Se Diffusion in CdTe Thin Films for Photovoltaics

Eric Colegrove, Xin Zheng, Tursun Ablekim, Joel Duenow, Craig Perkins, Helio Moutinho, Wyatt Metzger

Research output: Contribution to journalArticlepeer-review

11 Scopus Citations

Abstract

Manipulating CdSeTe bandgrading to enhance photocurrent and carrier lifetime is an essential part of high-performance CdTe photovoltaics (PVs). In this work, we examine Se diffusion kinetics in single-crystal and polycrystalline CdTe during deposition, thermal annealing, and CdCl2 treatments. Se distributions are determined by dynamic secondary-ion-mass spectroscopy and Auger electron spectroscopy depth profiling and coupled with electron backscatter diffraction images of the crystalline structure. Effective bulk and grain boundary diffusion coefficients are determined by analytical models and discussed in the context of processing and film morphology. Se is found to diffuse in CdTe at much higher rates during CdCl2 treatments than with thermal processing alone. GB diffusion also occurs at a significantly faster rate than bulk diffusion. As a result of these two effects, the near interface bulk and GB Se diffusion during CdCl2 treatments dominates the bandgrading profiles in CdTe PVs.

Original languageAmerican English
Article number025501
Number of pages9
JournalJournal of Physics D: Applied Physics
Volume54
Issue number2
DOIs
StatePublished - Jan 2021

Bibliographical note

Publisher Copyright:
© 2020 IOP Publishing Ltd.

NREL Publication Number

  • NREL/JA-5K00-77039

Keywords

  • CdSeTe
  • CdTe
  • Diffusion
  • grain boundary
  • photovoltaics
  • polycrystalline
  • Se

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