Development of Gold Contacted Flip-chip Detectors with IMARAD CZT

Abstract

We present initial results from our evaluation of a gold-contacted pixellated detector using cadmium zinc telluride substrate produced by IMARAD Imaging Systems. The Horizontal Bridgman (HB) grown crystals from IMARAD have been shown to produce high resolution photopeaks, but they are also seen to have large leakage current. Our previous tests with IMARAD CZT showed that the use of indium anodes and gold cathode improved the resistivity compared to the standard indium-contacted detectors. We seek to test whether simple evaporated gold contacts alone could also reduce the leakage current and thus improve the spectral resolution, especially in the 10-100 keV energy range. We have fabricated several metal-semiconductor-metal (MSM) detectors with a 4x4 array of pixels on 10x10 mm substrates. Measurements of the detectors' leakage current, spectral response, and temperature sensitivity are presented and compared to IMARAD's ohmic contact detector and gold contact MSM detectors made of High Pressure Bridgman (HPB) material. Finally, we show preliminary results from a tiled flip-chip pixellated detector made using the IMARAD detectors.