ECR-PECVD制备纳米硅颗粒薄膜

Nano-silicon films prepared by ECR-PECVD

为消除紫外线对硅基薄膜太阳能电池的热损害,并进一步提高电池转换效率,提出在硅基薄膜太阳能电池顶部低温下制备一薄层纳米硅薄膜.在P型（100）硅片上采用电子回旋共振微波等离子体增强化学气相沉积（ECR-PECVD）技术交替沉积SiO2/Si/SiO2层,改变衬底温度和H2流量沉积纳米硅薄膜,探讨低温下直接制备纳米硅薄膜的工艺.实验结果表明,在低温下,薄膜以非晶相为主,局部分布有零星的网格状晶化相,随着温度的升高,晶化趋势增加,晶化相颗粒大小在5~8 nm;当H2流量在20~40 mL/min变化时,随着流量的增加,薄膜晶化相增多,纳米硅尺寸在5~10 nm,但H2流量超过30 mL/min后,随着H2流量的增加,薄膜晶化率下降,纳米硅颗粒减少.利用H等离子体原位刻蚀方法,可明显改善薄膜晶化效果,经原位刻蚀处理后纳米晶颗粒尺寸及分布比较均匀,颗粒大小在6 nm左右.

In order to reduce the thermal damage of ultraviolet rays and also for further increase in the efficiency of the silicon-based thin film solar cells,a nano-silicon thin film was prepared on the top of the cells at low temperature.The SiO2/Si/SiO2 multilayers were deposited alternately on the p-type silicon substrate by electron cyclotron resonance(ECR-PECVD).The microstructure of the films was investigated by TEM.The results show that the silicon film is mainly amorphous with locally distributed latticed crystalline phase at low temperature,and with the increase of the temperature the tendency of crystallinity increases and the size of the crystalline is about 5-8 nm.When the flow rate of H2 is changed from 20 mL/min to 40 mL/min,the crystallinity of the nano-silicon increases,and the size of nano-Si particles is about 5-10 nm.But when the flow rate exceeds 30 mL/min,the crystallinity of the films decreases and the number of nano-Si particles reduces.In order to improve the crystallinity of the films,the silicon film was in-situ etched by hydrogen plasma after deposition.The TEM result shows that the amounts of the nano-silicon particles are noticeably increased,the size and distribution of the particles are homogeneous,and the particle size is about 6 nm.