热原子层沉积氧化铝对硅的钝化性能及热稳定性

Passivation and stability of thermal atomic layer deposited Al_2O_3 on CZ-Si

原子层沉积氧化铝已经成为应用于钝化发射极和背面点接触(PERC)型晶硅太阳能电池优异的钝化材料.对于基于丝网印刷技术的太阳能电池,钝化材料的钝化效果及其热稳定性是非常重要的.本文在太阳能级硅片上用热原子层沉积设备制备了20nm和30nm的氧化铝,少子寿命测试结果显示初始沉积的氧化铝薄膜具有一定的钝化效果,在退火后可达到100μs以上,相当于硅表面复合速度小于100cm/s.经过制备传统晶硅太阳能电池的烧结炉后,少子寿命能够保持在烧结前的一半以上,可应用于工业PERC型电池的制备.通过电子显微镜观察到了较厚的氧化铝薄膜有气泡,解释了30nm氧化铝比20nm氧化铝钝化性能和稳定性更差的异常表现.

Atomic layer deposited （ALD） aluminum oxide （Al2O3） has been known as an almost-perfect candidate of passivation dielectric layer for PERC-type c-Si solar cell. Its passivation performance and thermal stability are key issues for industrial PERC c-Si solar cell based on screen-printed technology. In this paper, 20 nm and 30nm Al2O3 films are synthesized on the solar grade CZ-Si by thermal atomic layer deposition. The results show that the effective lifetime can reach 100 μs for CZ-Si after annealing and is kept a half after the sintering process in the industrial beltline furnace, and the materials can be used in PERC-type solar cell. The SEM image demonstrates that the blisters occur in a thicker Al2O3 film, which explains why the passivation and thermal stability of 30 nm film are inferior to those of 20 nm film.