radio frequency (rf) magnetron sputtering. Atom force microscopy (AFM), X-ray diffraction (XRD) and Prism coupling method were adopted to investigate the structure and optical properties of ZnO thin films deposited by sputtering powers in the range from 100~150W. XRD and AFM results shown that ZnO films with high c-axis preferred orientation crystalline structures have been successfully deposited under higher sputtering power condition. Moreover, it was also found that the indexes refractive of the films obtained by higher sputtering power are less than that of the bulk ZnO materials, which is closer to Crystal Refractive index.

Abstract: Zinc oxide (ZnO) films are grown by two methods-pulse laser deposition (PLD) and radio-frequency magnetron sputtering at various oxygen ambiences. Based on x-ray diffraction spectra and photoluminescence (PL) spectra, effects of the oxygen ambient on the grain size and emission properties of the ZnO films are investigated. For the samples grown by PLD, the PL spectrum consists of a single ultraviolet (UV) peak except one sample deposited at a low O₂ pressure of 7 Pa. All the samples grown by sputtering have both a UV peak and a green emission. The disappearance of the green emission of the PLD samples is ascribed to deficiency of oxygen vacancies (O_v), and the green emission of the sample grown by sputtering is due to abundant O_v. The intensity change of the UV emission is due to the variation of exciton emission, which is related to grain size and stoichiometry. The position shifting of the UV peak of the PLD samples originates from the Zn interstitial-related degradation of stoichiometry.