Title :
Characterization of Stress in Thallium Bromide Devices
Author :
Datta, Amlan ; Motakef, Shariar
Author_Institution :
CapeSym Inc., Natick, MA, USA
Abstract :
Thallium bromide (TlBr) is a wide bandgap, compound semiconductor with high gamma-ray stopping power and promising physical properties. Several surface modification techniques have been demonstrated to increase the lifetime of TlBr devices at room temperature. However, absence of reproducibility in the performance of TlBr detectors (even with low ionic conduction at -20°C) suggests presence of unexplored bulk phenomena. Stress in the TlBr crystal due to various intrinsic (e.g. grain boundaries and dislocations networks) in conjunction with external factors such as thermal, mechanical, and electrical loadings explains detector-to-detector variations. Photoelasticity and opto-electrical techniques were applied to visualize and qualitatively correlate the device performance with stress. Changes in stress patterns with variations in ambient temperature were clearly demonstrated. Electric field fluctuations in TlBr detectors with time were for the first time observed using the Pockels effect.
Keywords :
gamma-ray apparatus; gamma-ray detection; thallium; thallium compounds; Pockels effect; TlBr crystal; TlBr detectors; detector-to-detector variations; electric field fluctuations; gamma-ray stopping power; opto-electrical techniques; photoelasticity techniques; stress characterization; surface modification techniques; thallium bromide devices; unexplored bulk phenomena; Color; Crystals; Detectors; Electrodes; Performance evaluation; Residual stresses; Birefringence; bulk defects; dislocations; extended defects; ionic polarization; long term performance; photoelasticity; pockels effect; semiconductor crystal growth; semiconductor device breakdown; semiconductor radiation detectors; stress analysis; tlBr detectors; tlBr device lifetime; wide band gap semiconductors;
Journal_Title :
Nuclear Science, IEEE Transactions on
DOI :
10.1109/TNS.2015.2400396