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 language | English |
|---|---|
| Article number | 063702 |
| Journal | Journal of Applied Physics |
| Volume | 112 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - Sep 15 2012 |
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- Physics and Astronomy(all)
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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 journal › Article
}
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.
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U2 - 10.1063/1.4750982
DO - 10.1063/1.4750982
M3 - Article
AN - SCOPUS:84867047822
VL - 112
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 6
M1 - 063702
ER -