Large area thallium bromide semiconductor radiation detectors with thallium contacts

Amlan Datta; Piotr Becla; Shariar Motakef

doi:10.1117/12.2319351

13 September 2018 Large area thallium bromide semiconductor radiation detectors with thallium contacts

Amlan Datta, Piotr Becla, Shariar Motakef

Proceedings Volume 10762, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XX; 107620X (2018) https://doi.org/10.1117/12.2319351
Event: SPIE Optical Engineering + Applications, 2018, San Diego, California, United States

Abstract

Thallium bromide (TlBr) is a wide bandgap, compound semiconductor with high gamma-ray stopping power and promising physical properties. Large single crystalline defect-free Bridgman boules of 2-inches in diameter were grown for fabricating high Figure of Merit (defined under SIGMA program) radiation detectors for homeland security applications. However, the electro-migration of Br- ions towards anode and their reaction with the contact have long been known to adversely influence the lifetime of TlBr devices. We report on the performance of TlBr devices with Tl-contacts which minimizes the effects of polarization. Results indicate that vapor-deposited Tl-contacts are highly ohmic. Unlike devices with Pt and Au contacts, devices with Tl-contacts do not exhibit the short term (100s of hours) fluctuations in the spectroscopic response. A significant reduction of polarization even before device conditioning is clearly observed in detectors with Tl-contacts. Furthermore, these devices show a stable behavior and can work under much lower electric fields. Energy resolution in the range of 2-2.5% at 662keV was obtained using virtual Frisch-grid (10mm thick) and pixelated (5.5mm thick) TlBr devices with Tl-contacts without any digital correction. Large area 20mm x 20mm x 5.5mm pixelated detectors with 11×11 and 15×15 pixel patterns were also fabricated using Tl-contacts. The planar Tl-contact devices exhibited a stable gamma detection performance for up to 14-months under continuous bias (~1000 V/cm) and irradiation.

Citation Download Citation

Amlan Datta, Piotr Becla, and Shariar Motakef "Large area thallium bromide semiconductor radiation detectors with thallium contacts", Proc. SPIE 10762, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XX, 107620X (13 September 2018); https://doi.org/10.1117/12.2319351

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