Evolution of a Native Oxide Layer at the a-Si:H/c-Si Interface and Its Influence on a Silicon Heterojunction Solar Cell

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• 作者：Wenzhu Liu ; Fanying Meng ; Xiaoyu Zhang ; Zhengxin Liu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：7
• 期：48
• 页码：26522-26529
• 全文大小：449K
• ISSN：1944-8252

文摘

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 (鈭?0 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 鈭?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.