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- Title
Electrical and optical characterizations of InAs/GaAs quantum dot solar cells.
- Authors
Han, Im Sik; Kim, Seung Hyun; Kim, Jong Su; Noh, Sam Kyu; Lee, Sang Jun; Kim, Honggyun; Kim, Deok-Kee; Leem, Jae-Young
- Abstract
The electrical and optical characterizations of InAs/GaAs quantum dot solar cells (QDSCs) were investigated by frequency dependent capacitance-voltage (<italic>C</italic>-<italic>V</italic>) measurements and photoreflectance (PR) spectroscopy. The <italic>C</italic>-<italic>V</italic> results confirmed that the frequency dependent junction capacitance (<italic>C</italic>j) of QDSC is sensitive to the carrier exhaustion process through trapping and recapturing in the strain-induced defects and QD states caused by the interface strain between InAs and GaAs materials. As a result, at a low frequency (≤ 200 kHz), the <italic>C</italic>j of the QDSCs decreased with increasing InAs deposition thickness (<italic>θ</italic>), leading to the decrease in carrier concentration (<italic>N</italic>d) of the n-GaAs absorber layer due to the carrier losses processes caused by the trapping and re-capturing in the defects and the relatively large QDs. At <italic>θ</italic> ≤ 2.0 ML, the p-n junction electric field strength (<italic>F</italic>pn) of the QDSCs which was evaluated by PR spectra decreased with increasing excitation photon intensity (<italic>I</italic>ex) due to the typical field screening effect in the SC structure. On the other hand, the <italic>F</italic>pn of QDSCs with <italic>θ</italic> ≥ 2.5 ML approached a constant value with a relatively high <italic>I</italic>ex, which suggests that the decrease in photo-generated carriers in the QDSC was caused by the re-capturing and trapping process.
- Subjects
QUANTUM dots; SOLAR cells; PHOTOREFLECTANCE; INDIUM arsenide; GALLIUM arsenide
- Publication
Applied Physics A: Materials Science & Processing, 2018, Vol 124, Issue 3, p1
- ISSN
0947-8396
- Publication type
Article
- DOI
10.1007/s00339-018-1661-y