Multilevel, solar-blind, and thermostable physical unclonable functions based on host-sensitized luminescence of β-Ga2O3:Dy3+ †

Abstract

Optical physical unclonable functions (PUFs) are powerful tools to combat counterfeiting, owing to their unpredictable preparation processes and unique, identifiable information content. Achieving high entropy and robustness in optical PUFs is essential for practical applications but remains challenging. This study demonstrates a multilevel, solar-blind, and thermostable PUF based on host-sensitized luminescence of trivalent dysprosium (Dy³⁺) in β-phase gallium oxide (β-Ga₂O₃). The controllable occupation of Dy³⁺ in both tetrahedral and octahedral Ga³⁺ sites of β-Ga₂O₃ results in heterochromatic optical emission, which affords the resulting PUFs with a multilevel encoding capacity of 4⁴⁰⁹⁶ at 64 × 64 pixels. The wide bandgap (∼4.6 eV) of β-Ga₂O₃:Dy³⁺ confines the PUF response to solar-blind irradiation, encompassing a light spectrum in the range 230–270 nm, which does not overlap with ambient light, ensuring interference-free stimulation and therefore achieving 100% recognition accuracy. Additionally, the high thermal quenching activation energy (0.386 eV) of β-Ga₂O₃:Dy³⁺ provides thermal stability, enabling the PUFs to operate from room temperature up to 125 °C. With near-ideal uniformity, uniqueness, and reproducibility, these PUFs hold considerable promise for practical applications in anticounterfeiting and encryption.