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KMID : 0364920160410020167
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Journal of Radiation Protection and Research
2016 Volume.41 No. 2 p.167 ~ p.171
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Optical Characterizations of TlBr Single Crystals for Radiation Detection Applications
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Oh Joon-Ho
Kim Dong-Jin
Kim Han-Soo
Lee Seung-Hee
Ha Jang-Ho
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Abstract
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Background: TlBr is of considerable technological importance for radiation detection applications where detecting high-energy photons such as X-rays and γ-rays are of prime importance. However, there were few reports on investigating optical properties of TlBr itself for deeper understandings of this material and for making better radiation detection
devices. Thus, in this paper, we report on the optical characterizations of TlBr single crystals. Spectroscopic ellipsometry (SE) and photoluminescence (PL) measurements at RT were performed for this work.
Materials and Methods: A 2-inch TlBr single crystalline ingot was grown by using the vertical Bridgman furnace. SE measurements were performed at RT within the photon energy range from 1.1 to 6.5 eV. PL measurements were performed at RT by using a home-made PL system equipped with a 266 nm-laser and a spectrometer.
Results and Discussion: Dielectric responses from SE analysis were shown to be slightly different among the different samples possibly due to the different structural/optical properties. Also from the PL measurements, it was observed that the peak intensities of the middle samples were significantly higher than those of the other two samples. With the given values for permittivity of free space (ε0 = 8.854x10-12 F·m-1), thickness (d = 1mm), and area (A = 10x10 mm2) of the TlBr sample, capacitances of TlBr were 6.9 pF (at hν = 3 eV) and 4.4 pF (at hν = 6 eV), respectively.
Conclusion: SE and PL measurement and analysis were performed to characterize TlBr samples from the optical perspective. It was observed that dielectric responses of different TlBr samples were slightly different due to the different material properties. PL measurements showed that the middle sample exhibited much stronger PL emission peaks due to
the better material quality. From the SE analysis, optical, dielectric constants were extracted, and calculated capacitances were in the few pF range.
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KEYWORD
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Radiation detectors, Semiconductor single crystals, Spectroscopic ellipsometry, Photoluminescence
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