氢氦共同稀释对微晶硅锗薄膜结构特性的影响

Influence of Helium and Hydrogen Mixture Dilution on the Structural Properties of Microcrystalline Silicon-germanium Films

采用射频等离子体增强化学气相沉积(RF-PECVD)技术,在200℃的衬底温度下,以SiH4和GeH4为反应气体,H2和He为稀释气体,制备微晶硅锗(μc-Si1-x Ge x∶H)薄膜。结合Raman,XRF,FTIR,AFM等测试,我们分析了不同流量He的掺入对高锗含量(Ge含量～40%)μc-Si1-x Ge x∶H薄膜结构性能和光电特性的影响。结果表明,随着He稀释/H2稀释(C He/H2=He/H2)的增加,薄膜的Ge含量基本保持不变,H含量减少,致密度提高,Ge悬挂键和微结构因子先减少后增大。C He/H2=36%时,薄膜光电特性最好。

Hydrogenated microcrystalline silicon-germanium films（ μc-Si1-xGex： H） were prepared by radio frequency plasma-enhanced chemical vapor deposition（RF-PECVD） using S1H4-GeH4 gas mixture at the growth temperature of 200 ℃. The effect of helium and hydrogen dilution on the film photoelectric and structural properties of μc-Si1-xGex： H were studied. As the He flow rate increasing, the H contents of the films decreased while Ge contents keep constant. The FFIR, XRD, AFM and photo/dark conductivity measurements together indicated that high quality μc-Si1-xGex： H thin film with dense micro-structure, low defect states density and optimum optoelectronic property is achieved with a helium and hydrogen dilution ratio of 36%. The possible effects of helium dilution on the growth process and properties of μc-Si1-xGex：H thin film were discussed. Key words： microcrystalline silicon-germanium film ; PECVD ; helium dilution