S-Te Interdiffusion within Grains and Grain Boundaries in CdTe Solar Cells

Mowafak Al-Jassim, C. Li, J. Poplawsky, N. Paudel, T. Pennycook, S. Haigh, Y. Yan, S. Pennycook

Research output: Contribution to journalArticlepeer-review

26 Scopus Citations

Abstract

At the CdTe/CdS interface, a significant Te-S interdiffusion has been found a few nanometers into the CdTe grain interiors with scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy. This interdiffusion happens on both as-grown and CdCl2-treated CdTe. S substitution at Te sites has been directly resolved in CdTe with STEM Z-contrast images, which further confirms the S diffusion into CdTe grain interiors. Moreover, when a sufficient amount of S substitutes for Te, a structural transformation from zinc-blende to wurtzite has been observed. In the CdCl2-treated CdTe, Cl segregation has also been found at the interface. STEM electron-beam-induced current shows that the p-n junction occurs a few namometers into the CdTe grains, which is consistent with the S diffusion range we observe. The shift of the p-n junction suggests a buried homojunction which would help reduce nonradiative recombination at the junction. Meanwhile, long-range Sdiffusion in CdTe grain boundaries (GBs) has been detected, as hasTe and Cl diffusion in CdS GBs.

Original languageAmerican English
Article number6905708
Pages (from-to)1636-1643
Number of pages8
JournalIEEE Journal of Photovoltaics
Volume4
Issue number6
DOIs
StatePublished - Nov 2014

Bibliographical note

Publisher Copyright:
© 2014 IEEE.

NREL Publication Number

  • NREL/JA-5K00-63314

Keywords

  • CdTe
  • interface scanning transmission electron microscopy
  • thin-film photovoltaic

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