温度对RTCVD法制备多晶硅薄膜生长的影响

Effect of Temperature on Growth of Polycrystalline Silicon Thin Films Prepared via RTCVD

多晶硅薄膜太阳电池是21世纪最具发展潜力的薄膜太阳电池.如何快速、大面积、高质量地沉积多晶硅薄膜一直是多晶硅薄膜太阳电池研究中的一个核心问题.文中以SiHCl3为硅源、B2H6为掺杂气,采用先进的快热化学气相沉积法（RTCVD）制备了大晶粒的多晶硅薄膜.所制备的薄膜厚度为30～40μm,沉积速率达3～7μm/min.文中还分析了沉积温度对多晶硅薄膜生长速率及晶体微观结构的影响.结果表明：当沉积温度在900～1170℃时,平均生长速率随温度近似单调递增,此时薄膜生长由表面反应阶段控制;随着温度的升高,薄膜平均晶粒尺寸也由900℃时的不足3μm增长到1170℃时的超过30μm;温度较低时,薄膜易向[220]方向生长;温度达到1170℃时,多晶硅薄膜有向[111]方向生长的趋势.

Polycrystalline silicon （poly-Si） thin films solar cells have been one of the thin-film solar cells with the greatest development potential. In the development of poly-Si thin-film solar cells, a key point is to fast deposit large and high-quality poly-Si thin films. In this paper, poly-Si thin films with large grains were prepared via the Rapid Thermal-Chemical Vapor Deposition （RTCVD）, with SiHCl3 as the silicon source and B2H6 as the doping gas. Thin films with a thickness of 30 -40μm and a deposition rate of 3 ～ 7μm/min were thus obtained. The effect of deposition temperature on the growth rate of the film and the microstructure of the crystal was then investigated. It is concluded that, with the increase in deposition temperature from 900 to 1 170 ℃, the average growth rate approximately exhibits a monotonous increase, the average crystal size increases from less than 3μm at 900 ℃ to more than 30μm at 1 170℃, and the deposition is controlled by the surface reaction mechanism. Moreover, the poly-Si thin films tend to grow in [ 220 ] direction at low temperature while in [ 111 ] preferred orientation when the temperature reaches 1 170 ℃.