Speaker
Dr
Vasilij Kozlov
(University of Helsinki, Finland)
Description
The single crystal TlBr is a promising candidate as a gamma-ray
detector due to its high stopping power, density (7.56 g/cm3) and
bandgap (2.68 eV). These properties allow to perform a compact
device working at room temperature. However, the transport
properties of TlBr were still plagued by material problems [1].
These problems are manly arisen from purity and quality of the
crystal, both these properties being actively affected by the total
process of detector manufacturing.
The study of initial stages of the process, namely the synthesis,
crystal growth and purification, has shown the considerable
variation in the material properties in respect of methods used [2].
The annealing was shown to improve the crystal quality of TlBr [3]
and its purity [2], and as result the electrical, optical and X-ray
properties became better. However, the electrical characteristics of
the samples were time depended and not fully understood.
In this work, the making of electric contact with different methods
was studied. Al, Ti, Cr, In, Sn, as well Ag- and graphite-paste were
used for annealed TlBr single crystals. I-V and C-V curves were
recorded. The samples were additionally characterised by x-ray
rocking curve method, photocurrent measurements and under polarised
light. They were also studied under Cu-radiation of x-ray powder
diffractometer.
References
[1] – A. Owens and A. Peacock, Nucl. Instr. and Meth. A 531, 18
(2004)
[2] – V. Kozlov, M. Leskelä, T. Prohaska, G. Schultheis, G.
Stingeder, H. Sipilä, Nucl. Instr. and Meth. A 531, 165 (2004)
[3] – V. Kozlov, M. Leskelä, H. Sipilä, Nucl. Instr. and Meth. A
546, 200 (2005)
Primary author
Dr
Vasilij Kozlov
(University of Helsinki, Finland)
