Two-step photocarrier generation in InAs/GaAs quantum dot superlattice intermediate band solar cell

Author

Tomoyuki Kada;Taizo Tanibuchi;Shigeo Asahi;Toshiyuki Kaizu;Yukihiro Harada;Takashi Kita;Ryo Tamaki;Yoshitaka Okada;Kenjiro Miyano

Author_Institution

Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, 657-8501, JAPAN

fYear

2015

fDate

6/1/2015 12:00:00 AM

Firstpage

1

Lastpage

4

Abstract

We studied the two-step photon absorption (TSPA) process in InAs/GaAs quantum-dot superlattice (QDSL) solar cells. The photoluminescence (PL) and its excitation spectrum (PLE) showed the contribution of the higher excited states (ESs) forming the miniband of the QDSLs above the inhomogeneously distributed ground states (GSs). TSPA of sub- bandgap photons efficiently occurs when electrons are pumped from the valence band (VB) to the higher ESs. When the higher ESs were resonantly excited, the superlinear excitation power dependence of the PL intensity appeared. Moreover, time-resolved PL showed that the electron lifetime is extended. These results demonstrate that the excited electron and hole separately relax into QDSLs, and thereby, enhancing the second sub-bandgap absorption.

Keywords

"Absorption","Gallium arsenide","Photovoltaic cells","Wavelength measurement","Yttrium","Electron optics","Optical device fabrication"

Publisher

ieee

Conference_Titel

Photovoltaic Specialist Conference (PVSC), 2015 IEEE 42nd

Type

conf

DOI

10.1109/PVSC.2015.7355810

Filename

7355810