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Thallium lead iodide (TlPbI3) is a compound semiconductor characterized with wide bandgap (2.3 eV) and high photon stopping power. TlPbI3 is an attractive material for fabrication of room temperature radiation detectors. In this study, TlPbI3 crystals were grown by the vertical Bridgman technique using zone-purified materials. The starting materials for the crystal growth were synthesized from commercially available TlI and PbI2 powder with nominal purity of 99.99%. Powder X-ray diffraction analysis was performed to study chemical composition of the synthesized TlPbI3. In order to fabricate radiation detectors, the grown crystals were cut into several wafers using a wire saw. The wafers were then polished using Al2O3 abrasives. Electrodes were formed on the wafers by vacuum evaporation of gold. The resultant TlPbI3 radiation detectors were evaluated by measuring their current-voltage characteristics and spectral responses. Most TlPbI3 detectors exhibited resistivities higher than 1011Ωcm. The TlPbI3 detectors were irradiated with α-particles (5.48 MeV) from a 241Am source or γ-rays (122 keV) from a 57Co source. The TlPbI3 detectors exhibited a clear peak of 5.48 MeV α-particles. Although the 122 keV peak was not resolved in the energy spectra, increased counts above the noise spectrum were observed by the present detectors.
Date of Publication: Aug. 2003