铸造多晶硅论文：铸造多晶硅位错及其热处理消除研究.doc

铸造多晶硅论文：铸造多晶硅位错及其热处理消除研究【中文摘要】目前在太阳能电池生产领域中,铸造多晶硅电池占有主导地位,但是其内部存在的高密度位错和晶界严重影响其电学性能,从而影响多晶硅太阳电池的能量转换效率。本文报告我们就铸造多晶硅内部位错及其热处理消除技术开展的基础研究工作,以期为减少多晶硅内部位错、提高多晶硅太阳电池的转换效率提供参考。本文主要内容包括：研究铸造多晶硅内部位错密度的大小、分布以及位错对多晶硅材料电学性能的影响；高温退火的温度和降温速率对铸造多晶硅片(厚度1Omm)内部位错密度的影响研究。研究结果表明：实验所用铸造多晶硅内部的位错密度基本都处在105/cm2量级,而且位错密度从硅锭底部到顶部呈现逐渐降低的趋势,同时发现位错确实是影响材料电学性能的重要因素之一,即位错密度高的区域,少数载流子的寿命低,反之亦然。对铸造多晶硅片进行10001400的高温退火实验发现,多晶硅片经过1320及以上温度高温退火并缓慢冷却(降温速率7/min)处理后,其内部的位错密度会显著下降,当退火温度达到1340时,其内部的位错密度可降低51.7%。但是研究也发现,铸造多晶硅块经过1340高温退火并以2/min的降温速度缓慢冷却处理后,多晶硅块内部的位错密度并没有降低,反而有一定程度的升高。文中结合计算模拟分析对实验结果及其生产实践参考价值进行了讨论。【英文摘要】Multicrystalline silicon cells predominate in solar cell industry, High-density dislocations and grain boundaries play an important role in influencing the electrical and photovoltaic properties of mc-Si solar cells. In this paper we report on dislocation in casting multicrystalline silicon and its eliminating by heating treatment. It can be expected to reduce the dislocations of silicon. Consequently, the technology can improve the conversion efficiency of polycrystalline silicon cells.The main contents include:The dislocation density and dislocation distribution of cast multicrystalline silicon; the effect of dislocation on the electrical properties of multicrystalline silicon; the influence of annealing temperature and cooling method on the dislocation density in silicon wafers (thickness10mm). The results show that:the dislocation density of casting multicrystalline silicon was about 105/cm, and the dislocation density of silicon ingot from the bottom to the top showed a decreasing trend. We also found that the dislocation is one of the important influencing factors on electrical properties of materials. Namely, in the areas of high dislocation density, the minority carrier lifetime was low, and vice versa. High temperature annealing at 10001400and various subsequent cooling experiments for multicrystalline silicon wafers have been carried out. We found that the wafers were annealed at 1320or at higher temperature, and then cooled slowly (cooling rate7/min), the dislocation density of the wafers decreased remarkably, when the annealing temperature reached to 1340, the dislocation density of silicon wafers could be reduced 51.7%. But we also found that the dislocation density of silicon bricks increased when the bricks were annealed at 1340and cooled slowly (cooling rate was 2/min). Combing computational simulation and analysis, this paper discussed the experimental results and its reference value of productive practice.【关键词】铸造多晶硅 硅片 硅块 高温退火 位错密度【英文关键词】casting multicrystalline silicon silicon wafer silicon brick high temperature annealing dislocation density【目录】铸造多晶硅位错及其热处理消除研究摘要3-4ABSTRACT4第一章 绪论7-201.1 太阳能光伏产业的发展背景及前景7-91.2 太阳能电池发电原理9-101.3 光伏产业的发展与多晶硅电池的主导地位10-141.3.1 光伏产业的发展10-131.3.2 多晶硅电池的主导地位13-141.4 铸造多晶硅生产技术14-151.5 铸造多晶硅锭中的位错及热过程影响研究15-191.5.1 铸造多晶硅中的杂质和位错15-171.5.2 铸造多晶硅中位错热处理消除技术17-191.6 本论文的研究目的和主要研究内容19-20第二章 铸造多晶硅内部位错及其对电学性能的影响20-292.1 引言202.2 实验方法20-212.2.1 材料试样202.2.2 仪器与试剂20-212.2.3 实验步骤212.3 结果与讨论21-272.4 本章小结27-29第三章 高温退火对铸造多晶硅片中位错密度的影响29-383.1 引言293.2 实验方法29-323.2.1 材料与试样29-303.2.2 仪器303.2.3 实验过程30-323.3 结果与讨论32-373.3.1 退火温度对硅片中位错密度的影响32-353.3.2 退火后冷却方式对硅片中位错密度的影响35-373.4 本章小结37-38第四章 高温退火对铸造多晶硅块中位错密度的影响38-454.1 引言384.2 实验方法38-394.2.1 材料与试样384.2.2 仪器384