Cu 2 I 2 Se 6 : A Metal-Inorganic Framework Wide-Bandgap Semiconductor for Photon Detection at Room Temperature

• Published in: Journal of the American Chemical Society 2018-02, Vol.140 (5), p.1894-1899
• Main Authors: Lin, Wenwen, Stoumpos, Constantinos C, Kontsevoi, Oleg Y, Liu, Zhifu, He, Yihui, Das, Sanjib, Xu, Yadong, McCall, Kyle M, Wessels, Bruce W, Kanatzidis, Mercouri G
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.7b12549

Cu I Se is a new wide-bandgap semiconductor with high stability and great potential toward hard radiation and photon detection. Cu I Se crystallizes in the rhombohedral R3̅m space group with a density of d = 5.287 g·cm and a wide bandgap E of 1.95 eV. First-principles electronic band structure calculations at the density functional theory level indicate an indirect bandgap and a low electron effective mass m * of 0.32. The congruently melting compound was grown in centimeter-size Cu I Se single crystals using a vertical Bridgman method. A high electric resistivity of ∼10 Ω·cm is readily achieved, and detectors made of Cu I Se single crystals demonstrate high photosensitivity to Ag Kα X-rays (22.4 keV) and show spectroscopic performance with energy resolutions under Am α-particles (5.5 MeV) radiation. The electron mobility is measured by a time-of-flight technique to be ∼46 cm ·V ·s . This value is comparable to that of one of the leading γ-ray detector materials, TlBr, and is a factor of 30 higher than mobility values obtained for amorphous Se for X-ray detection.