热丝化学气相沉积微晶硅薄膜结构及性质研究

Study on Structures and Properties of Microcrystalline Silicon Films Prepared by Hot Wire Chemical Vapor Deposition

采用热丝化学气相沉积(HWCVD)技术,以钨丝作为热丝,在不同热丝温度和氢稀释度下,分别在玻璃和单晶硅片衬底上沉积微晶硅(μc-Si∶H)薄膜材料。对所制备的微晶硅薄膜材料使用XRD、傅里叶变换红外吸收光谱、透射谱等进行结构与性能的表征分析。结果表明,随着热丝温度升高,氢稀释度变大,薄膜呈现明显的(220)择优生长取向,晶粒尺寸逐渐增大,光学吸收边出现红移,光学带隙逐渐变小。通过优化沉积参数,在热丝温度为1577℃、氢稀释浓度为95.2%、衬底温度为350℃,沉积速率为0.6 nm/s和沉积气压8 Pa条件下,制备的微晶硅薄膜呈现出了(220)方向的高度择优生长取向,平均晶粒尺寸为146 nm,光学带隙约为1.5 eV,光电导率σp为3.2×10-6Ω-1·cm-1,暗电导率σd为8.6×10-7Ω-1·cm-1,表明制备的材料是优质微晶硅薄膜材料。

Microcrystalline silicon films were prepared by hot wire chemical vapor deposition（ HWCVD）on glass substrate and n-type monocrystalline silicon wafe with tungsten filament as hot wire. In the process of the experiments,the structures and properties of microcrystalline silicon thin films were investigated by X-ray diffraction,Fourier transform infrared spectroscopy and UV-Vis spectroscopy. The results show that the thin films preferred orientation growth（ 220）,the crystalline grain size increased gradually,the optical absorption edge moved towards red wave band and the energy band width decreased with increasing of hot wire temperature and hydrogen dilution rate. By optimizing deposition parameters,a high-quality μc-silicon thin film was obtained under conditions of 1577 ℃ hot wire temperature,95.2% hydrogen dilution rate,350 ℃ substrate temperature and 8 Pa deposition pressure. The optimizationμc-silicon thin films appear highly preferred orientation growth of（ 220）,crystalline grain size of 146 nm,energy band gap width of 1. 5 eV,photo conductivity（ σp） of 3. 2 × 10^-6Ω^-1· cm^-1,dark conductivity（ σd） of 8.6 ×10^-7Ω^-1·cm^-1and 0. 6 nm /s of high deposition rate.