金属诱导垂直生长低温Poly-Si1-xGex(0≤x≤0.2)薄膜及其作为太阳能电池材料特性研究

As we know, metal-induced crystallization can crystallize amorphous Si and SiGe thin films at low temperature (≤500 ℃). And this technology is compatible with conventional semiconductor process, which is large-area, low-cost method. But crystalline Si and SiGe thin films have grain boundaries which represent one of the most significant problems,and have metal contamination. Based on the above problem, this work is aimed at studying the metal-induced vertical growth to produce device quality poly-Si and SiGe thin films with by applying metal silicide as seed layers, which has larger grain size, less grain boundaries and a lower metal contamination.Considering that crystalline SiGe thin films have high absorption coefficient (especially in the long wavelength absorption) and adjustable bandgap, we will fabricate poly-Si and SiGe thin film solar cell using metal silicide　as seed layer, which is expected to eliminate the grain boundaries in the vertical direction (carrier transport direction) and reduce metal contamination.Combining computer simulation and experimental results, metal-induced crystallization mechanism will be summarized, and the influence of process parameters on the performance of materials and devices will be studied, which will provide optimum process parameters for the preparation of low-temperature poly Si and SiGe thin films and devices.

金属诱导晶化技术可在较低温度（≤500 ℃）使得非晶硅、硅锗薄膜晶化，并与传统的半导体工艺兼容,可批量低成本生产，但制备的多晶硅、硅锗薄膜中存在较多的晶粒间界，光生少子在晶粒间界处复合使得光电流损失，以及存在金属污染等问题。本项目针对以上问题，结合硅锗合金高吸收系数，尤其能够有效增加对长波段吸收，以及禁带宽度可调和光谱响应范围可拓宽等特点，拟采用金属硅化物作为籽晶层垂直外延生长晶粒尺寸大,晶粒间界少,金属含量低的具有优异光电性能的低温poly-Si1-xGex（0≤x≤0.2）薄膜，减少薄膜中的金属污染,并在垂直方向（载流子传输方向）消除晶粒间界，将制备的多晶硅、硅锗薄膜作为薄膜太阳能电池材料，有望提高电池的转换效率；通过计算机模拟并结合实验结果总结金属诱导晶化机理，研究清楚工艺参数对材料和器件性能的影响，为制备低温多晶硅、硅锗薄膜和器件提供最佳工艺参数。

金属诱导晶化技术制备的多晶硅薄膜中，存在较多的晶粒间界，光生少子在晶粒间界处复合使得光电流损失，以及存在金属污染等，这些问题使得多晶硅薄膜太阳能电池的转换效率较低。本项目拟采用金属硅化物作为籽晶层垂直生长具有器件质量的低温poly-Si1-xGex薄膜，在减少金属污染的同时在垂直方向（载流子传输方向）消除晶粒间界。并将制备的多晶硅锗薄膜作为电池材料制备了PIN结构薄膜太阳能电池，系统地研究了工艺参数对电池开路电压、短路电流和填充因子等的影响；总结了金属诱导晶化机理，从理论上弄清楚了具体的金属诱导过程，以及工艺参数对薄膜和器件性能的影响，阐明了金属诱导晶化机理等科学问题，为工业化大规模制备高转换效率的多晶硅薄膜太阳能电池提供了理论指导和工艺参数参考。相关的成果转换部分正在商谈中。