Elucidation of Charge Trapping Levels in TlBr and Development of a Total Absorption gamma ray Energy Spectrometer

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12532
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 80040:Quantum beam science-related
• Research Institution: Hokkaido University
• Principal Investigator: Kaneko Junichi 北海道大学, 工学研究院, 准教授 (90333624)
• Co-Investigator(Kenkyū-buntansha): 人見 啓太朗 東北大学, 工学研究科, 准教授 (60382660)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: TlBr / 半導体検出器 / 結晶育成 / 電極 / ドーピング

Outline of Final Research Achievements

Various gases were investigated for the synthesis atmosphere of TlBr crystals. The sample synthesis atmosphere was chemically synthesized and adjusted to be safe and stable, especially for highly corrosive gases. A clear 662 keV total absorption peak was obtained from the fabricated TlBr detector. The feasibility of doping an ohmic electrode as a method to suppress the charge storage near the electrode of the detector was experimentally verified: 5-8 times higher current was observed for the SrBr2-doped sample and about 3 times higher for the PbBr2-doped sample. Photo irradiation I-V measurement test: A photo irradiation IV measurement system was fabricated to identify the capture level of charge carriers in TlBr crystal, and the response current was observed around 460 nm, which corresponds to the band gap of TlBr of 2.68 eV.

Free Research Field

放射線計測

Academic Significance and Societal Importance of the Research Achievements

PETやSPECTへの応用が期待されるTlBr半導体検出器の開発と電荷捕獲準位を同定する光I-V測定装置の開発を行った。TlBr単結晶工程の改良を進め、全吸収ピークを観測できる結晶の育成に成功した。また電極でのチャージアップを防ぐ方法として、ドーピングにかかわる実験を行い、いくつかの候補を発見し知財を申請した。さらに捕獲準位を同定する装置開発をを行い、初期的な測定に成功した。