Defect Antiperovskite Compounds Hg 3 Q 2 I 2 (Q = S, Se, and Te) for Room-Temperature Hard Radiation Detection

• Published in: Journal of the American Chemical Society Vol. 139; no. 23; pp. 7939 - 7951
• Main Authors: He, Yihui, Kontsevoi, Oleg Y, Stoumpos, Constantinos C, Trimarchi, Giancarlo G, Islam, Saiful M, Liu, Zhifu, Kostina, Svetlana S, Das, Sanjib, Kim, Joon-Il, Lin, Wenwen, Wessels, Bruce W, Kanatzidis, Mercouri G
• Format: Journal Article
• Language: English
• Published: United States 14.06.2017
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.7b03174

The high Z chalcohalides Hg Q I (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 Hg Q I 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/cm ) and wide bandgaps (>1.9 eV), showing great stopping power for hard radiation and high intrinsic electrical resistivity, over 10 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 Hg Q I crystals show reasonable response under a series of radiation sources, including Am and Co 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 Hg Se I a more prominently dispersive conduction band structure and leads to a low electron effective mass (0.20 m ). For Hg Se I detectors, spectroscopic resolution is achieved for both Am α particles (5.49 MeV) and Am 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 Hg Q I detectors is achieved as 10 -10 cm /V. The electron mobility for Hg Se I is estimated as 104 ± 12 cm /(V·s). On the basis of these results, Hg Se I is the most promising for room-temperature radiation detection.