锗烷浓度对非晶/微晶相变区硅锗薄膜结构及光电特性的影响

摘要

Several series of silicon-germanium alloy films were prepared by very high frequency plasma enhanced chemical vapor deposition with various germane concentrations.The influence of germane concentration on the microstructure and optoelectronic properties of silicon-germanium alloy films at transition and transition edge regime was studied.It was found that Ge suppressed the growth of crystalline silicon and the transition from microcrystalline to amorphous took place with the increase of germane concentration.The silicon-germanium alloy films at transition regime were rich silicon alloys,of which the microstructures were nanocrystalline silicon embedded in the amorphous silicon-germanium alloy matrix.The optical gap Eoo decreased,but structure factor F,as a means of quantifying the amount of microstructure,lessened at first,then went up with increasing of germane concentration.The silicon-germanium alloy fdm on the transition edge was most compact,of which the photosensitivity approached 104,which was suitable for the intrinsic layer of tandem solar cell when germane concentration was 9％.%采用甚高频等离子体增强化学气相沉积技术,制备了一系列从非晶到微晶相变区硅锗合金薄膜,研究了锗烷浓度对相变区及相变边缘硅锗薄膜微观结构和光电特性的影响.结果表明,锗烷的加入抑制了晶态硅的生长,使硅锗合金薄膜发生从晶态到非晶结构的转变.相变区硅锗薄膜为富硅合金薄膜,表现为纳米硅晶粒镶嵌于非晶硅锗网络的微观结构.随着锗烷浓度增加,合金薄膜光学带隙Eopt逐渐减小,表征薄膜结构有序性的结构因子F,呈先减小后增加趋势.当锗烷浓度为9％时,硅锗合金薄膜处在非晶/微晶相变边缘,薄膜具有较高的致密性,光敏性接近104,适用于叠层薄膜太阳能电池器件吸光层应用.