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Title: Effect of space layer doping on photoelectric conversion efficiency of InAs/GaAs quantum dot solar cells

We report an effect of photoelectric conversion efficiency (PCE) by space layer doping in InAs/GaAs quantum dot solar cells (QDSC) and δ-doped QDSC grown by molecular beam epitaxy. The PCEs of QDSC and δ-doped QDSC without anti-reflection coating were 10.8% and 4.3%, respectively. The QDSC had about four electrons per QD, and its ideality factor was temperature-independent, which implies that recombination of electron-hole pairs is suppressed by strong potential barriers around charged dots. From the deep level transient spectroscopy measurements, four defect levels, including QD with the activation energy ranges from 0.08 eV to 0.50 eV below GaAs conduction band edge, appeared. Especially, the M1 defect (E{sub c}-0.14 eV) was newly formed in δ-doped QDSC and its density was higher than those of M3 (E{sub c}-0.35 eV) and M4 (E{sub c}-0.50 eV) levels in QDSC. These results suggest that the photo-carriers recombining at M1 defect might be responsible for the reduction of PCE in δ-doped QDSC.
Authors:
; ;  [1] ;  [2]
  1. Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of)
  2. Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22486103
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 20; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACTIVATION ENERGY; CARRIERS; CONVERSION; DEEP LEVEL TRANSIENT SPECTROSCOPY; DOPED MATERIALS; EFFICIENCY; EV RANGE; GALLIUM ARSENIDES; HOLES; INDIUM ARSENIDES; LAYERS; MOLECULAR BEAM EPITAXY; POTENTIALS; QUANTUM DOTS; SOLAR CELLS