Reduction of defect density in silicon quantum dot light-absorbers using hydrogen plasma treatment

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05075
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: Nagoya University
• Principal Investigator: Kurokawa Yasuyoshi 名古屋大学, 工学研究科, 准教授 (00588527)
• Co-Investigator(Kenkyū-buntansha): 加藤 慎也 名古屋工業大学, 工学(系)研究科(研究院), 助教 (10775844)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: シリコン / 量子ドット / プラズマ / 太陽電池 / ベイズ最適化

Outline of Final Research Achievements

The bandgap of silicon quantum dots (Si-QDs) can be tuned by the quantum size effect and it is possible to fabricate solar cells with active layers tuned to ambient light. To reduce the defect density in Si-QD active films is one of issues. In this study, hydrogen plasma treatment (HPT) was conducted to decrease the defect density in Si-QD active layers. Since HPT has 6 process parameters, a Bayesian optimization approach was adopted to find the optimal conditions. Photosensitivity (PS) was adopted as the objective function for BO. The PS is obtained by dark and photo conductivities of Si-QD active layers. As a result, the PS was improved from 22.7 to 347.2 with 7 cycles BO processes. Under the optimal conditions, Si-QD solar cells were fabricated. The open-circuit voltage and fill factor of 689 mV and 0.67 were obtained, respectively. These values are the highest among conventional Si-QD solar cells. Such significant improvements were achieved with the combination of BO and HPT.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

今回の研究にて、シリコン量子ドット太陽電池の開放電圧と曲線因子はそれぞれ689mVと0.67に達した。これらの特性値は同様のデバイスの中でも最高値であり、BOとHPTを組み合わせたことで吸収層の大幅な性能向上を達成できた結果と考えられる。本研究成果はプラズマプロセスへのベイズ最適化の有用性を示すとともにシリコン量子ドット太陽電池のポテンシャルも示した点で学術的には意義がある。シリコン量子ドットを用いた太陽電池は環境光にチューニングが容易にできることから、IoT用電源として用いることができ、IoTセンサネットワーク構築のための電源としても有望である。