Diffusion induced high Al content β-(AlxGa1-x)2O3 toward multiple wavelengths deep-ultraviolet photodiodes

We report high Al content single-phase β-(Al x Ga 1-x ) 2 O 3 achieving 900 nm thickness on 2-in. c-plane sapphire substrates through diffusion process from 1100 to1350°C. Thermal driven cation exchange allows continuous compositional modulation and realises a maximum surface Al fraction of 60%. As synthesized β-(Al x Ga 1-x ) 2 O 3 feature homogeneous in-plane Ga and Al distribution and an upward Al gradient toward the substrate, accompanied by bandgap widening over 5.85 ± 0.05 eV. The MSM deep-UV photodetectors exhibit wavelength tunable responsivities of 0.116 A/W at 216 nm, 0.083 A/W at 215 nm, and 0.0181 A/W at 210 nm, respectively. Although Photodetection degrades with elevated temperature, the diffusion process serves as a scalable strategy for synthesizing high Al content β-(Al x Ga 1-x ) 2 O 3 toward multiwavelength deep-UV detection.