Phosphorus Diffusion Mechanisms and Deep Incorporation in Polycrystalline and Single-Crystalline CdTe

Eric Colegrove, Steven Harvey, Jihui Yang, David Albin, Suhuai Wei, Wyatt Metzger, James Burst

Research output: Contribution to journalArticlepeer-review

25 Scopus Citations

Abstract

A key challenge in cadmium-telluride (CdTe) semiconductors is obtaining stable and high hole density. Group-I elements substituting Cd can form acceptors but easily self-compensate and diffuse quickly. For example, CdTe photovoltaics have relied on copper as a dopant, but this creates stability problems and hole density that has not exceeded 1015 cm-3. If hole density can be increased beyond 1016 cm-3, CdTe solar technology can exceed multicrystalline silicon performance and provide levelized costs of electricity below conventional energy sources. Group-V elements substituting Te offer a solution, but they are very difficult to incorporate. Using time-of-flight secondary-ion mass spectrometry, we examine bulk and grain-boundary diffusion of phosphorus (P) in CdTe in Cd-rich conditions. We find that in addition to slow bulk diffusion and fast grain-boundary diffusion, there is a critical fast bulk-diffusion component that enables deep P incorporation in CdTe. Detailed first-principle calculations indicate the slow bulk-diffusion component is caused by substitutional P diffusion through the Te sublattice, whereas the fast bulk-diffusion component is caused by P diffusing through interstitial lattice sites following the combination of a kick-out step and two rotation steps. The latter is limited in magnitude by high formation energy, but is sufficient to manipulate P incorporation. In addition to an increased physical understanding, these results open up experimental possibilities for group-V doping in CdTe applications.

Original languageAmerican English
Article number054014
Number of pages7
JournalPhysical Review Applied
Volume5
Issue number5
DOIs
StatePublished - 19 May 2016

Bibliographical note

Publisher Copyright:
© 2016 American Physical Society.

NREL Publication Number

  • NREL/JA-5K00-65666

Keywords

  • CdTe
  • diffusion
  • grain boundary
  • group V
  • polycrystalline
  • single crystal

Fingerprint

Dive into the research topics of 'Phosphorus Diffusion Mechanisms and Deep Incorporation in Polycrystalline and Single-Crystalline CdTe'. Together they form a unique fingerprint.

Cite this