Technology And Properties Of CdZnTe Detector

There is presently a widespread need for room temperature gamma and X-ray imaging capability for both medical and industrial applications . The interest toward the use of CdZnTe detector was greatly increased in the recent years because they offer a good trade-off between key perfonnance,such as the energy resolution and the absorption efficiency.and the complexity of the experimental equipment.Cadimium Zinc Telluride(CdZnTe) is one of the ternary semiconducting compounds of II-VI type which crystallize in the zinc blende structure (symmetry F-43m).Because of its high resistivity(1011 /cm)),high atomic number(48,52),strong energy resolution ability to x-ray,and Y -ray,wide energy gap which can vary from 1.4eV to 2.26eV while the x changes. A wide range of application is possiblerfrom biomedical and industrial imaging to radiation monitoring and control due to their well-known capability to operate at room temperature with minor degradation of spectroscopic performance. It is used in solar cells and semiconductor detectors for astrophysical research,for x-ray fluorescence(XRF) analysis,industrial gauging,nuclear proliferation treaty verifaction et.al,and also in laser window and infrared array technology as subtriate for Hg1-xCdxTe.Cd1-xZnxTe Single crystal with good crystallinity has been grown by the descending ampoule with rotation method-Beforethis,high-purity Cd1-xZnxTe polycrystal materials have been synthesized from 6N Gd Zn Te in the same ampoule.On the Basis of this,we deeply explore method of detector fabrication.And we also studied the level and density of traps in detector.Gold,indium and C have been deposited as electrodes on polished and chemically etched surfaces of samples with the sizes from 5×5×1 to 10×10×1.5mm to compare different contact technologies.The behavior of detector'sleakage current with temperature and leakage current with time were studied as well as th current-voltage characteristics to deduce the level and density of trap in detectors.The results show that crystal inhomogeneities and suitable contacts are critical to the fabrication of high quality CdZnTe spectrometers.The modified growth technique is a new and promising method for growing highly pure and perfect CdZnTe single crystals.Good quality ohmic contact detectors are achieved when gold or indiumare deposited as electrodes on polished and chemically etched surface.