Characterization of Al-Schottky CdTe detectors

Abstract

In the last decades, great efforts are being devoted to the development of CdTe detectors for high resolution X-ray and gamma ray spectroscopy. Recently, new rectifying contacts based on aluminum (Al) are very appealing in the development of CdTe detectors with low leakage currents and anode pixellization. In this work, we report on preliminary results of electrical and spectroscopic investigations on Schottky CdTe diode detectors (4.1 × 4.1 × 0.75 and 4.1 × 4.1 × 2 mm3) with Au/Ti/Al/CdTe/Pt electrode configuration. The detectors are characterized by very low leakage currents even at room temperature (26 pA at 25 °C under a bias voltage of −100 V for the 2 mm thick detector). Polarization phenomena, typical of CdTe diode detectors, were investigated through electrical and spectroscopic approaches, pointing out the influence of the bias voltage, the temperature and the detector thickness. Good time stability, during a short-term operation of one hour, was observed for both detectors at temperatures below 10 °C and by using an electric field of 5000 V/cm. The detectors exhibited good energy resolution of 1.5 keV (FWHM) at 59.5 keV (T=−25 °C) by using a standard electronic chain. This work was carried out in the framework of the development of portable X-ray spectrometers for both laboratory research and medical applications.