Li-Jian Meng

Investigations of titanium oxide films deposited by d.c. reactive magnetron sputtering in different sputtering pressures

Titanium oxide thin films were deposited on glass substrates by the d.c. reactive magnetron sputtering method. The dependence of structural and optical properties of films, and film composition, on the sputtering pressure was studied. The results of the X-ray diffraction show that all films only have the anatase TiO2 phase. At lower sputtering pressure, the film has a preferred orientation along (101) direction. As the sputtering pressure increases, the intensity of the (101) diffraction line decreases gradually. When the sputtering pressure is higher than 2 × 10−2 mbar, the film exhibits an almost amorphous structure. The results of scanning electron microscopy show that the film structure changes from more dense to more porous as the sputtering pressure increases from 2 × 10−3 mbar to 2 × 10−2 mbar. These structure variations in result in the variations in the optical properties. As the sputtering pressure increases from 2 × 10−3 mbar to 2 × 10−2 mbar, the refractive index n and extinction coefficient k (at 500 nm) vary from 2.48 to 2.14 and from 4.06 × 10−3 to 0.59 × 10−3 respectively.

Properties of indium tin oxide films prepared by rf reactive magnetron sputtering at different substrate temperature

Abstract Indium tin oxide (ITO) films were deposited onto the glass substrates at different substrate temperatures (RT-500°C) by rf reactive magnetron sputtering method. The structural, optical and electrical properties of ITO films have been characterized by X-ray diffraction, scanning electron microscopy, optical transmittance and reflectance, sheet resistance and electrical resistivity measurements. The films deposited at low substrate temperature have a very strong (222) diffraction peak which means a preferred orientation along the [111] direction. As the temperature is increased, the (400) diffraction peak intensity increases and results in a preferred orientation along [100] direction for the films prepared at 500°C substrate temperature. The film prepared at 400°C substrate temperature has the lowest electrical resistivity (about 3.7×10 −4 Ω cm).

Amorphous ITO thin films prepared by DC sputtering for electrochromic applications

Indium-Tin-Oxide (ITO) thin films were deposited on glass substrates using DC magnetron reactive sputtering at different bias voltages and substrate temperatures. Some improvements were obtained on film properties, microstructure and other physical characteristics for different conditions. Amorphous and polycrystalline films can be obtained for various deposition conditions. The transmission, absorption, spectral and diffuse reflection of ITO films were measured in some ranges of UV-Vis–NIR. The refractive index (n), Energy band gap Eg and the surface roughness of the film were derived from the measured spectra data. The carrier density (nc) and the carrier mobility (μ) of the film micro conductive properties were discussed. The films exhibited suitable optical transmittance and conductivity for electrochromic applications.

Study of Annealed Indium Tin Oxide-Films prepared by RF Reactive Magnetron Sputtering

Abstract Tin doped indium oxide (ITO) films were deposited on glass substrates by rf reactive magnetron sputtering using a metallic alloy target (In-Sn, 90-10). The post-deposition annealing has been done for ITO films in air and the effect of annealing temperature on the electrical, optical and structural properties of ITO films was studied. It has been found that the increase of the annealing temperature will improve the film electrical properties. The resistivity of as deposited film is about 1.3 × 10 −1 gW ∗ cm and decreases down to 6.9 × 10 −3 Ω ∗ cm as the annealing temperature is increased up to 500 °C. In addition, the annealing will also increase the film surface roughness which can improve the efficiency of amorphous silicon solar cells by increasing the amount of light trapping.

Study of the structural properties of ZnO thin films by x-ray photoelectron spectroscopy

Abstract X-ray photoelectron spectroscopy (XPS) analysis was performed on ZnO films prepared on glass substrates by DC reactive magnetron sputtering at different substrate temperatures (room temperature to 450°C). In the O 1s spectra two resolved peaks were observed. The lower energy peak, located at 530 eV, corresponds to O-Zn bonding, while the higher energy peak, located at 532 eV, could be assigned to OH(531.5 eV) and/or H 2 O(533 eV) species. As the substrate temperature is increased, the oxygen component located at higher energy decreases. This variation was correlated with the structural properties of the films. The films prepared by DC reactive magnetron sputtering generally have a columnar structure with many pores. In air some of these pores are filled with water and result in the appearance of a higher energy peak in the O 1s spectra. The decrease of the oxygen component located at higher energy indicates the decrease of the porosity of the films. The results obtained by scanning electron microscopy measurements were in agreement with this conclusion.

Direct current reactive magnetron sputtered zinc oxide thin films —the effect of the sputtering pressure

Abstract ZnO thin films were deposited onto glass substrates by d.c. reactive magnetron sputtering from a metallic zinc target. A systematic study has been made on the influence of sputtering pressure in the range from 0.2 Pa to 3 Pa on the film structural and optical properties. At low sputtering pressure (0.2–0.4 Pa), the film was inhomogeneous, non-stoichiometric and had low refractive index and an almost amorphous structure. At high sputtering pressure (0.6–0.8 Pa), the film was homogeneous, stoichiometric and had high refractive index and the crystallinity was improved. As the sputtering pressure was further increased (1–3 Pa), the homogeneity and the refractive index of the film had no clear variation, but the crystallinity of the film went down. As the sputtering pressure was increased from 0.2 Pa to 3 Pa, the transmittance of the film increased and the deposition rate of the film decreased.

Characterisation of ZrO2 films prepared by rf reactive sputtering at different O2 concentrations in the sputtering gases

Abstract Zirconium oxide (ZrO 2 ) films have been prepared by rf reactive magnetron sputtering at different O 2 concentrations in the mixture sputtering gases. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and optical spectroscopies. The influence of O 2 concentration in the sputtering gases on the microstructure, residual stress and optical properties of the films has been studied. Also, the effect of loose packing structure caused by the high O 2 gas concentration on the deposition rate has been discussed.

Properties of indium tin oxide (ITO) films prepared by r.f. reactive magnetron sputtering at different pressures

Abstract A set of indium tin oxide (ITO) films has been prepared by r.f. reactive magnetron sputtering at different total sputtering pressures using an indium tin alloy target. The effect of the pressure on ITO films properties have been studied. The pressure is varied from 0.08 to 0.76 Pa. The deposition rate does not show a significant variation with the pressure. The preferred orientation of ITO films change from the [222] to the [440] direction as the pressure is increased from 0.08 to 0.76 Pa. All the films are subject to a compressive stress. The film that prepared at high pressure show a very rough surface. All the films show a high optical transmittance. The film that prepared at low pressure give a low electrical resistivity. The lowest electrical resistivity which we have obtained in this work is about 2 × 10 −3 Ω cm.

Annealing effect on ITO thin films prepared by microwave-enhanced dc reactive magnetron sputtering for telecommunication applications

Abstract Indium-tin oxide (ITO) thin films were deposited on glass substrates at two different oxygen partial pressures (3.8×10 −4 and 1.2×10 −3 mbar). After the deposition, these films were annealed for 30 min in air at 200 °C and 400 °C, respectively. The effect of these post-deposition treatments on the structural, electrical and optical properties of ITO thin films has been studied. It has been found that annealing at 200 °C is suitable for improving the properties of these ITO films.

Zinc oxide films prepared by dc reactive magnetron sputtering at different substrate temperatures

Abstract The properties of zinc oxide films prepared by dc reactive magnetron sputtering were studied over a range of the substrate temperatures (room temperature to 450°C). The dependence of the structure of the films on the substrate temperature was studied using scanning electron microscopy and X-ray diffraction. The films had a preffered orientation along the (002) crystal plane at room temperature (50°C), a random orientation at 200–300°C and again a preferred orientation along the (002) crystal plane at 350–450°C. The grain size increased as the substrate temperature was raised. In addition, the optical and electrical properties have also been investigated.