Papers by Keyword: Polycrystalline Silicon

Abstract: We report on a novel method of low pressure chemical vapor deposition of polycrystalline silicon layers used for external gettering in silicon substrate for semiconductor applications. The proposed method allowed us to produce layers of polycrystalline silicon with pre-determined residual stress. The method is based on the deposition of a multilayer system formed by two layers. The first layer is intentionally designed to have tensile stress while the second layer has compressive stress. Opposite sign of the residual stresses of the individual layers enables to pre-determine the residual stress of the gettering stack. We used scanning electron microscopy for structural characterization of the layers and intentional contamination for demonstration of the gettering properties. Residual stress of the layers was calculated from the wafer curvature.

Abstract: The inner structure and defects of the silicon panel will influence the transfer efficiency and the stability of the polycrystalline solar cells, thus the non-destructive testing of the silicon panel is very important. In this paper, a Scan Acoustic Microscopy is applied to test the inner structure of polycrystalline silicon solar panel. From the grey image of C-Scan by the microscopy, the amplitude distribution of the bottom wave generated by the interaction between the inner grains of the polycrystalline silicon and the acoustic beam can be seen clearly. Furthermore, the defects as well as their size and position can also be tested by A-Scan, B-Scan and C-Scan with high resolution and high accuracy. The experiment results show that it is a good non-destructive method to test and evaluate the quality of the inner structure of polycrystalline silicon solar panel.

Abstract: In this paper, on the basis of a large number of literature at home and abroad are summarized, we used the complete with independent intellectual property rights ultrasound wire-cutting processing machine tool to carry out machining experiment , and the ultrasonic wire cutting mechanism and process was carried out in-depth study. The results showed: compared with ordinary sawing, the cutting efficiency of applying ultrasonic action was high, its cutting force and surface roughness was small, at the same time ,used the software of ABAQUS finite element simulation analysis, and further studied on the law of electroplated diamond wire saw ultrasonic vibration cutting of composite processing technology process.

Abstract: Selected area laser-annealed polycrystalline silicon (p-Si) thin films were prepared by a 248 nm excimer laser. 1 μm thick p-Si films with grain size less than 100 nm were deposited on SiO₂ substrate by chemical vapor deposition using atmospheric pressure (APCVD). Grain sizes before and after annealing was examined by scanning electron microscopy (SEM) and the mechanism of grain growth was discussed in detail. The maximum grain size of a selected area laser-annealed p-Si film can be increased from 100 nm up to 2.9 μm on SiO₂ substrate by using appropriate laser energy densities. It indicated that silicon grains in laser-annealed regions had grown up competitively with three stages.

Abstract: The anodic aluminum oxide (AAO) templates on polycrystalline silicon substrate are studied for growth of ordered nano-dot arrays in order to fabricate the porous silicon layers. The AAO templates on polycrystalline silicon substrate with pores of average diameter 50nm were successfully prepared by one-step anodization of high pure aluminum layer deposited on polycrystalline silicon in oxalic acid solution. Scanning electron microscopy (SEM) showed that alumina nano-pore arrays were nicely constructed with smooth wall morphologies and well-defined diameters.

Abstract: Al-induced crystallization (AIC) method was used for obtaining polycrystalline silicon (poly-Si) film on glass substrate. The films with glass/a-Si:H/Al structure were fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and magnetic sputtering. Then the samples were sent to perform annealing treatments during the different temperatures and time. The experimental results demonstrate that a highly crystallized poly-Si sample can be achieved by annealing at 480°C for 2h. The crystalline fraction (Xc) of the sample is about 99.1% and the Full Width at Half Maximum (FWHM) is 4.89cm^-1. The average grain size of this sample is about 250nm. The energy dispersive spectroscopy (EDS) measurement confirms that the residual Al in the film is very little.

Abstract: Silicon thin film was successfully deposited on glass substrate using Radio frequency (RF) magnetron sputtering. The effect of deposition pressure on the physical and structural properties of thin films on the glass substrate was studied. The film thickness and deposition rate decreased with decreasing deposition pressure. Field emission scanning electron microscopy (FESEM) shows as the deposition pressure increased, the surface morphology transform from concise structured to not closely pack on the surface. Raman spectroscopy result showed that the peak was around 508 cm-1, showing that the thin film is nanocrystalline instead of polycrystalline silicon.

Abstract: The vacuum induction melting and control solidification is a new developed process for the manufacture of polycrystalline silicon with the advantage of quick heating rate compared to the traditional resistance heating method. The graphite susceptor of the induction furnace plays a key role in controlling the temperature of the melt of polycrystal silicon for solar cells. This paper investigates how different coatings painted on the susceptor would influence the heating efficiency and the temperature distribution of the silicon melt. A graphite susceptor is usually coated with a thin film of insulating material to reduce heat losses and to prevent vapors such as SiO to contaminate the susceptor. Numerical simulations show that the coating material at the outer surface of the susceptor should be the one with low thermal conductivity to prevent heat loss. On the other hand, the coating on the inner surface should be the material with high thermal conductivity to allow easy heat transfer.

Abstract: The photovoltaic (PV) industry, as the renewable energy, has discarding the traditional energy consumption and dependence mode completely, which had attracted more and more attentions of the countries all over the world. This paper analyzes the polycrystalline silicon, as the most important step of the PV industrial chain, the effects of its development on China photovoltaic industry, and forecasts the output of domestic polycrystalline silicon industry by using the grey model. According to the forecast results, proposing the relevant suggestions for the further development of PV industry in China.

Abstract: Polysilicon is an important part of forming the component of solar PV, which costs most in the total cost of PV, and is about 37% of the prime cost in grid-connected PV system. By analyzing and forecast the changes of Polysilicon prices, combined with China current situation and relevant policies on photovoltaic power generation, to make some suggestions for the development of China solar photovoltaic industry