Study of gamma-ray detector performance of Cd1-xZnxTe crystal treated by different etchants

Radiation detectors have been fabricated from Cd1-xZnxTe crystals and their performance has been studied with respect to their Cd1-xZnxTe surface preparation. Energy resolution, leakage current, resistivity, ohmicity as well as surface roughness of the detectors were measured and compared for various chemical treatments. Etching in lactic acid has been found to lead to better ohmic contact, a rougher surface and higher leakage current. Bromine is effective in removing the damaged layer and when added to 20% lactic acid in ethylene glycol leads to a lower leakage current and consequently a better energy resolution. The best detector performance was obtained with a two step treatment consisting of a standard etchant (5% Br in methanol) followed by 2% Br in 20% lactic acid in ethylene glycol. The results clearly demonstrate the importance of surface chemical treatments in the fabrication of Cd1-xZnxTe radiation detectors