相变区纳米硅氧薄膜的微观结构及光学特性

Microstructure and optical characteristics of nanocrystalline silicon oxide film in phase transformation zone

为了研究硅异质结太阳电池中纳米硅氧薄膜的光电特性,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不同晶态比例的nc-SiOx∶H薄膜,利用拉曼散射光谱(Raman)、傅里叶变换红外光谱(FTIR)、紫外可见透射光谱以及稳/瞬态光致发光谱等检测手段分别对薄膜的微观结构、键合配置,能带特征以及发光特性进行了表征。薄膜结构特征分析显示,随着氧掺入量的增加,薄膜由微晶向非晶转化,光学带隙逐渐增加,而处在相变区(晶化度约为10%,nc-Si尺寸约为3nm)的薄膜具有较高的中程有序度、较小的结构因子和较为致密的微观结构。薄膜稳/瞬态光致发光结果显示,一定量的氧掺入可以钝化缺陷、增强发光,而相变区薄膜的发光强度最大,表明较小尺寸的nc-Si具有较强的量子限制效应,nc-Si的量子限制效应发光是主要的载流子复合机制。

A series of nc-SiOx ＂ H films were prepared by Very High Frequency Plasma Enhanced Chemical Vapor Deposition （VHF-PECVD）, for the properties study of nanocrystalline silicon oxide films in silicon heterojunction solar cells. The microstructure, bonding configuration, band character- istics and photoluminescence properties of the films were characterized by Raman scattering spectra （Raman）, Fourier transform infrared spectra （FTIR）, UV-VIs transmission spectra and steady/tran- sient state photoluminescence spectra （PL）, respectively. Raman analysis shows that the film struc- ture changes from microcrystalline to amorphous with the increasing of oxygen content. The films proves to have better ordered and denser structure in the phase transformation zone, where the crys- tallization degree is about 10% and nc-Si particles is about 3 nm. The steady/transient photolumines- cence （PL） analysis shows that certain amount of oxygen could passivate defects, thus enhancing thephotoluminescence. The highest luminescence intensity was zone. It indicated that stronger quantum confinement effect PL should be the main carrier recombination mechanism. achieved in the phase transformation induced by the smaller nc-Si particles