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成果報告書詳細
管理番号20170000000088
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 先端複合技術型シリコン太陽電池、高性能CIS太陽電池の技術開発 基盤技術開発による先端複合技術セルのための低再結合電極の研究開発
公開日2017/6/2
報告書年度2015 - 2015
委託先名ナミックス株式会社
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, technological development of advanced composite silicon solar cells and high-performance CIS solar cells (FY 2015-2017) FY 2015 Annual Report

In this research, the most important objective is that the carrier transport pass formation without SiNx etching. To achieve this, we looked for the new amorphous complex oxide. The lead-borosilicate system was out of the searching list, because of lead-borosilicate system removing SiNx. The new amorphous complex oxides were synthesized by melt-quenching method. The mixed raw oxides powder were put into the furnace with crucible and keep a specific time. Then, melted oxide was quenched by metallic roller. The synthesized sample was ground for paste formulation. According to the survey of synthesized sample, the good candidate oxide system was found.

Normally, metal-Si contact is Schottky contact. To make low contact resistance, Ohmic contact, high concentration doping layer is formed on Si surface. The diffusion process affect to the surface condition and concentration profile. The contact resistance might control both of them. Therefore, in this research, Si wafer without diffusion process was used for the Test Element Group (TEG). The n-Si substrate was chosen for TEG preparation. The specific resistance was about 50 mΩ cm. The wafer was cleaned by HF and then normal PECVD was applied for SiNx layer formation. The dot pattern was printed on the SiNx surface. The Al/Ag paste was printed on rear side (no PECVD surface) for the Ohmic contact formation. The both side printed precursor was fired under the same condition as cell fabrication condition. The conventional paste and novel one were used. The j-V characteristics was measured using this TEG. The conventional paste showed higher reverse current. On the other hand, the reverse current was suppressed in case of the novel paste. Generally, metal-Si contact is Schottky contact and reverse current is not occur. However, the interface state become the one of cause of such “leak current”, as well known. Therefore, the formation of interface state might be the big issue for metallization (open circuit voltage loss). The further TEG evaluation, such as temperature dependence, might be reveal the carrier transport mechanism.

The interface structural analysis is quite important for reveal the carrier transport mechanism. The Feld Emission Scanning Electron Microscope observation relatively thick interfacial layer was observed between metal and Si. This layer was analyzed by Feld Emission Auger Electron Spectroscopy, and Si, O, N and Ag were detected. This result indicates the SiNx layer was transformed to SiNxOy by the novel paste and during transformation, Ag was diffusing into this layer. Such interface layer might suppress the interfacial state formation and main carrier transport pass. For the further research, carrier transport mechanism must be analyzed by TEG test.
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