Development of the Infrared Laser Lift-Off Process for Low-Cost GaAs Based Solar Cells

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H04979
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Energy engineering
• Research Institution: The University of Tokyo
• Principal Investigator: Watanabe Kentaroh 東京大学, 先端科学技術研究センター, 特任講師 (30523815)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 化合物半導体 / 太陽電池 / GaAs / 多重量子井戸 / エピタキシャルリフトオフ / レーザーリフトオフ / IR-LLO

Outline of Final Research Achievements

In order to reduce the cost of III-V compound semiconductor solar cells, which can realize a very high efficiency, the basic study for an infrared laser lift off (IR-LLO) process has been carried out. The strain-balance multiple quantum wells (MQWs) consist of InGaAs well and InGaP barrier can selectively absorb infrared photon corresponding to 1.25 eV of effective bandgap energy. By applying the MQWs as a release layer, an epitaxially grown GaAs photovoltaic (PV) device via MQWs on the GaAs substrate was transferred to the support substrate. The illumination test of pulse laser (1064 nm) on the MQWs layer grown on GaAs indicated the selective ablation of MQW is possible with controlled laser power density. Finally, the PV layer separation and transfer was demonstrated by the IR-LLO method was demonstrated for mm size of small samples.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

本研究によって、GaAsからなる太陽電池がレーザー光を用いたドライプロセスによって剥離加工が可能であることが示された。この結果は宇宙用として用いられる化合物半導体からなる超高効率太陽電池のコスト低減と生産性の向上に寄与することができる。そのため、今後はSi結晶による太陽電池に代わり、地上応用へ向けて高効率多接合太陽電池市場の拡大に資することが期待される。