一种新的补偿硅电阻率/掺杂浓度模型

摘要

硅片或硅块的电阻率与掺杂浓度的关系模型不适用于补偿硅,如精纯冶金级硅(UMG-Si).目前尚无合适的理论模型可以准确解释补偿硅实验和观测结果间存在的差异.基于电解液理论提出一种包含电离平衡常数的新方法,可以得到单掺杂硅的电荷载子迁移率Thurber曲线.当掺杂硅中包含一种以上掺杂物质时,需要采用数值算法来解决多重平衡系统.研究表明这类系统表现出一种缓冲溶液的特定行为.通过计算化合物的热力学参数获得平衡常数,并利用现有的电化学知识(Nerust方程和Butler-Volmer方程)提出一个普遍理论.因为硅/掺杂物系统构成一个弱电解质固溶体,电解质溶液理论为太阳能电池行为的认知提供了一个很好的物理模型和数学框架.%Models establishing relationships between electrical resistivity and dopant densities of silicon wafers/bricks are not applicable for compensated-Si, such as upgraded metallurgical grade silicon UMG-Si. To date, no satisfactory theoretical model has been able to explain precisely the variety of new experimental results and observations related to compensated-Si. In this study, a new approach considering equilibrium ionisation constants according to electrolyte theory was proposed, which reproduce, for single-doped Si, Thurber's curves of charge carrier's mobilities. When more than one doping species are involved, as in compensated-Si, a numerical algorithm has to be used for solving multiple equilibrium systems. The study of such systems demonstrates a particular behaviour known from buffered solutions. Equilibrium constants were calculated from thermodynamic properties of chemical compounds, and a new general theory was proposed using available knowledge of electrochemistry (Nernst equation, Butler-Volmer equation). Considering that the silicon/dopant systems constitute a weak electrolyte solid solution, it is concluded that the electrolyte solution theory provides a good physical model and mathematical framework to get a better understanding of solar cell's behaviour.