Investigation of defect levels in Cs 2Hg 6S 7 single crystals by photoconductivity and photoluminescence spectroscopies

J. A. Peters, Nam Ki Cho, Zhifu Liu, B. W. Wessels, Hao Li, J. Androulakis, Mercouri G Kanatzidis

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The heavy element semiconductor compound Cs 2Hg 6S 7 is of interest as a potential wide gap semiconductor for gamma ray detection. To determine electrically active defects and their energy levels, photoconductivity (PC) spectroscopy was carried out over the temperature range of 90-295 K. The low temperature spectrum exhibits photoconductive transitions at 1.495, 1.61, 1.66, and 1.68 eV. The optical transitions are tentatively attributed to defects with levels located at energies of 50, 70, 120, and 240 meV from the band edge. A superlinear dependence of photocurrent on illumination intensity is observed that is attributed to a two-center recombination process that involves shallow traps and recombination centers. Near band edge photoluminescence (PL) was observed over the temperature range of 24-80 K. The spectrum revealed three defect related emission bands located at 1.68, 1.66, and 1.62 eV, whose ionization energies are 57 meV, 78 meV, and 115 meV, respectively. From the temperature and excitation dependencies of the observed peak intensities and energies, the radiative recombination mechanisms of the bands were attributed to transitions involving excitons bound to neutral and ionized acceptors. Good agreement of the defect level energies determined by PL and PC were noted, indicating that they were of the same origin. The defects were tentatively attributed to metal vacancies that form shallow acceptor levels.

Original languageEnglish
Article number063702
JournalJournal of Applied Physics
Volume112
Issue number6
DOIs
Publication statusPublished - Sep 15 2012

Fingerprint

photoconductivity
photoluminescence
single crystals
defects
spectroscopy
energy levels
heavy elements
radiative recombination
optical transition
temperature
photocurrents
energy
illumination
excitons
traps
gamma rays
ionization
metals
excitation

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Investigation of defect levels in Cs 2Hg 6S 7 single crystals by photoconductivity and photoluminescence spectroscopies. / Peters, J. A.; Cho, Nam Ki; Liu, Zhifu; Wessels, B. W.; Li, Hao; Androulakis, J.; Kanatzidis, Mercouri G.

In: Journal of Applied Physics, Vol. 112, No. 6, 063702, 15.09.2012.

Research output: Contribution to journalArticle

Peters, J. A. ; Cho, Nam Ki ; Liu, Zhifu ; Wessels, B. W. ; Li, Hao ; Androulakis, J. ; Kanatzidis, Mercouri G. / Investigation of defect levels in Cs 2Hg 6S 7 single crystals by photoconductivity and photoluminescence spectroscopies. In: Journal of Applied Physics. 2012 ; Vol. 112, No. 6.
@article{cb95b8e05e2a445b9ee4402f1a21a5b1,
title = "Investigation of defect levels in Cs 2Hg 6S 7 single crystals by photoconductivity and photoluminescence spectroscopies",
abstract = "The heavy element semiconductor compound Cs 2Hg 6S 7 is of interest as a potential wide gap semiconductor for gamma ray detection. To determine electrically active defects and their energy levels, photoconductivity (PC) spectroscopy was carried out over the temperature range of 90-295 K. The low temperature spectrum exhibits photoconductive transitions at 1.495, 1.61, 1.66, and 1.68 eV. The optical transitions are tentatively attributed to defects with levels located at energies of 50, 70, 120, and 240 meV from the band edge. A superlinear dependence of photocurrent on illumination intensity is observed that is attributed to a two-center recombination process that involves shallow traps and recombination centers. Near band edge photoluminescence (PL) was observed over the temperature range of 24-80 K. The spectrum revealed three defect related emission bands located at 1.68, 1.66, and 1.62 eV, whose ionization energies are 57 meV, 78 meV, and 115 meV, respectively. From the temperature and excitation dependencies of the observed peak intensities and energies, the radiative recombination mechanisms of the bands were attributed to transitions involving excitons bound to neutral and ionized acceptors. Good agreement of the defect level energies determined by PL and PC were noted, indicating that they were of the same origin. The defects were tentatively attributed to metal vacancies that form shallow acceptor levels.",
author = "Peters, {J. A.} and Cho, {Nam Ki} and Zhifu Liu and Wessels, {B. W.} and Hao Li and J. Androulakis and Kanatzidis, {Mercouri G}",
year = "2012",
month = "9",
day = "15",
doi = "10.1063/1.4750982",
language = "English",
volume = "112",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "6",

}

TY - JOUR

T1 - Investigation of defect levels in Cs 2Hg 6S 7 single crystals by photoconductivity and photoluminescence spectroscopies

AU - Peters, J. A.

AU - Cho, Nam Ki

AU - Liu, Zhifu

AU - Wessels, B. W.

AU - Li, Hao

AU - Androulakis, J.

AU - Kanatzidis, Mercouri G

PY - 2012/9/15

Y1 - 2012/9/15

N2 - The heavy element semiconductor compound Cs 2Hg 6S 7 is of interest as a potential wide gap semiconductor for gamma ray detection. To determine electrically active defects and their energy levels, photoconductivity (PC) spectroscopy was carried out over the temperature range of 90-295 K. The low temperature spectrum exhibits photoconductive transitions at 1.495, 1.61, 1.66, and 1.68 eV. The optical transitions are tentatively attributed to defects with levels located at energies of 50, 70, 120, and 240 meV from the band edge. A superlinear dependence of photocurrent on illumination intensity is observed that is attributed to a two-center recombination process that involves shallow traps and recombination centers. Near band edge photoluminescence (PL) was observed over the temperature range of 24-80 K. The spectrum revealed three defect related emission bands located at 1.68, 1.66, and 1.62 eV, whose ionization energies are 57 meV, 78 meV, and 115 meV, respectively. From the temperature and excitation dependencies of the observed peak intensities and energies, the radiative recombination mechanisms of the bands were attributed to transitions involving excitons bound to neutral and ionized acceptors. Good agreement of the defect level energies determined by PL and PC were noted, indicating that they were of the same origin. The defects were tentatively attributed to metal vacancies that form shallow acceptor levels.

AB - The heavy element semiconductor compound Cs 2Hg 6S 7 is of interest as a potential wide gap semiconductor for gamma ray detection. To determine electrically active defects and their energy levels, photoconductivity (PC) spectroscopy was carried out over the temperature range of 90-295 K. The low temperature spectrum exhibits photoconductive transitions at 1.495, 1.61, 1.66, and 1.68 eV. The optical transitions are tentatively attributed to defects with levels located at energies of 50, 70, 120, and 240 meV from the band edge. A superlinear dependence of photocurrent on illumination intensity is observed that is attributed to a two-center recombination process that involves shallow traps and recombination centers. Near band edge photoluminescence (PL) was observed over the temperature range of 24-80 K. The spectrum revealed three defect related emission bands located at 1.68, 1.66, and 1.62 eV, whose ionization energies are 57 meV, 78 meV, and 115 meV, respectively. From the temperature and excitation dependencies of the observed peak intensities and energies, the radiative recombination mechanisms of the bands were attributed to transitions involving excitons bound to neutral and ionized acceptors. Good agreement of the defect level energies determined by PL and PC were noted, indicating that they were of the same origin. The defects were tentatively attributed to metal vacancies that form shallow acceptor levels.

UR - http://www.scopus.com/inward/record.url?scp=84867047822&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84867047822&partnerID=8YFLogxK

U2 - 10.1063/1.4750982

DO - 10.1063/1.4750982

M3 - Article

VL - 112

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 6

M1 - 063702

ER -