Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session H11: Dopants and Defects in Semiconductors - 2D, Nano, and Novel Materials
2:30 PM–5:30 PM,
Tuesday, March 6, 2018
LACC Room: 303A
Sponsoring Units: DMP DCOMP FIAP
Chair: Cyrus Dreyer, Rutgers Univ
Abstract: H11.00011 : Effect of Impurities on Properties of Tl6SeI4 Semiconductor for Hard Radiation Detection
4:54 PM–5:06 PM
The semiconductor Tl6SeI4 is a promising candidate material for room temperature X-ray and γ-ray detection. The carrier transport and detection performance strongly depend on concentration of impurity levels acting as carrier trapping and scattering centers. The main impurities in Tl6SeI4 were identified as O, C, Si, Sn, Al, Pb, Bi, Cl, Br, S and Te. To assess the effect of impurities on detector performance, theoretical calculations were performed based on first-principles density functional theory (DFT) including nonlocal exchange-correlation functionals. The results show that Al and Bi introduce deep defect levels in the band gap and can be detrimental to the detector performance of Tl6SeI4. Si impurities can act as deep donors if Tl6SeI4 is grown in Tl-rich/Se-poor conditions, but become electrically benign in Tl-poor/Se-rich conditions, Pb and Sn are shallow donors, and Cl, Br, S, Te impurities are inactive. Interstitial O introduces trapping levels near the middle of the gap, but will become electrically inactive if its concentration is reduced below the level of intrinsic Se vacancies, in which case O atoms will occupy Se sites. The effect of various chemical environments on defect properties was examined and the optimal conditions for material synthesis were suggested.
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