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成果報告書詳細
管理番号20170000000094
タイトル*平成27年度中間年報 高性能・高信頼性太陽光発電の発電コスト低減技術開発 太陽電池セル、モジュールの共通基盤技術開発 先端複合技術シリコン太陽電池プロセス共通基盤に関する研究開発(新規へテロ接合用材料に関する研究)
公開日2017/6/2
報告書年度2015 - 2015
委託先名国立大学法人名古屋大学
プロジェクト番号P15003
部署名新エネルギー部
和文要約
英文要約Title: Development of high performance and reliable PV modules to reduce levelized cost of energy, Development of common components for solar cells and modules,Investigation of innovative materials to fabricate high quality heterojunction structures on crystalline Si surface Research duration:(FY2015-FY2017)FY2015 Annual Report by Nagoya University

We attempted to develop new materials to fabricate heterojunction structure on crystalline Si (c-Si) surface, which contains high-quality passivation layers and carrier selective contact layers. As for the passivation layers, chemically and thermally grown SiO2 layers were utilized on n-type c-Si surface. Before the oxidation, the c-Si substrates were cleaned by RCA cleaning and etched with 5% HF followed by oxidation with HNO3 at 80 °C for 10min. Then the chemically oxidized substrates were annealed for further thermal oxidation. As a result, presence of the chemical oxide was found to be effective for higher lifetime of the substrate. The developed oxide layer will be utilized as passivation layer between c-Si and a selective contact layer.
To improve solar cell performance, we develop new materials for carrier selective contact layer, which can transport either type of carrier and block another type of carrier. We focus on p-type polycrystalline Si (poly-Si) grown by Aluminum induced crystallization (AIC) for hole selective contact layer because it contains Al dopants up to solubility limit with large crystal grains. At first, we tried to apply the AIC poly-Si on SiO2 to back side of p-type c-Si instead of Al BSF. As a result, similar solar cell properties were obtained in the sample with AIC poly-Si after optimization of the poly-Si thickness compared to the conventional structure with Al BSF. Higher performance of solar cells is expected by optimization of AIC growth parameters.
In recent years, regeneration process, which include deactivation of BO defects in a p-type Si substrate by light illumination and annealing less than 200 °C, has attracted much attention. Interestingly, we found that carrier lifetime can be enhanced by only light illumination in boron-doped CZ Si without annealing. For the sample preparation, Al2O3 layers were deposited by thermal atomic layer deposition followed by SiNx:H deposition by plasma enhanced chemical vapor deposition on the both surfaces of Si substrates. Then the sample was fired at 550 °C to diffuse H atoms from SiNx:H layer into the Si substrate. Lifetime measurements were carried out by quasi-steady state photo-conductance. As a result, lifetime in the sample with the firing increased from 180usec to 550usec by light illumination. Although underlying mechanism has not been clarified yet, this phenomenon could work as key process for high performance solar cells.
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