title: Evolution of a Native Oxide Layer at the a-Si:H/c-Si Interface and Its Influence on a Silicon Heterojunction Solar Cell.
abstract: The interface microstructure of a silicon heterojunction (SHJ) solar cell was investigated. We found an ultrathin native oxide layer (NOL) with a thickness of several angstroms was formed on the crystalline silicon (c-Si) surface in a very short time (∼30 s) after being etched by HF solution. Although the NOL had a loose structure with defects that are detrimental for surface passivation, it acted as a barrier to restrain the epitaxial growth of hydrogenated amorphous silicon (a-Si:H) during the plasma-enhanced chemical vapor deposition (PECVD). The microstructure change of the NOL during the PECVD deposition of a-Si:H layers with different conditions and under different H2 plasma treatments were systemically investigated in detail. When a brief H2 plasma was applied to treat the a-Si:H layer after the PECVD deposition, interstitial oxygen and small-size SiO2 precipitates were transformed to hydrogenated amorphous silicon suboxide alloy (a-SiO(x):H, x ∼ 1.5). In the meantime, the interface defect density was reduced by about 50%, and the parameters of the SHJ solar cell were improved due to the post H2 plasma treatment.
authors.affiliation: Research Center for New Energy Technology, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS) , Jiading, 201800 Shanghai, People's Republic of China.|University of Chinese Academy of Sciences (UCAS) , Shijingshan, 100049 Beijing, People's Republic of China.
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Liu
authors.affiliation: Research Center for New Energy Technology, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS) , Jiading, 201800 Shanghai, People's Republic of China.
authors.forename: Fanying
authors.initials: F
authors.lastname: Meng
authors.affiliation: Research Center for New Energy Technology, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS) , Jiading, 201800 Shanghai, People's Republic of China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Research Center for New Energy Technology, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS) , Jiading, 201800 Shanghai, People's Republic of China.
authors.forename: Zhengxin
authors.initials: Z
authors.lastname: Liu
keywords: H2 plasma; epitaxial growth barrier; microstructural evolution; native oxide layer; surface passivation