Abstract
In this work, flip-chip AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) with various meshed contact structures are systematically investigated via three-dimensional finite-difference time-domain (3D FDTD) method. It is observed that both transverse electric (TE)- and transverse magnetic (TM)-polarized light extraction efficiencies (LEEs) are sensitive to the spacing and inclined angle for the meshed structure. We also find that the LEE will not be increased when a large filling factor is adopted for the meshed structures, which is because of the competition among the p-GaN layer absorption, the Al metal plasmon resonant absorption, and the scattering effect by meshed structures. The very strong scattering effect occurring in the hybrid p-GaN nanorod/p-AlGaN truncated nanocone contacts can enormously enhance the LEE for both TE- and TM-polarized light, e.g., when the inclined angle is 30°, the LEE for the TE- and TM-polarized light can be increased by ~ 5 times and ~ 24 times at the emission wavelength of 280 nm, respectively.
Highlights
AlGaN-based deep ultraviolet light-emitting diodes (DUV Deep ultraviolet light-emitting diodes (LEDs)) have great application potentials in the scopes such as water purification, medical phototherapy, detection, and photocatalysis [1,2,3]
Effect of the Optical Cavity Thickness on light extraction efficiency (LEE) As it is well known, the optical cavity effect can tune the radiation mode for Multiple quantum wells (MQWs) in flip-chip LEDs, which is sensitive to the p-type layer thickness, while the p-type layer thickness has a significant influence on LEE [27]
It can be observed that the average LEE for transverse magnetic (TM)-polarized light is only one tenth of that for transverse electric (TE)-polarized light, and the findings here are consistent with the results in [23]
Summary
AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) have great application potentials in the scopes such as water purification, medical phototherapy, detection, and photocatalysis [1,2,3]. We find that the LED with optimized hybrid p-GaN nanorod/p-AlGaN truncated nanocone meshed contacts enables over 5-fold and 24-fold LEE enhancement for transverse electric (TE)and TM- polarized light, respectively.
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