2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Cadmium Zinc Telluride (CZT) Nanowire Sensors for Detection of Low Energy Gamma Ray Detection

T. Gandhi, P. Dzurella, K.S. Raja, I. Chatterjee and M. Misra
Univ of Nevada Reno, US

nanowire, gamma ray detection, cadmium zinc telluride, TiO2

Gamma ray detectors have become increasingly important for the long term monitoring of nuclear waste storage sites, environmental safety, and homeland security against terrorist threats. Commercially single crystals of CdZnTe or CdTe compound semiconductors developed by bridgman technique has been used for detection of gamma rays. In order to increase the detection efficiency a large volume of detector material with low defect density is required to increase the detection efficiency. Making CZT of detector quality through conventional process is expensive. We have synthesized CZT nanowire arrays which can be used for detecting low energy radiation and has been reported for the first time. The CZT nanowire arrays were grown on nanotubular TiO2 template in a non-aqueous bath using pulsed electrodeposition technique at 130 C (as shown in Figure1). The XRD characterization showed the compound formation of the CZT nanowires (Figure 2). The electrical resistivity of the CZT nanowires were in the order of 1010 -cm. Such high resistivity is attributed to the presence of deep defect states such as cadmium vacancies created by the anodic cycle of the pulse electrodeposition process. Stack of 5 CZT samples were connected in series and different bias potentials were applied. The leakage current was in the order of tens of PicoAmperes. When the stack of 5 samples was introduced to Am-241 having energy of 60KeV, the current in the circuit increased by 100-200% compared to the background current shown in figure 3.The preliminary results indicate that the CZT nanowire arrays can be used as a gamma ray detector material at room temperature with much low bias potential (1-3V) as against 300-500V applied to the conventional bulk crystals.

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