摘要
薄层a-Si∶H钝化技术对于提高硅异质结太阳能电池的效率至关重要,通常有三类工艺可显著改善a-Si∶H薄膜的钝化效果:晶硅表面湿化学处理(薄膜沉积前);氢等离子体处理(薄膜沉积过程中);后退火处理(薄膜沉积后)。该论文基于等离子增强型化学气相沉积系统,采用氢等离子处理和后退火处理改善a-Si∶H/c-Si界面的钝化效果,样品的有效少数载流子寿命最高达到1 ms,并研究了射频功率密度、腔体压力、氢气流量等工艺参数对钝化效果的影响;采用光发射谱、台阶仪等对氢等离子体处理所涉及的物理过程进行研究,得出该工艺对a-Si∶H薄膜具有刻蚀作用;根据钝化效果和刻蚀速率的关系,得出低刻蚀速率由于给予薄膜充足的时间进行结构弛豫或重构,显著改善钝化效果;基于快速热退火方法进一步改善钝化效果,采用傅里叶变换红外光谱对a-Si∶H薄膜的钝化机理进行研究,并基于化学退火模型进行讨论;采用透射电镜研究了a-Si∶H/c-Si界面的微结构,并没有观测到影响钝化效果的外延生长。
Hydrogenated amorphous silicon(a-Si∶H)films play a key role in increasing the efficiency of silicon heterojunction solar cells(SHJ).Usually there are three kinds of processing technology that apparently improve the passivation quality of a-Si∶H films,which contain chemical treatment of c-Si surface(before a-Si∶H deposition),hydrogen plasma treatment(during a-Si∶H deposition)and post-annealing process(after a-Si∶H depostion).Based on a plasma enhanced chemical vapor deposition system,this paper employs hydrogen plasma treatment and post annealing process to improve a-Si∶H/c-Si interface passivation quality obviously,and the highest effective minority carrier lifetime of samples has reached at 1 ms.The influence of experimental parameters(power density,reactor pressure,the H 2 flow)on passivation quality is also studied.Optical emission spectroscopy and profile are used to investigate the concerning process of hydrogen plasma treatment is studied and this treatment will etch a-Si∶H films.The relationship between passivation quality and etching rate indicates that at slow etching rate the network of a-Si∶H films has enough time to proceed structural relaxation or reconstruction,which will apparently improve passivation qualiy.Rapid thermal process is employed to induce a further improvement of passivation quality,Fourier Transform Infrared Spectrometer is used to analyze the passivation mechanism and it is discussed based on the chemical annealing model.The microstctrure of a-Si∶H/c-Si interface is studied by transmission electron microscopy and no epitaxial growth exists at interface.
作者
王楠
钟奇
周玉琴
WANG Nan;ZHONG Qi;ZHOU Yu-qin(Silicon Epitaxy Department,China Electronics Technology Group Corporation No.46 Institute,Tianjin 300220,China;Shanghai Multiple Films&Laser Tech.Co.,Ltd.,Shanghai 201306,China;College of Materials Science and Opto-Electronic Technology,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《人工晶体学报》
EI
CAS
北大核心
2019年第10期1912-1919,共8页
Journal of Synthetic Crystals
基金
国家重点基础研究发展计划(973)项目(2011CBA00705)
天津市自然科学基金(18JCYBJC41800)
天津市科技计划项目(18ZXJMTG00300)
