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 the 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 under 40 keV X-rays. 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.