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1.
The microstructure and minority carrier lifetime of silicon were investigated in uniaxially compressed silicon samples. The objective of the investigation was to determine if it is feasible to produce silicon solar cells from sheet formed by high temperature deformation. The initial structure of the silicon samples ranged from single crystal to fine grained polycrystals. The samples had been deformed at strain-rates of 0.1 to 8.5 s−1 and temperatures of 1270 to 1380°C. Recrystallization was incomplete even after long anneals. A 10 h anneal of fine grained samples with as much as 51 pct strain only caused 95 pct of the samples to recrystallize and even then the recrystallized grains contained twin boundaries and dislocations. The recrystallization in the large grained material was also incomplete and further, it has been shown that large grained material cracks readily during significant deformation (>40 pct). The major mode of recrystallization appears to be migration of existing boundaries into the deformed regions. Minority carrier diffusion length was found to be drastically reduced after deformation, perhaps due to contamination or cooling rate, and recovered only slightly with annealing. These results suggest that high temperature deformation, of silicon to directly produce sheet for solar cells of high efficiency is not practical. Potential may exist for its use as a coarse grained substrate.  相似文献   

2.
Preparation of pure silicon by electrowinning in a bytownite-cryolite melt   总被引:1,自引:0,他引:1  
Pure silicon was prepared by electrowinning in a bytownite-cryolite molten mixture at about 970 °C. In the electrolysis cell, the bottom of a graphite crucible was used as the anode. The cathode was also made of graphite. The reaction was carried out at the cell voltage of about 2.7 V, and the cathode current density was either 0.027 or 0.053 A/cm2 for 10, 50, and 100 pct of the time for all Si deposited. The obtained silicon, which was analyzed by electron microprobe analysis (EMPA), contained 99.79 to 99.98 pct Si, which is a specially pure quality. CO2 gas formed at the anode flushed silicon deposited at the cathode and purified it by oxidizing the impurities that ordinarily would be deposited at the cathode.  相似文献   

3.
The activity coefficient of B in a Si melt and the interaction parameters of boron and nitrogen in molten silicon were determined by equilibrating solid BN and liquid Si in a nitrogen atmosphere from 1723 to 1923 K. The standard Gibbs free energy change of the nitrogen dissolution into silicon is also obtained. The activities of BO1.5 in the CaO-CaF2-SiO2 and CaO-MgO-SiO2 systems are estimated in relation to the removal of boron from silicon by these fluxes. Formerly Graduate Student, Department of Metallurgy, The University of Tokyo.  相似文献   

4.
冶金法提纯太阳能级硅材料的研究进展   总被引:2,自引:0,他引:2  
分析了国内外硅材料的供应及生产状况,对太阳能级硅材料冶金法提纯工艺中的湿法精炼技术、造渣提纯技术、电子束真空提纯技术、等离子体吹气技术、定向凝固技术等进行了综述,总结了有效去除金属及B、P杂质的提纯流程,指出冶金法可能是今后提纯多晶硅的研究方向.  相似文献   

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In order to effectively remove B from Si for its use in solar cells, a process involving B removal by solidification refining of Si using a Si-Al melt with Ti addition was investigated. For clarifying the effect of Ti addition on B removal from the Si-Al melt, TiB2 solubilities in Si-64.6 at. pct Al melt at 1173 K and Si-60.0 at. pct Al melt at 1273 K were determined by measuring the equilibrium concentrations of B and Ti in the presence of TiB2 precipitates. The small solubilities of TiB2 in the Si-Al melt indicate the effective removal of B from the Si-Al melt by Ti addition. Further, solidification experiments of Si-Al alloys containing B by Ti addition were performed, and the effect of Ti addition on the solidification refining of Si with the Si-Al melt was successfully confirmed.  相似文献   

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The kinetics of unidirectional capillary infiltration of silicon melt into microporous carbon preforms has been investigated as a function of the pore morphology and melt temperature. The infiltrated specimens showed alternating bands of dark and bright regions, which corresponded to the unreacted free carbon and free silicon regions, respectively. The decrease in the infiltration front velocity for increasing infiltration distances is in qualitative agreement with the closed-form solution of capillarity-driven fluid flow through constant-cross-section cylindrical pores. However, drastic changes in the thermal response and infiltration front morphologies were observed for minute differences in the preform’s microstructure. This suggests the need for a dynamic percolation model that would account for the exothermic nature of the silicon-carbon chemical reaction and the associated pore-closing phenomenon.  相似文献   

10.
Oxidation of elements in metal melt falls into two categories, as shown from the modified Ellingham-Richardson diagram. For the first category, at which the ΔG–T lines of two reactions intersect, a concept of transition temperature has been introduced. With control of this transition temperature, blowing operation of the metal melt could be so conducted that a certain element is selectively oxidized while the other remains intact in the melt, so that separation of these elements could be accomplished. Practical application of this transition temperature is discussed with respect to Ni vs. S, Cr, V, Nb, Mn or P vs. C. For the second category with ΔG–T lines nearly parallel side by side, thermodynamic analysis has shown that selective oxidation of a certain element can also occur, but as oxidation continues, its free energy change becomes equal to that of another element, so that simultaneous oxidation of both elements takes place. This is followed by simultaneous oxidation of other elements, until the final equilibrium composition of the metal melt is attained. Examples of selective oxidation followed by simultaneous oxidation are set forth in respect to deoxidation of liquid iron with Al and Si, and the oxidizing blowing of Nb-bearing hot metal. Computer calculation of the equilibrium composition of the melt with respect to the referred elements has been made. Lastly, the role in the oxidation played by Fe, the main ingredient of the melt, is briefly discussed.  相似文献   

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介绍了光伏银浆用银粉的市场前景、技术现状和制备方法,分析了各种方法的特点,同时对银粉产业及研究存在的问题和今后努力的方向做了总结和分析。  相似文献   

13.
The production of vacuum-treated rail steel with discharge of metal containing at least 0.10% C from the electrofurnace and the addition of carbon-bearing material in the ladle at discharge is described. This technology significantly reduces the oxygen content in the steel and the presence of rows of brittle-fracturing oxides and hence permits the production of higher-quality steel.  相似文献   

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The possibility of forming bulk amorphous silicon from the undercooled liquid is analyzed by calculations of the rates for homogeneous nucleation of the amorphous and crystalline phases, the rate of heterogeneous nucleation of the crystalline phase on the liquid-amorphous interface, and the possibility of crystallization of the amorphous phase in the solid state. It appears that bulk formation of the amorphous phase may be possible in appropriately seeded millimeter-sized samples. A new lower limit for the amorphous-liquid interfacial tension is presented as well. This article is based on a presentation made in the “Structure and Properties of Bulk Amorphous Alloys” Symposium as part of the 1997 Annual Meeting of TMS at Orlando, Florida, February 10–11, 1997, under the auspices of the TMS-EMPMD/SMD Alloy Phases and MDMD Solidification Committees, the ASM-MSD Thermodynamics and Phase Equilibria, and Atomic Transport Committees, and sponsorship by the Lawrence Livermore National Laboratory and the Los Alamos National Laboratory.  相似文献   

16.
Conclusions An account is given of an investigation into the high-temperature oxidation of a silicon nitride base constructional ceramic. It is shown that the mechanism of the oxidation process for this ceramic depends on temperature. The ceramic is superior in oxidation resistance to similar materials studied earlier.Translated from Poroshkovaya Metallurgiya, No. 11(263), pp. 50–54, November, 1984.  相似文献   

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Atrial natriuretic peptide (ANP) is reported to dilate a major coronary artery in both experimental animals and humans. Spasm of a major coronary artery is the cause of variant angina pectoris and can be induced by hyperventilation. The effect of the ANP infusion on anginal attack induced by hyperventilation was studied in patients with variant angina pectoris. The study was performed in the early morning on 3 consecutive days in 11 patients with variant angina pectoris in whom the attacks were reproducibly induced by hyperventilation. On days 1 and 3 (saline solution infusion), and day 2 (ANP infusion), hyperventilation was started 14 minutes after beginning infusion of ANP (0.1 microgram/kg/min) or saline solution for 6 minutes. The attacks were induced in all 11 patients by hyperventilation on days 1 and 3. However, the attacks were not induced in any patient on day 2 of the ANP infusion. The plasma ANP level increased from 33 +/- 7 pg/ml to the peak level of 2,973 +/- 479 pg/ml (p < 0.01) at the end of the ANP infusion, and the plasma level of cyclic guanosine monophosphate (cGMP) increased from 5 +/- 1 pmol/ml to the peak level of 58 +/- 6 pmol/ml (p < 0.01) 5 minutes after the ANP infusion. The plasma levels of ANP and cGMP did not change after hyperventilation on days 1 and 3. It is concluded that the ANP infusion suppresses the attacks induced by hyperventilation in patients with variant angina pectoris, and cGMP is related to the mechanisms of suppression of the attacks.  相似文献   

20.
This paper describes the results of experimental studies to develop an electron beam technology for remelting raw silicon and further refining it in a vacuum.  相似文献   

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