Guangpu Wei

Investigations on Sb2O3 doped-SnS thin films Prepared by vacuum evaporation

Tin sulfide (SnS) is one of promising candidate materials for low-cost thin film solar cells because of its high absorption coefficient and suitable band-gap. The aim of this paper is to study the properties of doped-SnS thin films prepared by vacuum evaporation. Sb2O3 was used as the doping source (the weight ratio of Sb2O3 to SnS in the range from 0.1% to 0.8%). And then the Sb2O3-doped SnS thin films were annealed in the hydrogen atmosphere at different temperatures and times. The structure of all the samples was characterized by X-ray diffraction (XRD). The electrical properties of SnS thin films were investigated as well. From the results, the optimum doping content of Sb2O3 was 0.2% in weight, and the resistivity of the doped-SnS film was 42Ω•cm while that of the pure-SnS film was 99Ω•cm. In addition, the film resistivity of Sb2O3-doped SnS film decreased to 24Ω•cm with the best annealing conditions of 400°C and 3 hours.

Influence of substrate temperature on properties of tin sulfide thin films

Tin sulfide (SnS) thin films for solar cells were deposited by vacuum evaporation at different substrate temperatures in a range of 20~200°C. The films were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM) for structural analysis. The electrical and optical properties were also investigated. Under the substrate temperature of 150°C, the obtained SnS thin film was in orthorhombic structure with a grain size of 0.5 μm and composition of Sn:S =1:1. The measurement results from hot probe method showed p-type nature for the deposited films. Dark-conductivity and photo-conductivity were 0.01Ω-1•cm-1 and 0.08Ω-1•cm-1, respectively. The optical band-gap energy of the films was estimated to be 1.402 eV.

Characterization of (001)-orientated polycrystalline α-HgI2 films grown by hot wall physical vapor deposition

The highly (001)-orientated α-HgI2 film was deposited by hot wall physical vapor deposition (HWPVD) technology. The scanning electron microscopy (SEM), X-ray diffraction (XRD), dark current versus applied voltage and capacitance-frequency characteristics analysis showed that the film was compactly formed by separated columnar monocrystallines with uniform orientation along c-direction and with high resistivity (2.5×1012Ω•cm) and low dark current.

Silicon nitride films as the diffusion barriers for flexible CIGS thin film solar cells

Impurity diffusion from the flexible metal substrate into CIGS absorption layer can remarkably reduce cell performance comparing with conventional glass substrate. A diffusion barrier layer lying between the metal substrate and Mo backcontact layer is required to prevent this spread of impurities. In this paper, a set of Si3+xN4-x barrier layers are grown on stainless steel sheets and alloy foils by the magnetron sputtering under different conditions. The morphological, structural and electrical properties of the samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and I-V measurements. Our results indirectly support good blocking effect of Si3+xN4-x barrier to the metal impurities from the stainless steel substrate.

Preparation of polycrystalline HgI2 films by PVD method under ultrasonic wave

Highly oriented polycrystalline α-HgI2 thick films are fabricated by physical vapor deposition method under the conditions of 59KHz ultrasonic wave and relatively lower source temperature of 80°C. The ultrasonic wave is used in the process of physical vapor deposition films preparation for the first time. With the effect of ultrasonic wave, the film quality and the growth rate can be obviously improved. The growth mechanism as well as impacts of ultrasonic wave is also discussed.

Effect of surface morphology on laser-induced crystallization of amorphous silicon thin films

The effect of surface morphology on laser-induced crystallization of hydrogenated intrinsic amorphous silicon (a-Si:H) thin films deposited by PECVD is studied in this paper. The thin films are irritated by a frequency-doubled (λ=532 nm) Nd:YAG pulsed nanosecond laser. An effective melting model is built to identify the variation of melting regime influenced by laser crystallization. Based on the experimental results, the established correlation between the grain growth characterized by AFM and the crystalline fraction (Xc) obtained from Raman spectroscopy suggests that the crystallized process form amorphous phase to polycrystalline phase. Therefore, the highest crystalline fraction (Xc) is obtained by a optimized laser energy density.

Preparation of polycrystalline silicon thin films on glass by aluminium-induced crystallization

Polycrystalline silicon (p-Si) is well-known as the high-efficency, low-cost, and most ideal material for manufacturing photovoltaic devices. In recent years, excimer-laser annealing (ELA), metal-induced crystallization (MIC) and solidphase crystallization (SPC) methods are employed to crystallize amorphous silicon (a-Si). In this paper, a cheap metal induced crystallization method of fabricating p-Si thin films on an ordinary glass substrate was investigated. In this synthesis process, a-Si thin film has been deposited onto glass substrates by Plasma Enhanced Chemical Vapor Deposition (PECVD), and p-Si thin films have been fabricated by aluminium-induced crystallization (AIC) under nitrogen ambient. The effects of annealing time, annealing temperature on the crystallization of a-Si were investigated by X-ray diffraction (XRD) technique. Our results indicate that annealing temperature over 300°C is necessary for crystallization of a-Si which preferred to orientation crystalline Si(111) and this preferred orientation becomes more obvious as increasing of annealing time and annealing temperature. Meanwhile, the longer annealing time can produce more a-Si crystallize completely under same aluminium thickness and annealing temperature.

Preparation of polycrystalline silicon thin films on glass by aluminiuminducedcrystallization

Polycrystalline silicon (p-Si) is well-known as the high-efficency, low-cost, and most ideal material for manufacturing photovoltaic devices. In recent years, excimer-laser annealing (ELA), metal-induced crystallization (MIC) and solidphase crystallization (SPC) methods are employed to crystallize amorphous silicon (a-Si). In this paper, a cheap metal induced crystallization method of fabricating p-Si thin films on an ordinary glass substrate was investigated. In this synthesis process, a-Si thin film has been deposited onto glass substrates by Plasma Enhanced Chemical Vapor Deposition (PECVD), and p-Si thin films have been fabricated by aluminium-induced crystallization (AIC) under nitrogen ambient. The effects of annealing time, annealing temperature on the crystallization of a-Si were investigated by X-ray diffraction (XRD) technique. Our results indicate that annealing temperature over 300°C is necessary for crystallization of a-Si which preferred to orientation crystalline Si(111) and this preferred orientation becomes more obvious as increasing of annealing time and annealing temperature. Meanwhile, the longer annealing time can produce more a-Si crystallize completely under same aluminium thickness and annealing temperature.

Preparation of polycrystalline silicon thin films on glass by aluminiuminduced crystallization

Polycrystalline silicon (p-Si) is well-known as the high-efficency, low-cost, and most ideal material for manufacturing photovoltaic devices. In recent years, excimer-laser annealing (ELA), metal-induced crystallization (MIC) and solidphase crystallization (SPC) methods are employed to crystallize amorphous silicon (a-Si). In this paper, a cheap metal induced crystallization method of fabricating p-Si thin films on an ordinary glass substrate was investigated. In this synthesis process, a-Si thin film has been deposited onto glass substrates by Plasma Enhanced Chemical Vapor Deposition (PECVD), and p-Si thin films have been fabricated by aluminium-induced crystallization (AIC) under nitrogen ambient. The effects of annealing time, annealing temperature on the crystallization of a-Si were investigated by X-ray diffraction (XRD) technique. Our results indicate that annealing temperature over 300°C is necessary for crystallization of a-Si which preferred to orientation crystalline Si(111) and this preferred orientation becomes more obvious as increasing of annealing time and annealing temperature. Meanwhile, the longer annealing time can produce more a-Si crystallize completely under same aluminium thickness and annealing temperature.

Preparation and optical properties of polycrystalline HgI2 thin films utilizing vertical deposition technique of chemistry

Mercuric Iodide (HgI2) is a promising semiconductor material for nuclear radiation detectors working at room temperature, especially for x-ray and γ-ray detectors. The influences of different growth temperatures on qualities of thin films were studied. The structure and optical properties of thin films were characterized by x-ray diffraction spectroscopy, metallography and UV-VIS spectrophotometer. Our results can be summarized as following: XRD analysis shows crystallinity of HgI2 in thin films depends mainly on the growth temperatures, that is, the XRD reflections become stronger with the decrease of the growth temperature. The optimum growth temperature for preparation of polycrystalline HgI2 thin film utilizing vertical deposition technique of chemistry is about 20°C. The corresponding thin film has a good uniformity with thickness of about 800 nm, perpendicular to the substrate along <001> direction. Based on its optical performance testing, our calculations found that HgI2 thin film grown at 20°C has a wide energy band gap of about 2.26 eV.