太阳能电池用多晶硅薄膜的制备研究

【作者】 张宇翔；

【导师】 卢景霄；

【作者基本信息】 郑州大学 ， 凝聚态物理， 2005， 博士

【摘要】 近年来，随着可持续发展，环境保护等观念的深入人心，以及常规化石能源的日渐枯竭，太阳电池研究的主要任务转到了如何成为替代能源的方向上来。但是，基于硅片的太阳电池成本下降的空间有限，很难与常规能源相竞争。硅片成本占到太阳电池原料与能耗成本的95％以上，因此，降低太阳电池成本的主要途径之一是制造薄膜电池。本文着重研究用于太阳电池的多晶硅薄膜的制备技术。本文研究了多晶硅薄膜的制备方法，低温下快速光热退火(RPTA)和高温下陶瓷衬底上快热化学气相沉积(RTCVD)，硅膜的生长及区熔再结晶(ZMR)，用高温方式在陶瓷衬底上做了太阳电池的尝试，在高温方式下做了层转移新方式的探索。 1．等离子增强化学气相沉积(PECVD)是低温沉积硅膜的主要方法。本文的第二章中对PECVD沉积多晶硅薄膜做了研究。分析了不同沉积温度、衬底、射频功率、氢稀释比、磷掺杂等参数对多晶硅薄膜结晶状态及光电性能的影响。 2．固相晶化法(SPC)是制备大晶粒多晶硅薄膜的主要方法。本文的第三章对SPC，特别是对卤钨灯作为光源的快速光热退火(RPTA)进行了较为详细的研究。在普通的RPTA温度控制方式下，实验表明在700℃和750℃之间存在一转折区间，本文给出了解释。退火温度时间对晶化后的多晶硅薄膜的晶粒尺寸和暗电导率都有很大的影响，存在a-Si：H薄膜的最佳退火条件，本文给出了解释。沉积a-Si：H薄膜时的衬底温度越高，得到的a-Si：H薄膜越容易晶化。对快速热退火机理的初步探索：作者在纯热退火的模型的基础上，考虑了光照的影响，给出了一个简单模型，可以趋势上解释我们的实验现象。采用滤除短波光的方法实验，表明短波光作用很大。实验了脉冲快速热退火，可减少衬底承受高温的时间。采用了控制卤钨灯发光光谱范围的新实验方式，给予足够多的短波光，晶化时间缩短，晶化温度也有所降低，电导率提高。即使薄膜的温度较低(＜650℃)仍然可以实现快速晶化，本征硅膜在580℃就能晶化。和普通RPTA方式相比，晶化效率提高了几倍，本文给出的原因分析。本文通过给出了不同光照条件下的快更多还原

【Abstract】 Over years, with the concept of sustainable development and environmental protection deeply rooting among the people and gradual exhaustion of ordinary petrifaction energy sources, the main research task of solar cell focuses on how to replace the energy source. But in view of the limited reduction space upon cost of solar cell of silicon wafer, it is hard to compete with conventional energy. The cost of silicon wafer accounts for over 95% of overall costs of solar cell raw material and energy consumption. Therefore, the main way to reduce the cost of solar cell is to manufacture thin film cell. The article emphasizes the fabrication technology of polycrystalline thin films of solar cell and makes research on the preparation method of polycrystalline thin films, rapid photo-thermal annealing under low temperature (RPTA) and rapid thermal chemical vapor deposition (RTCVD) on ceramic substrate under high temperature, growth of silicon film as well as zone-melting recrystallization (ZMR), attempts of solar cell on ceramic substrate by means of high temperature and makes exploration on new method of layer transfer under high temperature.1. Plasma enhanced chemical vapor deposition (PECVD) is one of the matured and simple manipulated among the thin film deposition methods at low temperature. Chapter 2 in this article makes certain research on polycrystalline silicon thin films of PECVD and analyzes the growth principle, regularity and substrate performance of silicon thin film. The influences of deposition parameters include temperature, substrate, radio frequency power, ratio of SiH4 and doping on the crystalline and electric character was studied systematically.2 Solid Phase crystallization (SPC) is main re-crystallization techniques. Chapter 3 in this article makes certain research on Solid Phase crystallization (SPC), especially on rapid photo-thermal annealing (RPTA) technique. Two series of experiment were performed.The first series of experiment is that the light intensity is automatically adjusted to produce the predefined thermal cycle, controlled by a K-type thermocouple set on the silicon wafer. It was found that when the temperature is below 700 degrees centigrade, it is very difficult for a-Si:H thin films to crystallize. When annealing temperature is above 750 degrees centigrade, it is very ease for a-Si:H thin films to crystallize. That is to say, there exists a temperature transition field between 700 to 750 degrees centigrade. Then the crystallization condition of a-Si:H was studied thoroughly when it is above 750 degrees centigrade and below 700 degrees centigrade. The results turned out that annealing temperature and time have great influence on particle size and dark conductivity. There exists the best annealing condition of a-Si:H thin films. In addition, the influence of using conventional furnace annealing to warm up before photo-thermal annealing and the substrate temperature when a-Si:H film was deposited on the crystallization of a-Si:H thin films was also studied. It was found that to use normal high temperature stove to warm up before photo-thermal annealing is helpful to increase the size of polycrystalline silicon更多还原