Investigation of co-doped GaAs:NSb/AlGaAs IBSC with ideal transition energies for high efficiency Solar Cells

2016 Fiscal Year Final Research Report

• Project/Area Number: 26790007
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Nanostructural physics
• Research Institution: National Institute for Materials Science
• Principal Investigator: Elborg Martin 国立研究開発法人物質・材料研究機構, 若手国際研究センター, ICYS研究員 (60724630)
• Research Collaborator: Noda Takeshi ; Mano Takaaki ; Sakuma Yoshiki ; Bollmann Joachim ; Venter Andre ; Venter Danielle
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 太陽電池 / 量子構造 / MBE, エピタキシャル / GaNAs / 中間バンド太陽電池 / 2段階光子吸収 / 開路電圧

Outline of Final Research Achievements

We study dilute-N GaAs quantum wells (QWs) for application in Intermediate Band Solar Cells (IBSCs) with proposed conversion efficiencies exceeding the Schokley-Queisser limit of single-junction solar cells. We investigate the optical properties of GaNAs QWs exhibiting both confined quantum states as well as optically active N-induced defect states. The energy levels are characterized by capacitance spectroscopic techniques (DLTS, Admittance, CV measurement). We optimize the epitaxial growth to achieve close-to-ideal transition energies in GaNAs/AlGaAs QWs. Co-doping with Sb leads to improved optical quality. Using a strain-free GaAs/AlGaAs quantum dot model system, we demonstrate clear two-step photocurrent generation at room temperature, the key IBSC operating principle. We realize a recovery of open-circuit voltage in GaNAs/AlGaAs QW embedded solar cells for deeply confined structures. Our results represent a major advancement in the pursuit to realize the IBSC concept.

Free Research Field

物質科学