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Title: Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation

Laser processing of polycrystalline CdTe is a promising approach that could potentially increase module manufacturing throughput while reducing capital expenditure costs. For these benefits to be realized, the basic effects of laser irradiation on CdTe must be ascertained. In this study, we utilize surface photovoltage spectroscopy (SPS) to investigate the changes to the electronic properties of the surface of polycrystalline CdTe solar cell stacks induced by continuous-wave laser annealing. The experimental data explained within a model consisting of two space charge regions, one at the CdTe/air interface and one at the CdTe/CdS junction, are used to interpret our SPS results. The frequency dependence and phase spectra of the SPS signal are also discussed. To support the SPS findings, low-temperature spectrally-resolved photoluminescence and time-resolved photoluminescence were also measured. The data show that a modest laser treatment of 250 W/cm{sup 2} with a dwell time of 20 s is sufficient to reduce the effects of Fermi level pinning at the surface due to surface defects.
Authors:
 [1] ;  [1] ;  [2] ; ;  [3] ;  [1] ;  [4]
  1. Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)
  2. (India)
  3. Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
22412932
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 22; Other Information: (c) 2015 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; ANNEALING; CADMIUM SULFIDES; CADMIUM TELLURIDES; EMISSION SPECTROSCOPY; FERMI LEVEL; FREQUENCY DEPENDENCE; INTERFACES; LASER RADIATION; PHOTOLUMINESCENCE; POLYCRYSTALS; RECOMBINATION; SEMICONDUCTOR JUNCTIONS; SOLAR CELLS; SURFACES