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Title: Detection of miniband formation in strain-balanced InGaAs/GaAsP quantum well solar cells by using a piezoelectric photothermal spectroscopy

To investigate the effect of the miniband formation on the optical absorption spectrum, we adopted two non-destructive methodologies of piezoelectric photothermal (PPT) and photoreflectance (PR) spectroscopies for strain-balanced InGaAs/GaAsP multiple quantum-well (MQW) and superlattice (SL) structures inserted GaAs p-i-n solar cells. Because the barrier widths of the SL sample were very thin, miniband formations caused by coupling the wave functions between adjacent wells were expected. From PR measurements, a critical energy corresponding to the inter-subband transition between first-order electron and hole subbands was estimated for MQW sample, whereas two critical energies corresponding to the mini-Brillouin-zone center (Γ) and edge (π) were obtained for SL sample. The miniband width was calculated to be 19 meV on the basis of the energy difference between Γ and π. This coincided with the value of 16 meV calculated using the simple Kronig–Penney potential models. The obtained PPT spectrum for the SL sample was decomposed into the excitonic absorption and inter-miniband transition components. The latter component was expressed using the arcsine-like signal rise corresponding to the Γ point in the mini-Brillouin zone that was enhanced by the Sommerfeld factor. The usefulness of the PPT methodology for investigating the inserted MQW and/or SL structure inserted solar cells ismore » clearly demonstrated.« less
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Faculty of Engineering, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 889-2192 (Japan)
  2. Interdisciplinary Research Organization, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 889-2192 (Japan)
  3. School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan)
  4. Research Center for Advanced Science and Technology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan)
Publication Date:
OSTI Identifier:
22308566
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ABSORPTION SPECTRA; BALANCES; BRILLOUIN ZONES; COUPLING; DETECTION; GALLIUM ARSENIDES; INDIUM COMPOUNDS; PHOSPHORUS COMPOUNDS; PIEZOELECTRICITY; QUANTUM WELLS; SOLAR CELLS; SPECTROSCOPY; STRAINS; SUPERLATTICES; WAVE FUNCTIONS