Reconfiguring the Energy Relaxation Pathway via a Counterintuitive Defect Engineering for Synergistic Optimization of β ‐Ga 2 O 3 Scintillators

Scintillator development has long been constrained by the trade‐off between decay time and light yield. Here, we reported a counterintuitive defect engineering strategy that successfully reconciles these conflicting metrics in β ‐Ga 2 O 3 . Through controlled atmosphere annealing, a specific configuration of gallium vacancies (V Ga ) is intentionally introduced which function as relay levels for energy transfer, effectively redirecting carriers toward self‐trapped exciton (STE) luminescence channels. The optimized β ‐Ga 2 O 3 scintillator achieves a high light yield of 9647 ph/MeV, representing a 1.38‐fold enhancement over the unannealed crystal (6971 ph/MeV). Remarkably, this substantial improvement is attained while preserving the material's intrinsically ultrafast decay time (∼9.1 ns). Furthermore, the material demonstrates an outstanding spatial resolution of 19 lp mm −1 , nearly twice that of the commercial benchmark CsI:Tl scintillator (∼10 lp mm −1 ). This work not only overturns the traditional perception of defects merely as non‐radiative recombination centers but also establishes defect‐assisted luminescence as a design principle for synergistically boosting the light yield and speed of wide‐bandgap oxide scintillators.