Zhuangjian Zhang

A new transparent conductive thin film In2O3:Mo

Abstract A new high quality transparent conductive thin film In2O3:Mo (IMO) was prepared by conventional thermal reactive evaporation at the substrate temperature of approximately 350°C. From X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis of IMO films, it was confirmed that Mo6+ substituted In3+ without changing the cubic bixbyite structure of In2O3 and there were no new compounds in IMO as well. One atom of dopant contributes with more electrons to the electrical conductivity and at the same carrier concentration there is fewer dopant in IMO than in other doped oxides. So, the IMO film exhibits simultaneously higher values of Hall mobility, electric conductivity, visible light transmittance, infrared reflectance and plasma wavelength. An electrical resistivity as low as 1.7×10−4 Ω cm was obtained, while the infrared reflectance above 4 μm and the average total visible light transmittance of the IMO film plus the glass substrate were both over 80%, and the plasma wavelength was at approximately 2.2 μm. IMO is more suitable for the energy efficient windows used in cold climates or even for optoelectronic device applications.

Molybdenum-doped indium oxide transparent conductive thin films

We developed a novel transparent conductive film, molybdenum-doped indium oxide (IMO). Using normal thermal reactive evaporation without any special treatments, IMO films have been prepared on normal glass microscope slides at about 350 °C with electrical resistivity of 1.7×10−4 Ω cm, mobility over 100 cm2 V−1 s−1, and an average spectral transmittance in the visible region over 80%. From x-ray photoelectron spectroscopy and x-ray diffraction spectra of the IMO films, it is confirmed that the lattice of IMO is the same as that of In2O3 of cubic bixbyite structure, Mo6+ substitutes for In3+ in In2O3, and there are no new compounds in IMO. The valence difference of 3 between Mo6+ and In3+ is of great advantage to the IMO film with high conductivity and high transparency simultaneously.

The electrical and optical properties of molybdenum-doped indium oxide films grown at room temperature from metallic target

High performance molybdenum-doped indium oxide (IMO) films were deposited on slide glass substrates from metallic targets by using dc reactive magnetron sputtering at room temperature. The structural, electrical and optical properties have been investigated as functions of target composition and oxygen partial pressure. The deposited films were smooth and amorphous, as determined by scanning electron microscopy and x-ray diffraction, respectively. The results revealed that the as-deposited molybdenum-doped In2O3 films show good electrical property and high optical transmittance, as well as high infrared transmittance. The films prepared at oxygen partial pressure of 3.8 × 10−2 Pa and with 2 wt% Mo-doped target are characteristic of high Hall mobility of 20.2 cm2 V−1 s−1, carrier concentration of 5.2 × 1020 cm−3, and the average optical transmittance excess 90% in the visible region from 400 to 700 nm. Thus IMO films may be a potential material for novel optoelectrical devices such as an organic light-emitting diode.

Properties of transparent conductive In2O3:Mo thin films deposited by Channel Spark Ablation

Molybdenum-doped indium oxide In2O3:Mo (IMO) thin films were deposited on glass substrates by a technique called channel spark ablation. The structure, surface morphology, electrical, and optical properties of these films were investigated by x-ray diffraction, atomic force microscopy (AFM), four-point probe, ultraviolet photoelectron spectroscopy (UPS), Hall analysis, and spectrophotometry. The influence of oxygen pressure on the electrical properties of IMO thin films prepared at Ts=350°C was studied, showing that increasing oxygen pressure changes the resistivity concavely and the carrier concentration convexly. The IMO films as deposited are well crystallized with a preferred orientation of (222) and the surface roughness evaluated in terms of Rrms, Ra, and Rp-v measured by AFM is 0.72, 0.44, and 15.4 nm, respectively. The lowest resistivity and corresponding carrier concentration are 4.8×10−4Ωcm and 7.1×1020cm−3. The typical work function of IMO is 4.6 eV measured by UPS. For all the samples, the ave...

Preparation of Molybdenum-doped Indium Oxide Thin Films Using Reactive Direct-current Magnetron Sputtering

High-mobility molybdenum-doped In 2 O 3 films (IMO) were prepared on the normal glass substrate by reactive direct current magnetron sputtering from the molybdenum-embedded indium metal target. The effects of oxygen partial pressure, substrate temperature, and sputtering current on the optoelectrical properties of IMO films were investigated. The films with the highest carrier mobility of 50 cm 2 V −1 s −1 , as well as the average visible transmission greater than 80% including the 1.2-mm-thick glass substrate, were obtained. The minimum resistivity of the films is 3.7 × 10 −4 ohm cm. The properties of the IMO films are sensitive to the oxygen partial pressure in the sputtering environment. X-ray diffraction measurements indicate that the films show In 2 O 3 crystal structure.

Electrical and optical properties of molybdenum-doped ZnO transparent conductive thin films prepared by dc reactive magnetron sputtering

Molybdenum-doped ZnO (ZMO) transparent conductive thin films were prepared by dc reactive magnetron sputtering on glass substrates from metallic targets. The structure, surface morphology, chemical state, optical and electrical properties of ZMO films were studied. The XRD pattern confirmed that ZMO thin films were polycrystalline with the hexagonal crystal structure, and the surface morphology measured by AFM demonstrated that the surface was smooth and compact. Chemical state analysis revealed that molybdenum atoms existed mainly in Mo6+ and Mo5+ ions but not in only single oxidation states. The minimum resistivity of 7.9 × 10−4 Ω cm is obtained with a carrier mobility of 27.3 cm2 V−1 s−1 and a carrier concentration of 3.1 × 1020 cm−3, and the average transmittance is more than 85% in the visible light region. The refractive index and extinction coefficient at the wavelength of 550 nm are 1.853 and 7.0 × 10−3, respectively. The energy bands increase from 3.37 eV to 3.8 eV with the increase in carrier concentrations and the carrier effective mass m* is 0.33 times the electron mass.

Defect-mode dependence of two-photon-absorption enhancement in a one-dimensional photonic bandgap structure

A one-dimensional photonic crystal containing a single CdS defect layer of various thicknesses was fabricated. The dependence of the two-photon-absorption (TPA) coefficient on the defect mode was investigated by use of a femtosecond pump-probe method. Experimental results show that the TPA coefficient of the CdS defect layer depends strongly on the defect mode in the photonic bandgap. This is consistent with the predicted dependence of light intensity within the defect layer.

Development of novel tungsten-doped high mobility transparent conductive In2O3 thin films

A novel high mobility transparent conductive oxide thin film, tungsten-doped indium oxide (IWO), has been successfully grown on conventional glass substrates by reactive direct current magnetron sputtering technique from a metallic target. Analyses of x-ray photoelectron spectroscopy and x-ray diffraction reveal that tetravalent and hexavalent tungsten ions substitute for trivalent host indium ions without changing the crystalline structure of In2O3. IWO thin films were grown with resistivity of 4.4×10−4Ωcm, carrier mobility of 52.8cm2V−1S−1; transmittance exceeding 80% at wavelengths between 380 and 900nm, and average roughness of 7.5nm.

Visible Light Photoelectrochemical Response of Carbon- Doped TiO2 Thin Films Prepared by DC Reactive Magnetron Sputtering

Carbon-doped TiO2 thin films were prepared by direct current (DC) reactive magnetron sputtering at room temperature in Ar/O2 ambience, using a titanium target incrusted with graphite pieces. The films as prepared were characterized by X-ray diffraction (XRD), UV-Vis transmission spectra, and photoelectrochemistry methods. The XRD patterns of the films showed that the doping of carbon was beneficial to the crystallization of the films. When the ratio of area of C/Ti was less than 0.10, the crystallization of the films increased with the increase in graphite area in the target. The band gap of the films decreased from 3.4 eV (pure TiO2 films) to 3.1 eV when the ratio of area of C/Ti in the target was 0.05. The photoelectrochemical property of the films improved when the ratio of area of C/Ti in the target was less than 0.10. When this ratio was 0.10, the photocurrent density of the films was 0.069 μA·cm−2 at 0 V under visible light illumination. However, an abnormal photoelectrochemical response was observed when the ratio of area of C/Ti in the target was 0.16.

Molecular beam study of laser-induced chemical etching of Si(111) by chlorine molecules

Chemical etching of Si(111) surface by chlorine molecules under 355 and 560 nm irradiation has been studied using a continuous wave supersonic molecular beam. Only two products, SiCl and SiCl2, were observed. The translational energy distributions of the gaseous products have been measured as a function of laser fluence, and can be fitted with Maxwell–Boltzmann distributions. Study on the effect of translational energy of incident chlorine molecules on the reaction rate is also presented for the first time.