Effects of thermal cycle annealing on reduction of defect density in lattice-mismatched InGaAs solar cells

T. Sasaki, K. Arafune, H. S. Lee, N. J. Ekins-Daukes, S. Tanaka, Y. Ohshita, M. Yamaguchi

Research output: Contribution to journalConference articlepeer-review

20 Citations (Scopus)


Lattice-mismatched In0.16Ga0.84As solar cells were grown on GaAs substrates using graded InxGa1- xAs buffer layers and homogenous In0.16Ga 0.84As buffer layers. The indium composition x in the graded buffer changed from 0% to 16% continuously. Thermal cycle annealing (TCA) was performed after the growth of the graded buffer layers. The effects of TCA on the solar cell open-circuit voltage and quantum efficiency have been investigated. The minority carrier lifetime is observed to increase in the p-type In0.16Ga0.84As layer after applying the TCA process. Electron-beam-induced current microscopy also shows a related reduction in dislocation density in the p-type In0.16Ga 0.84As layer after TCA processing. Cross-sectional transmission electron microscopy performed on the graded buffer layer suggests that the strain present in the cell layers is reduced after the TCA process, implying that the TCA treatment promotes strain relaxation in the graded buffer layers.

Original languageEnglish
Pages (from-to)626-629
Number of pages4
JournalPhysica B: Condensed Matter
Issue number1
Publication statusPublished - 2006 Apr 1
Externally publishedYes
EventProceedings of the 23rd International Conference on Defects in Semiconductors -
Duration: 2005 Jul 242005 Jul 29

Bibliographical note

Funding Information:
The authors would like to thank Dr. T. Takamoto and Dr. T. Agui. This work is partially supported by the Ministry of Education, Culture, Sports, Science and Technology as a Private University Academic Frontier Research Center Program “Super High-Efficiency Photovoltaic Research Center” 2002–2006.


  • Graded buffer
  • InGaAs
  • Solar cells
  • Thermal cycle annealing

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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