Optical Characterizations of TlBr Single Crystals for Radiation Detection Applications

Title & Authors
Optical Characterizations of TlBr Single Crystals for Radiation Detection Applications
Oh, Joon-Ho; Kim, Dong Jin; Kim, Han Soo; Lee, Seung Hee; Ha, Jang Ho;

Abstract
Background: TlBr is of considerable technological importance for radiation detection applications where detecting high-energy photons such as X-rays and $\small{{\gamma}}$-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 (${\varepsilon}_0 Keywords Radiation detectors;Semiconductor single crystals;Spectroscopic ellipsometry;Photoluminescence; Language English Cited by References 1. Kostamo P, et al. Characterization of TlBr for X-ray and$\gamma$-ray detector applications. Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. 2009;607:129-131. 2. Kouznetsov MS, Lisitsky IS, Zatoloka SI, and Gostilo VV. Development of the technology for growing TlBr detector crystals. Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. 2004;531:174-180. 3. Hitomi K, Matsumoto M, Muroi O, Shoji T, and Hiratate Y. Characterization of thallium bromide crystals for radiation detector applications. J. Cryst. Growth. 2001;225:129-133. 4. Hitomi K, Onodera T, and Shoji T. Influence of zone purification process on TlBr crystals for radiation detector fabrication. Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. 2007;579:153-156. 5. Kim DJ, et al. Characteristics of TlBr single crystals grown using the vertical Bridgman-Stockbarger method for semiconductor-based radiation detector applications. Mater. Sci. In press. 6. Fujiwara H, Koh J, Rovira PI, and Collins RW. Assessment of effective-medium theories in the analysis of nucleation and microscopic surface roughness evolution for semiconductor thin films. Phys. Rev. B. 2000;61:10832-10844. 7. Kim TJ, Hwang SY, Byun JS, Diware MS, Choi J, Park HG, and Kim YD, Temperature dependence of the dielectric functions and the critical points of InSb by spectroscopic ellipsometry from 31 to 675 K. J. Appl. Phys. 2013;114:103501.1-103501.5. 8. Kim TJ, Ghong TH, Kim YD, Kim SJ, Aspnes DE, Mori T, Yao T, and Koo BH. Dielectric functions of$In_xGa_{1-x}As$alloys. Phys. Rev. B. 2003;68:115323.1-115323.10. 9. Price J, Hung PY, Rhoad T, Foran B, and Diebold AC. Spectroscopic ellipsometry characterization of$Hf_xSi_yO_z$films using the Cody-Lorentz parameterized model. Appl. Phys. Lett. 2004;85:1701-1704. 10. Zhang XT, et al. Structure and optically pumped lasing from nanocrystalline ZnO thin films prepared by thermal oxidation of ZnS thin films. J. Appl. Phys. 2002;92:3293-3298. 11. Giri PK, Bhattacharyya S, Kesavamoorthy R, Panigrahi BK, and Nair KGM. Intense ultraviolet-blue photoluminescence from$SiO_2$embedded Ge nanocrystals prepared by different techniques. J. Nanosci. Nanotechnol. 2009;9:1-7. 12. Hayakawa K, Hitomi K, Shoji T, and Onodera C. Photoluminescence analysis of TlBr crystals for radiation detector applications. 2009 IEEE Nuclear Science Symposium Conference, Orlando USA. October 24-November 1, 2015. 13. Fujii A, Ueda H, Tabuki M, Miyazaki K. Extrinsic self-trapping of excitons in TlBr(I). J. Luminescence. 2005;112:84-87. 14. Bolton W. Capacitance, Engineering science. 5th Ed. Philadelphia NY. Springer. 2006;161. 15. Wang YJ, Patt BE, Iwanczyk JS. High efficiency$CsI(TI)/HgI_2\$ gamma ray spectrometers. IEEE Trans. Nucl. Sci. 1995;42:601-605.