2005 Fiscal Year Final Research Report Summary
Electrodeposition of ZnTe Photovoltaic Semiconductor for Electrode Materials
| Project/Area Number |
15360399
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Metal making engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
ICHINO Ryoichi Nagoya Univ., Graduate School of Eng., Assoc. Prof., 大学院・工学研究科, 助教授 (70223104)
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| Co-Investigator(Kenkyū-buntansha) |
OKIDO Masazumi Nagoya Univ., Graduate School of Eng., Prof., 大学院・工学研究科, 教授 (50126843)
KURODA Kensuke Nagoya Univ., Graduate School of Eng., Assist. Prof., 大学院・工学研究科, 助手 (00283408)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Compound Semi-conductor / Electrodeposition / Photovoltaic Semiconductor / ZnTe / Organic Solvent / Electrolysis in Molten Salts / Cu Doping / UPD |
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| Research Abstract |
Zinctelluride, ZnTe is expected as semiconductors useful for photovoltaic device. We have investigated the electrodeposition of the compound films from ionic liquids such as organic solvents and molten salts. The potential window for the organic solvents increases with increasing boiling point. The film in single phase consisting of ZnTe could be obtained by controlling the bath composition, temperature and applied potential. The optimal conditions to obtain ZnTe film with smooth and compact crystal were compared in sulfuric acid solution at 343 K, propylene carbonate bath at 423 K and molten chloride at 673 K and 640 K, containing Zn and Te ions.
In particular, ZnTe with high crystallinity could be obtained in propylene carbonate by the under-potential deposition (UPD) of Zn, and the current efficiency was enhanced considerably. A single-phase ZnTe film close to the ideal stoichiometric composition of ZnTe could be obtained at 423 K and -0.8V vs.Ag/AgCl in propylene carbonate with a molar ratio of Zn^<2+>/Te^<4+>=10 and a low Te^<4+> concentration ; the film had a smooth and dense granular, crystal morphology.
As for the electrolysis in LiCl- KCl- ZnCl_2- TeCl_4 molten salts, ZnTe films were obtained on the W substrate by UPD mechanism of Zn. A single phase ZnTe with compact and smooth morphology was electrodeposited at 0 V in LiCl- KCl- 0.02mol%ZnCl_2- 0.01mol%TeCl_4 at 673 K.
On the other hand, ZnTe films were obtained on zinc substrates as a single phase at 640 K by using the ion exchange and chemical reaction and alloying. The Te^<4+> species was supplied to the substrate as a vapor from the eutectic LiCl-KCl molten salts containing TeCl_4 (0.05-0.9 mol%). The phase of the obtained film depended on the reaction time and the TeCl_4 content.
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