Highly sensitive g-radiation detectors operating at room temperature are greatly desired for national security and non-proliferation applications. Semiconductors with wide band gaps and high densities provide higher energy resolution than scintillator materials. Currently only a few materials are used (Cd1-xZnxTe (CZT), HgI2, and TlBr) with CZT being the leading one. As a new approach to discover high performance g-ray detectors, a family of ternary metal chalcohalides was developed as a bulk semiconductor which has significant advantages compared to other types of detector materials in device engineering as well as detection efficiency. This talk will present a few promising semiconductors including CsPbBr3, Pb7S2Br10, A3Bi2X9 (A = Cs, Rb; X = Br, I), and Hg3Q2X2 (Q = S, Se, Te; X = Cl, Br, I) down-selected by the density (&gt; 5 g/cm3), band gap (1.5 – 2.5 eV), resistivity (&gt;109 Ohm.cm), and mobility-lifetime (μ.τ) product (&gt;10-4 cm2/V) necessary for good detector materials. In the experimental process, however, phase transition, decomposition during thermal process, and critically the carrier traps caused by various types of defects and impurities are the practical challenges to achieve highly pure defect-free single phase materials. We will discuss the optimized conditions in synthesis, purification, and crystal growth and the assessment for g-ray detectors based on the resistivity, μ.τ, photoluminescence, and g-ray spectroscopy as well as their fundamental physical properties.

Metal chalcohalides as promising candidate semiconductors for g-ray detection

251st National Meeting (2016)

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