Enhanced p-Type Dopability of P and As in CdTe using Non-Equilibrium Thermal Processing

Jihui Yang, Wan-Jian Yin, Wyatt Metzger, Timothy Gessert, Teresa Barnes, Suhuai Wei, Ji-Sang Park, James Burst

Research output: Contribution to journalArticlepeer-review

65 Scopus Citations

Abstract

One of the main limiting factors in CdTe solar cells is its low p-type dopability and, consequently, low open-circuit voltage (VOC). We have systematically studied P and As doping in CdTe with first-principles calculations in order to understand how to increase the hole density. We find that both P and As p-type doping are self-compensated by the formation of AX centers. More importantly, we find that although high-temperature growth is beneficial to obtain high hole density, rapid cooling is necessary to sustain the hole density and to lower the Fermi level close to the valence band maximum (VBM) at room temperature. Thermodynamic simulations suggest that by cooling CdTe from a high growth temperature to room temperature under Te-poor conditions and choosing an optimal dopant concentration of about 1018/cm3, P and As doping can reach a hole density above 1017/cm3 at room temperature and lower the Fermi level to within ∼0.1eV above the VBM. These results suggest a promising pathway to improve the VOC and efficiency of CdTe solar cells.

Original languageAmerican English
Article number025102
Number of pages6
JournalJournal of Applied Physics
Volume118
Issue number2
DOIs
StatePublished - 14 Jul 2015

Bibliographical note

Publisher Copyright:
© 2015 AIP Publishing LLC.

NREL Publication Number

  • NREL/JA-5K00-64932

Keywords

  • doping
  • Fermi levels
  • hole density
  • hole doped superconductors
  • II-VI semiconductors

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