Control of micro void fraction and optical band gap in intrinsic amorphous silicon thin films (VHF-PECVD) for thin film solar cell application
| Autor: | Junsin Yi, Chonghoon Shin, Junhee Jung, Jinjoo Park, Sangho Kim, Youn-Jung Lee, Sungjae Bong |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Amorphous silicon
Materials science Hydrogen Passivation Band gap Plasma parameters Mechanical Engineering Analytical chemistry chemistry.chemical_element Substrate (electronics) Condensed Matter Physics chemistry.chemical_compound chemistry Mechanics of Materials Plasma-enhanced chemical vapor deposition General Materials Science Thin film |
| Zdroj: | Materials Research Bulletin. 60:895-899 |
| ISSN: | 0025-5408 |
| DOI: | 10.1016/j.materresbull.2014.09.019 |
| Popis: | Plasma parameters are important factors for fabricating intrinsic (i-type) layers of hydrogenated amorphous silicon (a-Si:H) films using a very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) system. In this work, the effects of hydrogen ratio (R), power density, pressure, electrode instances ( E d ) and substrate temperature ( T s ) on the growth and the properties of intrinsic amorphous silicon (i-type a-Si:H) thin films are investigated. The structural defect (micro void fraction: R *) and optical band gap ( E g ) can be controlled by changing the plasma conditions. High quality i-type a-Si:H is obtained with low power, pressure, moderate hydrogen ratio (R&9552;H 2 /SiH 4 : 4) and short electrode distance conditions at which a lot of SiH 3 radicals are generated. When the substrate temperate is above 200 °C, hydrogen effusion decreases Si H bonding and optical band gap of 1.74 eV is obtained. The properties of i-type a-Si:H depending on plasma conditions show hydrogen content (C(H)) = 6–11%, R * = 0–0.2 and E g = 1.74–1.86 eV. The properties of region of low structural defect and good passivation represent C(H) = about 10 at.%, R * = 0 and E g = 1.77 eV. |
| Databáze: | OpenAIRE |
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