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 language | English |
|---|---|
| Pages (from-to) | 1877-1887 |
| Number of pages | 11 |
| Journal | ACS Photonics |
| Volume | 3 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 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
Charge Transport Mechanisms in a Pb2P2Se6 Semiconductor. / Kostina, Svetlana S.; Hanson, Micah P.; Wang, Peng L.; Peters, John A.; Valverde-Chávez, David A.; Chen, Pice; Cooke, David G.; Kanatzidis, Mercouri G; Wessels, Bruce W.
In: ACS Photonics, Vol. 3, No. 10, 19.10.2016, p. 1877-1887.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Charge Transport Mechanisms in a Pb2P2Se6 Semiconductor
AU - Kostina, Svetlana S.
AU - Hanson, Micah P.
AU - Wang, Peng L.
AU - Peters, John A.
AU - Valverde-Chávez, David A.
AU - Chen, Pice
AU - Cooke, David G.
AU - Kanatzidis, Mercouri G
AU - Wessels, Bruce W.
PY - 2016/10/19
Y1 - 2016/10/19
N2 - 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.
AB - 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.
KW - charge transport
KW - conductivity
KW - deep levels
KW - terahertz spectroscopy
KW - transient spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=84992184482&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84992184482&partnerID=8YFLogxK
U2 - 10.1021/acsphotonics.6b00396
DO - 10.1021/acsphotonics.6b00396
M3 - Article
AN - SCOPUS:84992184482
VL - 3
SP - 1877
EP - 1887
JO - ACS Photonics
JF - ACS Photonics
SN - 2330-4022
IS - 10
ER -