Bi-activated MgGa2O4 phosphors with rich defect energy levels: Spectral property and optical storage applications

Optical high-density information storage can meet explosive increase in significant data demand. Electron-capture materials are very promising for optical information storage. The trap density and depth of the material limit their storage density and information retention. This work successfully prepared a novel material with abundant trap energy levels by selective Bi3+ doping into the MgGa2O4 host (MgGa2O4:Bi3+). A combinatorial synthesizer screened the optimal Bi doping ratio. The optical storage mechanism was systematically analyzed based on the energy band structure combined with theoretical calculations. The internal trap properties of MgGa2O4:Bi3+ were studied in detail using photoluminescence spectroscopy, X-ray photoelectron spectroscopy, electron spin resonance, etc. Ascribed to the high density of defects with Bi doping, the existence of multiple continuously distributed trap levels in MgGa2O4:Bi3+ could be verified, where deep traps are essential for information storage. Not only the capability of optical storage was characterized by the visualization method, and the {10 × 10} information points were encoded/decoded by femtosecond laser on the surface of the simulated disk. The information conversion between binary 0 and 1 was successfully achieved, making it an excellent optical storage medium for the future.