Microstructure And Microhardness Of TlBr Detector Crystals

Full text: TlBr single crystal is a promising candidate as a room temperature X-ray and gamma quantum detector due to its high atomic number (Tl-81, Br-35), high density (ρ=7.56 g/cm3) and wide band gap (≅ 2.75 eV). However, the TlBr detectors up to now are not in commercial use due to their non-stability. The main factors affecting the sensitivity and energy resolution of detectors are the charge carrier collection efficiency on detector surface, crystal purity, quality of crystal surface and contact electrodes. Therefore, the developing of surface preparation technologies and investigations of surface microstructure and morphology of TlBr crystals are actual problems. In this work the effect of mechanical processing and chemical etching on crystal surface was studied. The optical microscopy and microhardness methods were used for surface quality estimation. The obtained results were compared with the spectrometric properties of detectors. The procedures of chemical etching were developed, which ensure removing of mechanically destroyed surface layer and surface processing for deposition of contact electrodes preparing of surfaces layer. The quality of crystals presented by different providers was compared. It is shown that microstructure analysis by optical microscopy and microhardness methods can be successfully used for surface quality characterizationand enhancement of detector manufacturing technology. (Authors)