Engineered for Sensitivity: Rare‐Earth‐Doped Gd ₃ Ga ₅ O ₁₂ Crystals for Stable and High‐Performance X‐Ray Detection

Highly sensitive X‐ray detectors with low detection limits are essential for advancements in medical diagnosis, industrial inspection, and scientific research. In this paper, X‐ray detectors based on neodymium‐doped gadolinium gallium garnet (Nd: GGG) and thulium‐doped gadolinium gallium garnet (Tm: GGG) single crystals were fabricated. Both Nd: GGG and Tm: GGG single crystals demonstrate high crystal quality, a wide bandgap, and good operational stability and reliability. Electrical characterization shows that Tm: GGG possesses a higher room‐temperature bulk resistivity (6.35 × 10 13 Ω cm) and a larger carrier mobility‐lifetime product ( µτ = 4.17 × 10 −4 cm 2 V −1 ). Accordingly, the Au/Tm: GGG/Au detector achieves a high sensitivity of 393.45 µC Gy air −1 cm −2 and a low detection limit of 3.08 nGy air s −1 at 40 keV, with good operational stability. These results suggest the potential of Tm: GGG for high‐sensitivity, low‐dose X‐ray detection with a reasonable response, providing guidance for the optimization of rare‐earth‐doped GGG semiconductors in X‐ray detection applications.