Defect Antiperovskite Compounds Hg3Q2I2 (Q = S, Se, and Te) for Room-Temperature Hard Radiation Detection

Journal of the American Chemical Society

5 years ago

Defect Antiperovskite Compounds Hg3Q2I2 (Q = S, Se, and Te) for Room-Temperature Hard Radiation Detection

Yihui He, Svetlana S. Kostina, Oleg Y. Kontsevoi, Giancarlo G. Trimarchi, Saiful M. Islam, Mercouri G. Kanatzidis, Sanjib Das, Constantinos C. Stoumpos, Wenwen Lin, Bruce W. Wessels, Joon-Il Kim, Zhifu Liu

The high Z chalcohalides Hg₃Q₂I₂ (Q = S, Se, and Te) can be regarded as of antiperovskite structure with ordered vacancies and are demonstrated to be very promising candidates for X- and γ-ray semiconductor detectors. Depending on Q, the ordering of the Hg vacancies in these defect antiperovskites varies and yields a rich family of distinct crystal structures ranging from zero-dimensional to three-dimensional, with a dramatic effect on the properties of each compound. All three Hg₃Q₂I₂ compounds show very suitable optical, electrical, and good mechanical properties required for radiation detection at room temperature. These compounds possess a high density (>7 g/cm³) and wide bandgaps (>1.9 eV), showing great stopping power for hard radiation and high intrinsic electrical resistivity, over 10¹¹ Ω cm. Large single crystals are grown using the vapor transport method, and each material shows excellent photo sensitivity under energetic photons. Detectors made from thin Hg₃Q₂I₂ crystals show reasonable response under a series of radiation sources, including ²⁴¹Am and ⁵⁷Co radiation. The dimensionality of Hg–Q motifs (in terms of ordering patterns of Hg vacancies) has a strong influence on the conduction band structure, which gives the quasi one-dimensional Hg₃Se₂I₂ a more prominently dispersive conduction band structure and leads to a low electron effective mass (0.20 m₀). For Hg₃Se₂I₂ detectors, spectroscopic resolution is achieved for both ²⁴¹Am α particles (5.49 MeV) and ²⁴¹Am γ-rays (59.5 keV), with full widths at half-maximum (FWHM, in percentage) of 19% and 50%, respectively. The carrier mobility-lifetime μτ product for Hg₃Q₂I₂ detectors is achieved as 10^–5–10^–6 cm²/V. The electron mobility for Hg₃Se₂I₂ is estimated as 104 ± 12 cm²/(V·s). On the basis of these results, Hg₃Se₂I₂ is the most promising for room-temperature radiation detection.

Publisher URL: http://dx.doi.org/10.1021/jacs.7b03174

DOI: 10.1021/jacs.7b03174