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Ye F.,Dalian University of Technology | Xu F.F.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province
Materials Research Innovations | Year: 2015

Boron and oxygen are major non-metallic impurities in silicon, and they often exist in the form of boron and oxygen (B-O) pair, which plays an important role in silicon and can induce the silicon-based solar cell suffering a light-induced-degradation in efficiency up to 1-2%. In this work, the ab initio calculations based on the density functional theory (DFT) are carried out to understand the effect of silicon environment on B-O bonding state by comparing the states in vacuum, oxide, and silicon. It has been found out that the contribution of 2s and 2p orbitals of oxygen to the bonding state is always higher than those of the boron. Moreover, because the B-O spacing in silicon is larger, the electronic density of states (DOS) B and O are decreased by the bonding with the silicon atoms, and the bonding strength of B-O pair in silicon is lower than those in boron oxide and vacuum. The decrease in the DOS and the bonding strength is also supported by the fact that the atomic population is also decreased by the silicon environment. © W. S. Maney & Son Ltd 2015.


Shi W.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | Shi W.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | Tan Y.,Dalian University of Technology | And 2 more authors.
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2013

With pre-oxidized fiber integrated felt prepared by relayed needle punching process as preform and thermosetting resin as precursor, impregnation-curing-carbonization of resin-graphitization process was employed to prepare rigid carbon fiber integrated felt used for thermal insulation. Effect of every process including needle punching parameters, carbonization temperature, solution concentration and curing pressure on density was studied. Microstructure of samples was studied by using SEM. The results show that high values of needle-punching parameters lead to high values of preform density, carbonization temperature has little influence on density, but much influence on carbon content. Also solution concentration and preform density have a certain influence on density. What is more, with increasing curing pressure, the density of samples increases.


Sun S.H.,Dalian University of Technology | Sun S.H.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | Tan Y.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | And 5 more authors.
Journal of Materials Engineering and Performance | Year: 2012

The effects of impurities on the resistivity distribution and polarity of multicrystalline silicon ingot prepared by directional solidification were investigated in this article. The shape of the equivalence line of the resistivity in the vertical and cross sections was determined by the solid-liquid interface. Along the solidification height of silicon ingot, the conductive type changed from p-type in the lower part of the silicon ingot to n-type in the upper part of the silicon ingot. The resistivity in the vertical section of the silicon ingot initially increased along the height of the solidified part, and reached its maximum at the polarity transition position, then decreased rapidly along the height of solidified part and approached zero on the top of the ingot because of the accumulation of impurities. The variation of resistivity in the vertical section of the ingot has been proven to be deeply relevant to the distribution of Al, B, and P in the growth direction of solidification. © 2011 ASM International.


Li Y.,Dalian University of Technology | Li Y.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | Tan Y.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | And 5 more authors.
Journal of Alloys and Compounds | Year: 2014

Si-Al and Si-Al-Sn alloy melts were used for silicon purification by alloy solidification refining method. The effects of Sn addition on alloy microstructure, eutectic Si morphology, as well as B distribution were investigated using optical microscopy, scanning electron microscopy, electron probe microanalyzer and inductively coupled plasma mass spectrometer. Primary Si and αAl + Si structures with flake-like eutectic Si were found in Si-Al alloy; while an additional structure of αAl + βSn + Si in Si-Al-Sn alloy was found. Si in αAl + Si eutectic had a globular shape, whereas some Si in αAl + βSn + Si eutectic had an octahedral shape. Compared with primary Si, more boron was found to distribute in final solidified phase during the solidification, i.e. αAl + Si for Si-Al system and αAl + βSn + Si for Si-Al-Sn system. The refining ratio of B decreased with increasing Al content in Si-Al alloy melt, while increased with Sn addition using Si-Al-Sn alloy melt. © 2013 Elsevier B.V. All rights reserved.


Tan Y.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | Guo X.,Dalian University of Technology | Guo X.,Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province | And 6 more authors.
Vacuum | Year: 2013

According to the traditional metallurgical theory, the evaporation process of phosphorus and silicon during silicon refining by electron beam melting (EBM) is discussed and a theoretical model is established to obtain the loss rate of silicon, the removal efficiency of phosphorus and the corresponding energy consumption. The results show that phosphorus can be removed from silicon melt efficiently and quickly by EBM. There is a one-to-one correspondence between the loss of silicon and the removal efficiency of phosphorus, indicating that they have obvious effect on each other, whereas the EB power has little influence on the loss rate of silicon. If the EB power is increased from 9 kW to 21 kW, the melting time can be shortened by 68%, the loss of silicon increased by only 0.1% and the energy consumption decreased by 25%. Based on the theoretical and experimental results, a high-power EBM method is considered to be a better way for the removal of phosphorus with high efficiency and low energy consumption under such experiment conditions. © 2013 Elsevier Ltd. All rights reserved.

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