Effects of electrode fabrication on electrical properties of CdMgTe room temperature radiation detectors

Abstract

Cd1-xMgxTe (CdMgTe) is an ideal alternative material for room temperature radiation detectors. In this paper, the effects of different electrode structures on the performance of CdMgTe detectors were studied. The electrodes were prepared by vacuum evaporation and chemical precipitation method using Au and Al materials. The results indicated that CdMgTe detectors with Au/CdMgTe/Al electrode structure prepared by vacuum evaporation method had the best electrical properties. For the crystals grown by Cd-excess and Te-rich conditions, the resistivity were 2.89 × 1011 Ω cm and 3.8 × 1011 Ω cm, the leakage current (under 100 V bias voltage) were 4 nA and 3 nA, and the Hall mobility were 2.73 × 103 cm2 V−1 s−1 and 3.69 × 102 cm2 V−1 s−1, respectively. The conductive type of the crystals were weak n-type. 241Am @ 5.48 MeV α particle spectra of the detectors showed that the optimal energy resolution were 8.66% and 8.62%, and the carrier mobility-lifetime products (μτ)e were 1.47 × 10−3 cm2/V and 1.03 × 10−3 cm2/V, respectively. Moreover, the carrier mobility obtained by time-of-flight (TOF) test were 15.01 cm2/(V·s) and 77.79 cm2/(V·s), respectively.