1998 Fiscal Year Final Research Report Summary
Development of ultra-uniform low-resistivity ZnO thin film by the atomic layer deposition
| Project/Area Number |
09650347
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
YAMADA Akira Tokyo Institute of Technology Faculty of Engineering, Associate Professor, 工学部, 助教授 (40220363)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Tamotsu Tokyo Inst.of Tech.Res.Center for Quantum Effect Elect., Research Associate, 量子効果エレクトロニクス研究センター, 助手 (80233378)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Atomic Layer Deposition / ZnO / Solar Cell / TCO |
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| Research Abstract |
In this study, high-quality ZnO TCO films were successfully grown by atomic layer deposition (ALD) using diethylzinc (DEZn) and H_2O as reactant gases. Self-limiting growth was observed, for the first time, for substrate temperatures ranging from 105 to 165。C.The films had a very good uniformity over large area substrate due to the self-limiting feature of ALD, indicating the capability of ALD technique to be used for large-scale production of ZnO films.
Furthermore, boron doping has successufully been carried out using B_2H_6 as a dopant gas in the ALD of ZnO.The electrical properties of ZnO films were improved by boron doping and a low sheet resistivity of 12OMEGA was obtained for B-doped ZnO film which was only 400nm thick. The ZnO films grown by ALD exhibited excellent stability in the electrical properties under the vacuum annealing at various temperatures and under air exposure at room temperature, indicating high reliability of the ZnO films.
In order to obtain textured and low-resistivity ZnO films, a two-step process was proposed, which was carried out by combining the ALD and MOCVD techniques. The first layer was grown by the MOCVD method in order to obtain the tetrapod-like morphology, which was then followed by the second layer deposition using the ALD technique. The electrical and optical properties of ZnO films were effectively improved by depositing the lower resistivity ALD-ZnO films on to the textured MOCVD-ZnO films while the textured surface morphologies were well maintained.
Finally, the obtained high-quality ZnO films by the two-step process were successfully applied to p-i-n a-Si solar cells as front contacts. Upon optimizing the electrical properties and surface morphologies of ZnO films, a very high stabilized conversion efficiency of 8.2% was obtained for the cell of 1cm2 with a structure of glass/ZnO/p/buffer/i/n/ZnO/Ag/Al under AM-1.5 illumination.
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Research Products
(8 results)
