Rhodium-embedded UV photodetectors based on localized surface plasmon resonance on AlN/GaN

Area of Science:

• Optoelectronics
• Nanotechnology
• Materials Science

Background:

• Metal-semiconductor-metal photodetectors are crucial for UV detection.
• Enhancing photodetector performance, particularly responsivity and dark current, remains a key research area.
• Localized surface plasmon resonance (LSPR) offers a pathway to boost optical properties.

Purpose of the Study:

• To investigate the effect of a large-scale, uniform rhodium nanoparticle array on the responsivity of AlGaN-based photodetectors.
• To utilize LSPR for enhancing UV detection capabilities.
• To explore the self-assembly of quasi-triangular rhodium nanoparticles for device integration.

Main Methods:

• Theoretical simulations were performed to predict plasmon resonance wavelengths and electromagnetic field distributions.
• A hexagonal close-packed structure of quasi-triangular rhodium nanoparticles was fabricated on an AlN/GaN substrate using self-assembly nanosphere technology.
• Characterization of the fabricated photodetectors was conducted to evaluate their performance metrics.

Main Results:

• The rhodium nanoparticle-embedded photodetector exhibited a significantly reduced dark current (7 × 10⁻¹⁴ A).
• Maximum responsivity was observed at a longer wavelength (approx. 310 nm) compared to devices without nanoparticles.
• An enhancement ratio of responsivity as high as 56 was achieved at 324 nm.
• A highly uniform, large-scale rhodium nanoparticle array was successfully implemented.

Conclusions:

• The integration of a uniform, large-scale rhodium nanoparticle array effectively enhances the performance of AlGaN-based photodetectors in the UV region.
• LSPR from the rhodium nanoparticles is the primary mechanism for the observed improvements in responsivity.
• The self-assembly method provides a viable route for fabricating high-performance plasmonic photodetectors.