Two-step photocurrent generation enhanced by the fundamental-state miniband formation in intermediate-band solar cells using a highly homogeneous InAs/GaAs quantum-dot superlattice

• Published in: Applied physics express Vol. 11; no. 1; pp. 12301 - 12304
• Main Authors: Hirao, Kazuki, Asahi, Shigeo, Kaizu, Toshiyuki, Kita, Takashi
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 01.01.2018
• ISSN: 1882-0778; 1882-0786
• DOI: 10.7567/APEX.11.012301

We studied intermediate-band solar cells (IBSCs) incorporating highly homogeneous InAs/GaAs quantum dot superlattices (QDSLs). The extra photocurrent generated by two-step photon absorption markedly increases at the fundamental state (FS) because the FS miniband has been successfully formed in the QDSL-IBSC by controlling the QD size homogeneity. Here, the carriers excited into the miniband spatially separate in the internal electric field, and the long-lived electrons in the intermediate states of the miniband increase the inter-subband absorption strength. The two-step photocurrent response, therefore, extends toward the longer-wavelength side corresponding to the QDSL-FS at approximately 1.2 µm.