Charge Transport Mechanisms in a Pb2P2Se6 Semiconductor

Svetlana S. Kostina, Micah P. Hanson, Peng L. Wang, John A. Peters, David A. Valverde-Chávez, Pice Chen, David G. Cooke, Mercouri G Kanatzidis, Bruce W. Wessels

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Abstract

Charge transport in semi-insulating Pb2P2Se6 single crystals was investigated. The dark current was dominated by the ionization of deep-level defects within the gap of the material, with activation energies between 0.6 and 0.8 eV. A model for charge transport was developed where a continuum of these midgap defect levels determined the conductivity of Pb2P2Se6. Current-voltage characteristics in Pb2P2Se6 single crystals showed nonlinear behavior at high voltages. The nonlinear characteristics are attributed to competing Poole-Frenkel emission and phonon-assisted tunneling processes, such that at lower fields the former effect dominates, while at higher electric fields the latter mechanism emerges. Calculated tunneling times in the 250-500 fs range indicate that the deep traps promote weak electron-phonon coupling and that the tunneling involves deep defect levels. Transient multi-terahertz spectroscopy and temperature-dependent photoconductivity measurements reveal signatures of dispersive transport and low mobility on the order of 10 cm2/(V s), consistent with a disordered potential energy landscape in Pb2P2Se6. Photoresponse in these crystals is therefore limited by a distribution of trapping and recombination sites within the band gap.

Original languageEnglish
Pages (from-to)1877-1887
Number of pages11
JournalACS Photonics
Volume3
Issue number10
DOIs
Publication statusPublished - Oct 19 2016

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Keywords

  • charge transport
  • conductivity
  • deep levels
  • terahertz spectroscopy
  • transient spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biotechnology
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

Cite this

Kostina, S. S., Hanson, M. P., Wang, P. L., Peters, J. A., Valverde-Chávez, D. A., Chen, P., Cooke, D. G., Kanatzidis, M. G., & Wessels, B. W. (2016). Charge Transport Mechanisms in a Pb2P2Se6 Semiconductor. ACS Photonics, 3(10), 1877-1887. https://doi.org/10.1021/acsphotonics.6b00396