Using Time-of-Flight SIMS to Investigate Group V Dopant Distribution in CdTe

Steven Harvey, Eric Colegrove, David Albin, Mowafak Al-Jassim, Wyatt Metzger, Brian McCandless

Research output: Contribution to conferencePaper

1 Scopus Citations

Abstract

Enabling continued development of polycrystalline CdTe solar cells with open-circuit voltages approaching 1 V requires new dopants and processes to increase acceptor concentrations and minority-carrier lifetimes. We have investigated multiple Group V dopants in single- and polycrystalline CdTe materials as well as Cl, using numerous dopant incorporation and activation strategies. The diffusion kinetics and spatial distribution of the dopants are revealed with a combination of 1-D standard depth-profiling and high-resolution 3-D tomography with time-of-flight secondary-ion mass spectrometry. For all cases where the dopant is incorporated during growth, including vapor-transport deposition, closespaced sublimation, and molecular-beam epitaxy, the dopant concentration is not enhanced at grain boundaries. When the dopant is incorporated through a post-growth incorporation process, fast grain-boundary diffusion leads to an enhanced dopant concentration at grain boundaries. Although both methods are applicable, in-situ incorporation offers control of dopants and devices independent of diffusion kinetics, grain structure, and grain-boundary chemistry.
Original languageAmerican English
Pages3319-3322
Number of pages4
DOIs
StatePublished - 2018
Event2017 IEEE 44th Photovoltaic Specialist Conference (PVSC) - Washington, D.C.
Duration: 25 Jun 201730 Jun 2017

Conference

Conference2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)
CityWashington, D.C.
Period25/06/1730/06/17

NREL Publication Number

  • NREL/CP-5K00-67795

Keywords

  • CdTe
  • diffusion
  • doping
  • Group V
  • TOF-SIMS

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