Density functional study of the properties of Tl6SeI4 for radiation detection applications

The extra compositional freedom available in ternary compounds allow flexibility to tune their electronic and structural properties compared to the binary counterparts. Indeed, the Tl-based ternary semiconductor Tl6SeI4 is a promising candidate for radiation detectors. It has a band gap (1.86 eV) that is intermediate between those of Tl2Se (0.6 eV) and TlI (2.75 eV) and suitable for room temperature detectors. However, the flexibility in ternary semiconductors may come at the expense of more channels for defect formation and more complex defect chemistry, which need to be studied in details. To better understand the properties of Tl6SeI4$_{\mathrm{\thinspace }}$in relation to the radiation detection, we performed first-principles study of electronic structure, phase diagram, and dielectric, optical, and defect properties in Tl$_{\mathrm{6}}$SeI$_{\mathrm{4}}$.[1] We will discuss the properties of defects and their diffusion barriers in the context of resistivity and polarization phenomenon in Tl6SeI4. [1] K. Biswas, M.-H. Du, and D. J. Singh, \quad Phys. Rev. B \quad \textbf{86}, 144108 (2012).