Lin Jun Wang

Characterization of Ag doped P-type ZnO thin films prepared by electrostatic-enhanced ultrasonic spray pyrolysis

In this paper, the structure, electrical and optical properties and stabilities of Ag doped p-type ZnO thin films, prepared by electrostatic-enhanced ultrasonic spray pyrolysis were investigated. XRD and Hall data analyses indicated that the resistivity of 4at. % Ag doped p-type ZnO was low, without Ag2O phase separation. The optical transmission spectra illustrated that optical band gaps decreases with the gradual increase of Ag dopant. Moreover, ZnO: Ag films placed for 10 days still showed p-type, but the optical transmittance decreased, suggesting that AgZn in the ZnO: Ag thin films captured electrons to generate Agi, which reunited to be Ag nano-particles and decreased the optical transmittance of ZnO: Ag.

Preparation and Characterization of ZnO Nanowire Arrays Grown on Different ZnO Seed Layers by Hydrothermal Method

Due to its suitable band gap, low cost, environmental friendliness, and high electron mobility, ZnO, naturally n-type semiconductor with a wide bandgap (Eg = 3.37 eV), is widely studied, as a window layer of heterojunction solar cells. In this study, the ZnO nanowire arrays were grown on the different ZnO seed layers by hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-Vis spectra were used to characterize the ZnO nanowire arrays. The results indicate the seed layer can effect the size distribution, density, crystal structure and optical properties of the nanowire arrays.

Effect of Ar Pressure on Properties of Polycrystalline CdZnTe Films

Polycrystalline CdZnTe (CZT) films were grown by close-spaced sublimation method. The CdZnTe films were prepared on fluorine doped tin oxide (FTO) glass substrates at various argon (Ar) pressures from 200 Pa to 700 Pa. A comparative study of the films at different pressures was obtained by X-ray diffraction (XRD), scanning electron microscope (SEM) and Energy dispersive spectrometer (EDS) respectively. The XRD studies revealed that CdZnTe films had a preferential orientation along the (111) phase except the one at 500 pa. EDS analysis indicated that the increasing of Ar pressure decreased Zn content.

Ni-Induced Lateral Fast Crystallization of Amorphous Silicon Film by Microwave Annealing

Polycrystalline Si (poly-Si) thin films for application to display devices and solar cell are generally fabricated by crystallizing amorphous Si (a-Si) thin film precursors. In this paper, studies on Ni-induced lateral crystallization of a-Si thin films by microwave annealing at low temperature were reported. The crystallization of a-Si thin films was enhanced by applying microwaves to the films. The poly-Si films were invested by Optical Microscopy, X-ray Diffraction (XRD) , Raman Spectroscopy and Scanning Electron Microscope(SEM). After processing of Ni-induced lateral crystallization by microwave annealing above 500°C, the a-Si has begun to be crystallized with large grains having the main (111) orientation. The rate of crystallization at 550°C is about 0.033μm/min. Compared to Ni-induced lateral crystallization by conventional furnace annealing, Ni-induced lateral crystallization by microwave annealing both lowers the crystallization temperature and reduces the time of crystallization. The crystallization mechanism during microwave annealing was also studied. The technique that combines Ni-induced lateral crystallization with microwave annealing has potential applications in thin-film transistors (TFT’s) and solar cell.

Tourmaline@ZnO Core–Shell Structural Composites: Fabrication, Characterization, and Optical Properties

Based on natural tourmaline particles as the inner core and zinc acetate solution as the Zn source, ZnO shell layers have been fabricated by the facile synthesis routine of chemical bathing deposition under different reaction temperatures. The structural and crystalline characterization of the core–shell composites are determined experimentally by Raman spectra and x-ray diffraction. The morphological and componential investigations are achieved by scanning electron microscopy, high-resolution transmission electron microscopy and energy dispersive spectrometer. The absorptive and luminescent properties are explored by ultraviolet–visible absorption spectroscopy and photoluminescence spectroscopic measurements. The photocatalytic performances are evidenced under Xenon lamp irradiation utilizing methyl orange dye as the model compound. The results indicate that the catalysis efficiencies of the hybrid tourmaline@ZnO products are relatively superior in lower temperature cases, while the contributions originating from the tourmaline core to the crystal growth and catalytic activity of ZnO are further elucidated.

Effects of the Substrate Temperature on the Structure and Properties of Cd1-xMnxTe Films

Cd1-xMnxTe (CdMnTe) can be a good candidate for gamma and X-ray detection because of its wide band-gap, high resistivity, and good electro-transport properties. Polycrystalline CdMnTe films were grown by closed-space sublimation method on glasses at different substrate temperatures. In this paper, substrate temperature dependent surface morphology, chemical composition, structural and electrical properties of CdMnTe films are investigated systematically.

Influences of Working Power on Properties for Boron Films Deposited by R. F. Magnetron Sputtering

Boron and boron-rich boride has attracted considerable attention in the past few years for their wide varieties of structures and property associated with their unusual three-center electron-deficient bonds. Boron film also exhibits many unique and fascinating properties, such as high melting point (~ 2500K) with low density, high harness close to diamond, and excellent thermoelectric property. In this paper, boron (10B) films were prepared on (100) silicon substrate by radio frequency (r. f.) magnetron sputtering method under the different working pressure and power with a target of boron and boron oxide (B:B2O3 40wt%). After 3 hours sputtering deposition, the substrate was covered with boron films tightly. The morphology of deposited films under different temperature was characterized by high resolution scanning electron microscopy (HRSEM), FTIR spectrum (FTIR), Raman spectrum (Raman). The results show that the film contains boron and little oxygen. At last, the growth mechanism of B film was analyzed.

Preparation of Graphene Films and their Applications in Dye-Sensitized Solar Cells

A facile and rapid deposition process is developed for the fabrication of large-area graphene films by scalpel technology using graphene nanopartical as material. Graphite oxide (GO) was synthesized using modified Hummers method. Graphene nanopartical was fabricated by a reducing process in which GO was well reduced by hydrazine hydrate. The crystal structure and photoelectric properties of graphene and graphene films were investigated by X-ray diffraction. The composition of production (GO and graphene) is investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy technology. Surface morphology of graphene layers were observed by SEM. Then, the semitransparent conductive films were applied to backside illumination DSSC. As a result, the maximum power conversion efficiency (PCE) is as high as 0.2558% and the fill factor is 30.97%.

Growth of ZnS Films and Application in Heterojunction

ZnS films were prepared by radio-frequency (RF) magnetron sputtering method. The effects of substrate temperature and annealing treatment on the properties of ZnS films were studied. The ZnS films were characterized by X-ray diffraction (XRD), UV-visible spectrophotometer, and electrical measurements. The results showed that the higher substrate temperature and post-deposition annealing treatment was helpful in improving the crystalline quality of the films, and the film had an n-type conductivity. N-type ZnS films were also deposited on p-type single-crystalline silicon (Si) substrates to fabricate ZnS/ Si heterojunction. The current-voltage (I-V) characteristic of the heterojunction was examined, which showed a rectifying behavior with turn-on voltage of about 2V.

Low-Temperature Ni Acetate Induced Crystallization of a-Si Thin Film by Microwave Annealing

This paper investigates a combination of Ni acetate solution induced crystallization and microwave induced crystallization of a-Si thin film. Ni acetate solution was coated over amorphous Si thin film for evenly spread of Ni metal source. The Ni inducing source was formed from Ni acetate powder dissolved in de-ionized water or ethanol. The crystallization using Ni acetate solution was a Ni-silicide mediated process, the same process used with Ni metal layer. Compared to Ni metal layer induced crystallization by conventional furnace annealing, it finds that the crystallization temperature was lowered to 450 °C and the time of crystallization was reduced. Using Ni acetate solution induced crystallization is propitious to big area crystallization. After the processing, the poly-Si grain size was found about 0.1-0.5μm. The crystallization of a-Si thin films was enhanced by applying microwaves and Ni acetate solution to the thin films. The technique that combines Ni solution induced crystallization with microwave annealing has potential applications in thin-film transistors (TFT’s) and solar cell.