沉积压力对氢化非晶硅薄膜特性的影响

The Influence of Deposition Pressure on the Properties of Hydrogenated Amorphous Silicon Thin Films

采用等离子增强化学气相沉积（PECVD）系统,以乙硅烷和氢气为气源,普通钠钙玻璃为衬底制备了氢化非晶硅（a-Si∶H）薄膜,研究了沉积压力对非晶硅薄膜的沉积速率、光学带隙以及结构因子的影响。采用台阶仪、紫外可见分光光度计、傅里叶变换红外光谱仪和扫描电子显微镜等手段分别表征了a-Si∶H薄膜的沉积速率,光学带隙、结构因子和表面形貌。结果表明：随着沉积压力的增加,沉积速率呈现先上升后下降的趋势,光学带隙不断下降。当沉积压力小于210Pa时,以SiH键存在的H原子较多,而以SiH2或SiH3等形式存在的H较少;当沉积压力大于210Pa时,以SiH2,（SiH2）n或SiH3等形式存在的H较多。通过结构因子的计算,发现沉积压力在110~210Pa的范围内沉积的薄膜质量较好。

Hydrogenated amorphous silicon（a-Si∶H）thin films on soda-lime glass substrates were deposited by plasma enhanced chemical vapor deposition（PECVD）using disilane and hydrogen as source gases.To study the influence of deposition pressure on the deposition rate,optical band gap and structure factor,a surface profilometer,an ultraviolet-visible spectrometer,a Fourier transform infrared（FTIR）spectrometer and a scanning electron microscopy（SEM）were used to characterize the deposited thin films.It is found that the deposition rate firstly increased and then decreased and the optical band gap monotonically decreased with the increasing deposition pressure.Moreover,the formation of SiH bond was preferable to the formation of SH2 or SiH3bond when the deposition pressure was less than 210 Pa,while it was opposite when the deposition pressure is higher than 210 Pa.Finally,the deposition pressure in the range of 110~210Pa was found to be more suitable for the preparation of high quality a-Si∶H thin films.