Enhancement of Light Extraction Efficiency for InGaN/GaN Light-Emitting Diodes Using Silver Nanoparticle Embedded ZnO Thin Films

Abstract

In this study, we propose a liquid-phase-deposited silver nanoparticle embedded ZnO (LPD-Ag NP/ZnO) thin film at room temperature to improve the light extraction efficiency (LEE) for InGaN/GaN light-emitting diodes (LEDs). The treatment solution for the deposition of the LPD-Ag/NP ZnO thin film comprised a ZnO-powder-saturated HCl and a silver nitrate (AgNO3) aqueous solution. The enhanced LEE of an InGaN/GaN LED with the LPD-Ag NP/ZnO window layer can be attributed to the surface texture and localized surface plasmon (LSP) coupling effect. The surface texture of the LPD-Ag/NP ZnO window layer relies on the AgNO3 concentration, which decides the root-mean-square (RMS) roughness of the thin film. The LSP resonance or extinction wavelength also depends on the concentration of AgNO3, which determines the Ag NP size and content of Ag atoms in the LPD-Ag NP/ZnO thin film. The AgNO3 concentration for the optimal LEE of an InGaN/GaN LED with an LPD-Ag NP/ZnO window layer occurs at 0.05 M, which demonstrates an increased light output intensity that is approximately 1.52 times that of a conventional InGaN/GaN LED under a 20-mA driving current.

Surface/Interface Engineering for Constructing Advanced Nanostructured Light-Emitting Diodes with Improved Performance: A Brief Review

“…Once the internal TIR is reduced and the light radiation propagation is improved, surface texturing techniques can be used to further improve the light extraction efficiency [108]. Recently, Lei et al used the surface texture and LSP coupling effect to enhance the light extraction efficiency for InGaN/GaN LEDs [113].…”

“…All the results show that the surface-sensitive characterization is expected to help to reveal the role that the interface plays in various devices and to identify specific strategies to regulate and tune the properties of the surface/interface, leading to enhanced device performance. For the 2D materials, core-shell, 3D pixel configuration, back-end-of-line material, and device structures are designed to optimize the device performance [107][108][109][110][111][112][113]. For example, Zhang et al insert a 4-nm Si3N4 layer between the ZnSe core and the CdS shell of p-ZnSe/n-CdS core-shell heterojunctions to passivate the interface defects and reduce the recombination and the saturation current [107].…”

Lattice Constant Effect on Diffracted Transmission of ITO Periodic Nanostructures and Improvement of the Light Extraction Efficiency of Light-Emitting Diodes

“…To date, light emitting diodes (LEDs) have been widely utilized as energy-saving and environment-friendly light sources [1][2][3][4][5]. Research is ongoing to improve LED performance through more efficient light-generating and light-extracting structures [6,7]. However, owing to the large difference in the refractive indices between the semiconductor materials and the air, conventional LEDs still suffer from limited light extraction [8][9][10][11].…”

Self-Aligned Hierarchical ZnO Nanorod/NiO Nanosheet Arrays for High Photon Extraction Efficiency of GaN-Based Photonic Emitter

“…For achieving a higher photon extraction efficiency (PEE), a material with a refractive index lower than that of ITO (2.1 at visible wavelengths) is required to reduce the total internal reflection (TIR) in a conventional photonic emitter (C-emitter) and increase its outward light emission, that is, in air (n = 1). Although the ZnO nanostructures can partially mitigate the abrupt change of refractive indices between p-type GaN and air, TIR and Fresnel reflection losses occur at the ZnO/air interface [19,20].…”