Koushik Biswas — Page 3

arXiv2012

Energy Transport and Scintillation of Cerium Doped Elpasolite Cs2LiYCl6: Hybrid Density Functional Calculations

Elpasolites are a large family of halides which have recently attracted considerable interest for their potential applications in room-temperature radiation detection. Cs2LiYCl6 is one of the most widely studied elpasolite scintillators. In this paper, we will show hybrid density functional calculations on electronic structure, energetics of small electron and hole polarons and self-trapped excitons, and the excitation of luminescence centers (Ce impurities) in Cs2LiYCl6. The results provide important understanding in energy transport and scintillation mechanisms in Cs2LiYCl6 and rare-earth elpasolites in general.

cond-mat.mtrl-sci↗

arXiv2012

What Causes High Resistivity in CdTe

CdTe can be made semi-insulating by shallow donor doping. This is routinely done to obtain high resistivity in CdTe-based radiation detectors. However, it is widely believed that the high resistivity in CdTe is due to the Fermi level pinning by native deep donors. The model based on shallow donor compensation of native acceptors was dismissed based on the assumption that it is practically impossible to control the shallow donor doping level so precisely that the free carrier density can be brought below the desired value suitable for radiation detection applications. In this paper, we present our calculations on carrier statistics and energetics of shallow donors and native defects in CdTe. Our results show that the shallow donor can be used to reliably obtain high resistivity in CdTe. Since radiation detection applications require both high resistivity and good carrier transport, one should generally use shallow donors and shallow acceptors for carrier compensation and avoid deep centers that are effective carrier traps.

cond-mat.mtrl-sci↗