Design of Epitaxial CdTe Solar Cells on InSb Substrates

Ana Kanevce, Tao Song, James Sites

Research output: Contribution to journalArticlepeer-review

13 Scopus Citations

Abstract

Epitaxial CdTe has been shown by others to have a radiative recombination rate approaching unity, high carrier concentration, and low defect density. It has, therefore, become an attractive candidate for high-efficiency solar cells, perhaps becoming competitive with GaAs. The choice of substrate is a key design feature for epitaxial CdTe solar cells, and several possibilities (CdTe, Si, GaAs, and InSb) have been investigated by others. All have challenges, and these have generally been addressed through the addition of intermediate layers between the substrate and CdTe absorber. InSb is an attractive substrate choice for CdTe devices, because it has a close lattice match with CdTe, it has low resistivity, and it is easy to contact. However, the valence-band alignment between InSb and p-type CdTe, which can both impede hole current and enhance forward electron current, is not favorable. Three strategies to address the band-offset problem are investigated by numerical simulation: heavy doping of the back part of the CdTe layer, incorporation of an intermediate CdMgTe or CdZnTe layer, and the formation of an InSb tunnel junction. Each of these strategies is predicted to be helpful for higher cell performance, but a combination of the first two should be most effective.

Original languageAmerican English
Article number7234833
Pages (from-to)1762-1768
Number of pages7
JournalIEEE Journal of Photovoltaics
Volume5
Issue number6
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 IEEE.

NREL Publication Number

  • NREL/JA-5J00-64499

Keywords

  • CdTe
  • epitaxial
  • InSb
  • single-crystal
  • solar cells
  • substrates

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