Effect of low-temperature rapid annealing on structural and electrical properties of electroless platinum contacts on CdZnTe detectors

In this work, platinum (Pt) electrodes were deposited on CdZnTe wafers by electroless H2PtCl4 solution and subsequently annealed at different temperature from 323 K to 473 K. Focused ion beam (FIB) imaging, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), current-voltage (I–V) analysis and energy spectra under 241Am irradiation were adopted to investigate the effect of low-temperature rapid annealing on interface structure, electrical and carrier transport properties of Pt/CdZnTe samples. Single-crystal PtTe layer with [100] orientation and thickness of 20 nm was found in the interface between electroless Pt and CdZnTe wafer. The leakage current of the Pt/CdZnTe detectors at 200 V decreased from 212 nA cm−2 to 101 nA cm−2 after low-temperature rapid annealing, due to a decrease of voltage drop across the PtTe interface layer. The energy spectra and carrier transport performance of Pt/CdZnTe detectors suggested that the optimal annealing temperature was 423 K. The energy spectra of Pt/CdZnTe detector under 241Am showed that the FWHM was improved from 23.3% to 14.4%, while the full charge collection and mobility lifetime product of electrons increasing from 611 to 625 and 3.17 × 10−3 to 3.76 × 10−3 cm2 V−1 s−1, respectively.