衬底和退火温度对多晶硅薄膜结构及光学性质影响

Effect of substrate and annealing temperature on the structure and optical properties of polycrystalline silicon films

通过射频等离子体增强化学气相沉积(RF-PECVD)技术与退火处理制备多晶硅薄膜,研究了衬底和退火温度对所制薄膜的结构及光学性质的影响。本次试验最大的晶粒尺寸是在衬底温度为250℃获得,考虑薄膜表面的质量,最佳的退火温度为635℃,衬底温度为225℃,在玻璃衬底形成的晶粒大于50 nm,光学带隙为1.5 e V。结果表明:衬底温度影响着薄膜中氢含量以及相关的缺陷。随着退火温度的升高,晶化率的提高,光学带隙先减小后增大。

Polycrystalline silicon thin films were prepared by radio frequency plasma enhanced chemical vapor deposition （RF-PECVD）with additional annealing treatment. The influence of substrate temperature and annealing temperature on the structure and optical properties of silicon thin films were investigated. The experimental results show that the largest grain size is obtained with annealing temperature of 635℃ and substrate temperature of 250℃. But considering the film surface quality, the optimal substrate temperature is 225℃. On this condition, the grain size of polycrystalline silicon is more than 50 nm, and band gap is 1.5 eV with glass substrate. And the substrate temperature has an important impact on the hydrogen content in thin films and related film defects. With the annealing temperature increasing, the crystalline volume fraction increases, and the optical band gap decreases firstly and increases subsequently.