Fabrication and improvement of nanopillar InGaN / GaN light-emitting diodes using nanosphere lithography

Abstract

Abstract. Surface-patterning technologies have enabled the improvement of currently existing light-emitting diodes (LEDs) and can be used to overcome the issue of low quantum efficiency of green GaN-based LEDs. We have applied nanosphere lithography to fabricate nanopillars on InGaN∕GaN quantum-well LEDs. By etching through the active region, it is possible to improve both the light extraction efficiency and, in addition, the internal quantum efficiency through the effects of lattice strain relaxation. Nanopillars of different sizes are fabricated and analyzed using Raman spectroscopy. We have shown that nanopillar LEDs can be significantly improved by applying a combination of ion-damage curing techniques, including thermal and acidic treatment, and have analyzed their effects using x-ray photoelectron spectroscopy.

Size-controlled InGaN/GaN nanorod LEDs with an ITO/graphene transparent layer

“…The other method is a top-down process. Nanostructure can be formed by the top-down etching of the LED epitaxial layer using a nanoscaled etch mask such as metal nanoparticles, silica nanosphere, and a photoresist (PR) mask patterned by nano-imprint or hologram lithography [10][11][12]. The latter approach is relatively easy to realize the nanostructured LEDs and is suitable for mass production, because the optimized growth condition of the planar LED epitaxial layer is generally well known.…”

Enabling Localized Surface Plasmon Emission from InGaN/GaN Nano-LEDs Integrated with Ag/SiO2 Nanoparticles

“…For improving the light extraction efficiency of nanorod LEDs, the study of the localized surface plasmon (LSP) effect is a topic of interest among several methods, such as physical surface passivation, chemical treatment, and strain relaxation. − The LSP coupling effect is recognized as a simple and effective approach to increase light extraction from nanorod LEDs. Here, free-electron oscillations occurring at the surface of metal nanoparticles (NPs) are responsible for the improvement in the light output of LEDs. − It is well-documented that strong LSP coupling is exerted between the active multiple quantum well (MQW) of LEDs and metal NPs with close proximity once the emission wavelength of LEDs matches the LSP resonance of metal NPs.…”

Comparative study on luminescence extraction strategies of LED by large-scale fabrication of nanopillar and nanohole structures

“…Many efforts have been made to improve the EXE of LEDs, among which nanostructure patterning is one of the most widely investigated and highly applicable techniques. Top down approaches were previously reported in the fabrication of nanopillar structures via nanosphere lithography [6,7], e-beam lithography [8,9] or nanoimprint technique [10,11]. These nanopillar LEDs are supposed to have two advantages in efficiency improvement due to: firstly, suppression of total-internal-reflection (TIR) compared to planar LEDs [12], and secondly, accommodation of the large lattice mismatch at heterointerface because of strain relief in nanopillars of a small diameter [13].…”