Ion Migration Suppression in Quasi-2D CdTeMoO6 Crystals for High-Performance X-ray Detection

Abstract

Low and stable dark currents are critical in detection applications to improve detector sensitivity and signal-to-noise ratio. In this paper, the oxide crystal CdTeMoO₆ (CdTM) with a van der Waals layered structure shows potential as an X-ray detection material. The resistivity of CdTM single crystal (SC) along the layer direction is determined to be 3.21×10¹⁴ Ω cm, resulting in a low dark current of 0.6 pA at 333 V mm^-1. The carrier mobility lifetime product (μτ) is 4.79×10^-4 cm² V^-1, the recorded value of oxide SCs, and comparable to many perovskite SCs. The detection limit is 22 nGy_air s^-1, and the sensitivity reaches 455 μC Gy_air^-1 cm^-2 at 40 keV X-ray. By blocking the ion migration path through the unique quasi-two-dimensional (quasi-2D) layered structure, the ion migration can be effectively inhibited even at 333 V mm^-1. In addition, the unique lamellar growth habit of van der Waals layered CdTM crystals shows excellent prospects for large-area CdTM SCs for X-ray imaging. This work demonstrates that quasi-2D oxide SCs are poised to be utilized in X-ray detection, paving the way for X-ray imaging and expanding the X-ray material system.