利用高斯分布模型研究多晶硅晶界电学特性

Study on Electrical Property at Grain Boundary by Gauss Distribution Model in Polycrystalline Silicon

研究了多晶硅晶界的载流子输运过程和导电机制 ,建立了新的晶界结构模型和晶界势垒分布模型 .将晶界区域及其势垒的变化视为高斯分布 ,利用这个模型 ,给出了改善的电流 -电压特性方程 ,并用这个关系式来解释多晶硅的电学特性 .数值计算表明 ,多硅电阻率随势垒高度的增加而基本呈线性增加 .另外 ,电阻率 ρ随掺杂浓度的增加而减小 ,当掺杂剂浓度约为 1× 1 0 19cm-3 ,ρ和 ρgb下降最快 .且在晶粒尺寸为 1 0 2 nm范围内晶界的电阻率比晶粒的电阻率约大 2～ 3个数量级 .分析结果表明 ,晶界是高电阻区 ,晶界的这种精细分布描述 ,有助于进一步理解多晶硅的晶界特性 ,从而提高多晶硅太阳电池的光电转换效率 .

The carrier transport and conductivity mechanism in the grain boundary (GB) of polysilicon were studied, the new models about the structure and the potential barrier distribution in GB were presented. The barrier variation in GB is considered as Gauss distribution. By the models, I V equation in GB is improved and applied to explain GB electric property in the polysilicon. The calculation shows that the resistivity ( ρ ) linearly increases with increasing the barrier height. Otherwise, ρ decreases with increasing the doping concentration ( N g), ρ drop percentage is maximum at N g=1×10 19 cm -3 . Furthermore, the resistivity of GB is larger by 2～3 magnitudes than that of the grain when the grain size is about 10 2nm. The result indicates that GB is a high resistivity region and this fine description contributes to the understanding of GB property; therefore, the efficiency of the polysilicon solar cell is improved.