Abstract
We report on an integrated plasmonic ultraviolet (UV) photodetector composed of aluminum Fano-resonant heptamer nanoantennas deposited on a Gallium Nitride (GaN) active layer which is grown on a sapphire substrate to generate significant photocurrent via formation of hot electrons by nanoclusters upon the decay of nonequilibrium plasmons. Using the plasmon hybridization theory and finite-difference time-domain (FDTD) method, it is shown that the generation of hot carriers by metallic clusters illuminated by UV beam leads to a large photocurrent. The induced Fano resonance (FR) minimum across the UV spectrum allows for noticeable enhancement in the absorption of optical power yielding a plasmonic UV photodetector with a high responsivity. It is also shown that varying the thickness of the oxide layer (Al2O3) around the nanodisks (tox) in a heptamer assembly adjusted the generated photocurrent and responsivity. The proposed plasmonic structure opens new horizons for designing and fabricating efficient opto-electronics devices with high gain and responsivity.
Highlights
In recent years, there has been growing interest for plasmonic photodetectors for a wide spectral range covering terahertz (THz) to visible frequencies [1,2,3]
We propose a novel device based on plasmonic Al/Al2O3 nanoparticle assemblies integrated into a Gallium Nitride (GaN) UV photodetector
A method is proposed to enhance the photoresponse of a GaN UV detector using plasmon hybridization mechanism
Summary
There has been growing interest for plasmonic photodetectors for a wide spectral range covering terahertz (THz) to visible frequencies [1,2,3] In all these works, several strategies have been used to enhance the absorption, responsivity, and quantum efficiency of the photodetectors. In spite of the extensive researches, the UV photodetectors suffer from dissipative losses, large dark currents, limited responsivity and quantum efficiency [10,11] To address these challenges and improve the performance of the UV detectors, two major methods have been proposed: (1) Avalanche multiplication [12], and (2) photoconductive gain [13]. Aluminum has widely been employed in designing light harvesting devices, nanoantennas, cathodoluminescence spectroscopy, and antireflective surfaces [18,19,20,21], in spite of the inherent and rapid oxidation
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