Self-Powered Wavelength-Selective Ultraviolet Bipolar Photodetector Based on Al/p-GaN/In:Ga₂O₃/SnO₂ Structure for...

Area of Science:

• Optoelectronics
• Materials Science
• Information Security

Background:

• Free-space optical (FSO) communication offers high data rates but faces security challenges due to signal leakage.
• Solar-blind ultraviolet (UV) communication provides a high signal-to-noise ratio (SNR) advantage over visible and infrared (IR) bands.
• Exploration of novel cryptographic photodetectors for UV wavebands remains limited.

Purpose of the Study:

• To design and fabricate a self-powered UV photodetector for secure optical communication (SOC).
• To investigate the photodetector's wavelength-selective bipolar photoresponse.
• To demonstrate an encryption and decryption system utilizing the photodetector's unique properties.

Main Methods:

• Fabrication of a self-powered Al/p-GaN/In:Ga2O3/SnO2 UV photodetector.
• Characterization of the photodetector's photoresponse under different UV wavelengths (254 nm and 365 nm) at zero bias.
• Development and testing of a secure optical communication system using the photodetector for binary signal encryption and decryption.

Main Results:

• The photodetector exhibited a wavelength-selective bipolar photoresponse, with negative and positive photocurrents at 254 nm and 365 nm, respectively.
• High responsivities (-5 mA/W and 0.52 mA/W) and specific detectivities (-7.2 × 10^11 Jones and 7.47 × 10^10 Jones) were achieved at zero bias.
• Successful encrypted transmission and accurate decryption of the string "CUST" were demonstrated in the SOC system.

Conclusions:

• The developed photodetector offers a new strategy for high-performance, multifunctional bipolar UV photodetectors.
• The study presents an innovative pathway for next-generation, high-security, low-power optical communication systems.
• The synergistic regulation by heterojunction and Schottky junction is key to the device's performance.