Balance of charge carrier mobility-lifetime and resistivity for enhancing X-ray detection sensitivity in Sn: Ga2TeO6 crystal

High-performance direct X-ray detectors are critical in various fields such as medical radiography, security checks, and so on. However, due to ultrahigh resistivity, most of the oxide crystals used in X-ray detection are still challenging. In this paper, ion doping in semiconductors is considered to be an effective strategy to balance the X-ray detection sensitivity and detection limit. Here, both Ga₂TeO₆ and Sn: Ga₂TeO₆ crystals are rationally designed and successfully grown by the top-seeded solution growth (TSSG) technique. Along the a- and c-axes, the resistivities and carrier mobility lifetimes (μτ) products of Ga₂TeO₆ crystal are determined to be 2.93 × 10¹³ Ω cm and 5.44 × 10⁻⁴ cm² V⁻¹, and 2.65 × 10¹³ Ω cm and 6.93 × 10⁻⁴ cm² V⁻¹, respectively. The Ga₂TeO₆ crystal-based X-ray detectors show the detection sensitivities of 220 μC Gy_air⁻¹ cm⁻² and 253 μC Gy_air⁻¹ cm⁻² and low detection limits of 12.1 nGy_air s⁻¹ and 48.9 nGy_air s⁻¹, respectively. Due to efficient doping, the resistivity and μτ product in Sn: Ga₂TeO₆ along the c-axis are optimized to 9.51 × 10¹² Ω cm and 1.76 × 10⁻³ cm² V⁻¹. Thus, the sensitivity of Sn: Ga₂TeO₆ is enhanced to 575 μC Gy_air⁻¹ cm⁻², which is two times that of Ga₂TeO₆ crystal, and the detection limit is determined to be 97.0 nGy_air s⁻¹. This work provides a new X-ray detection material and proposes an efficient strategy to enhance the X-ray detection sensitivity of materials, especially for high-resistivity crystals.