不同沉积速率下微晶硅薄膜的生长行为研究

鉴于微晶硅薄膜在沉积过程中先经历一个非晶过渡层才开始晶化的生长特点,试图通过降低薄膜的沉积速率来延长沉积原子在薄膜生长表面的扩散时间,以达到促进晶粒生长的目的。研究结果表明,反应气体气流量的减小可以有效降低薄膜的沉积速率;随着沉积速率的降低,薄膜的表面粗糙度明显减小,且其平均晶粒尺寸有所增大,通过HRTEM甚至能观察到尺寸在10nm以上的晶粒,说明沉积速率的降低对沉积粒子在薄膜生长表面的扩散过程有较大影响;另外,薄膜的少子寿命随着沉积速率的降低逐渐增大,这与薄膜结晶程度和平均晶粒尺寸的变化趋势一致,可见微观结构对电学性能起着决定作用。

Study on growth action of microcrystalline silicon thin films at different deposition rates

In view of the growth characteristics of microcrystalline silicon thin films which first undergo amorphous transition layer before crystallization, in this paper, it was attempted to prolong the diffusion time of deposited atoms on the growth surface of thin films by reducing the deposition rate of thin films, in order to promote grain growth. The results show that the deposition rate decreased with the decrease of gas flow. And as the deposition rate decreased, surface roughness decreased obviously and the average grain size improved. Grains which were bigger than 10 nm could be observed in HRTEM photos, which indicated that the decrease of the deposition rate had a great effect on the diffusion of deposited particles on growth surface. At the same time, the change rule of minority carrier lifetime agreed with the change rules of the crystallinity and average grain size, which showed a decisive effect of the microstructure on electrical properties.