From Event: SPIE Optical Engineering + Applications, 2016
Thallium based chalcogenide and halide semiconductors such as Tl4HgI6, TlGaSe2, Tl6SeI4 and Tl6SI4 are promising materials for room-temperature hard radiation detection. They feature appropriate band gaps, high mass densities and facile growth technology. However, these materials are being plagued by the Tl oxides impurity from Tl precursor or Tl containing binary precursors, which leads to problems including tube breakage, parasitic nucleation and detector performance deterioration. In this work, we present a facile way to chemically reduce Tl oxidations, and then eliminate oxygen impurity by adding high-purity graphite powder during synthesis and crystal growth. We also further investigated the reactivity between Tl oxides and graphite. The detector performance of Tl6SeI4 crystal was dramatically improved after lowering/removing the oxygen impurities. This result not only indicates the significance of removing oxygen impurity for improving detector performance. Our results suggest that the chemical reduction method we developed by adding carbon powder during synthesis is highly effective in substantially reducing oxygen impurities from Tl containing materials.
Wenwen Lin, Zhifu Liu, Alexei V. Churilov, Yihui He, Hadong Kim, Leonard J. Cirignano, Christos D. Malliakas, Hao Li, Constantinos C. Stoumpos, Duck Young Chung, Bruce W. Wessels, and Mercouri G. Kanatzidis, "Strategy on removing oxygen impurity for crystal growth of one candidate Tl6SeI4 for room-temperature hard radiation detector(Conference Presentation)," Proc. SPIE 9968, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVIII, 99681A (Presented at SPIE Optical Engineering + Applications: August 31, 2016; Published: 2 November 2016); https://doi.org/10.1117/12.2237941.5178382271001.
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