Solar-blind ultraviolet β -Ga2O3 phototransistor for logic and secure optical communication applications

This work presents the fabrication of a high-performance solar-blind phototransistor based on a β-Ga2O3 thin film with a ring-shaped gate electrode, featuring a high-κ Al2O3 gate dielectric layer. Under 255 nm ultraviolet (UV) illumination, the device exhibits a high specific detectivity (D*) of 5.26 × 1014 Jones, a photo-to-dark current ratio of 7.11 × 105, a responsivity (R) of 4.01 A/W, and a UV-to-visible rejection ratio of 6 × 102. In addition, by using the gate voltage and solar-blind UV light as inputs and adjusting the source–drain voltage, switchable Not OR and Not AND (NAND) logic functions are achieved, with the source–drain current as the output. Based on the NAND logic operation, the gate voltage serves as a key to encrypt input signals, enabling secure optical communication. These results provide an appropriate approach for implementing secure optical communication based on Ga2O3 phototransistors.