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对氢化纳米硅薄膜中氢的键合特征和薄膜能带结构之间的关系进行了研究.所用样品采用螺旋波等离子体化学气相沉积技术制备,利用Raman散射、红外吸收和光学吸收技术对薄膜的微观结构、氢的键合特征以及能带结构特性进行了分析.Raman结果显示不同衬底温度下所生长薄膜的微观结构存在显著差异,从非晶硅到纳米晶硅转化的衬底温度阈值为200℃.薄膜中氢的键合特征与薄膜的能带结构密切相关.氢化非晶硅薄膜具有较高的氢含量,因键合氢引起的价带化学位移和低衬底温度决定的结构无序性,使薄膜呈现较大的光学带隙和带尾宽度.升高衬底温度主要导致氢化纳米硅薄膜中纳米硅界面的键合氢含量增加,使薄膜光学带隙和带尾宽度呈减小趋势,该结果主要关联于键合氢对纳米晶粒表面悬键的中止作用.对应更高的衬底温度,因薄膜中的氢不能完全中止纳米晶粒界面的悬键,使薄膜能带带尾加宽.
The relationship between the bonding characteristics of hydrogen and the band structure of the films in hydrogenated nano-silicon films was studied.The samples were prepared by spiral-wave plasma chemical vapor deposition (PLVD), Raman scattering, infrared absorption and optical absorption Microstructure, hydrogen bonding characteristics and band structure properties were analyzed.Raman results show that the microstructure of the films grown at different substrate temperatures are significantly different, the substrate temperature from amorphous silicon to nanocrystalline silicon conversion threshold is 200 ℃ .The bonding characteristics of hydrogen in the film are closely related to the band structure of the film.The hydrogenated amorphous silicon thin films have high hydrogen content and the structure determined by chemical shifts of the valence band due to the bonding hydrogen and the low substrate temperature Order, so that the film showed a larger optical band gap and tail width.High substrate temperature led to the hydrogenation of nano-silicon nano-silicon interface in the hydrogen bonding hydrogen content increased, the film optical band gap and tail width decreased This trend is mainly associated with the abrogation of the dangling bond of the bonded hydrogen to the surface of the nanocrystalline grains. Corresponding to the higher substrate temperature, the nanocrystalline grains can not be completely stopped due to the hydrogen in the film Dangling bond of the surface, the film can widen the band tail.