Fabrication of Small-Pixel CdZnTe Sensors and Characterization with X-rays

Abstract

Over the past few years, sensors made from high-Z compound semiconductors have attracted quite some attention for use in applications which require the direct detection of X-rays in the energy range 30–100 keV. One of the candidate materials with promising properties is cadmium zinc telluride (CdZnTe). In the context of this article, we have developed pixelated sensors from CdZnTe crystals grown by Boron oxide encapsulated vertical Bridgman technique. We demonstrate the successful fabrication of CdZnTe pixel sensors with a fine pitch of 55 m and thickness of 1 mm and 2 mm. The sensors were bonded on Timepix readout chips to evaluate their response to X-rays provided by conventional sources. Despite the issues related to single-chip fabrication procedure, reasonable uniformity was achieved along with low leakage current values at room temperature. In addition, the sensors show stable performance over time at moderate incoming fluxes, below 106 photons mm−2s−1.

High performance platinum contacts on high-flux CdZnTe detectors

“…The first attempts in realising blocking contacts on this material by means of the technique developed at IMEM-CNR, i.e., gold electroless deposition technique from alcoholic solutions 13 , were unsuccessful. This deposition technique allowed to obtain performing and robust contacts on both boron-encapsulated vertical-Bridgman grown CZT and Redlen LF-CZT, as shown in previous publications 18 – 20 , but producing sensors with extremely high leakage currents even at low bias voltage when used on HF-CZT. The platinum electroless contacts developed by IMEM-CNR and reported in Bettelli et al 16 were also tested.…”