Depletion Region in Cr/CdTe/Au Schottky Diode X- and $\gamma$ -Ray Detectors

Abstract

The electrical and spectral characteristics of the Cr/cadmium telluride (CdTe)/Au structures with a Schottky contact at the Cr–CdTe interface and near ohmic contact at the Au–CdTe interface were studied. The Schottky diodes were fabricated using high-resistivity CdTe(111) single-crystal wafers with different thicknesses (0.5–2 mm) after preliminary chemical etching and also additional surface treatment by Ar-ion bombardment was employed. Electronic parameters such as the concentration of uncompensated impurities, width of the space-charge region, and the thickness of the depletion region were calculated based on the comparison of the voltage dependences of the photopeak heights in the 241Am isotope spectra excited from the Schottky contact side and ohmic contact side, respectively. The obtained Cr/CdTe/Au Schottky diodes with low leakage current [a few nanoampere (nA) at 1000–1500 V] show promise as high-energy resolution spectroscopic X-/gamma ( $\gamma $ )-ray detectors.