Nanopillar Light-emitting Diodes Research Articles

Energy coupling processes in InGaN/GaN nanopillar light emitting diodes embedded with Ag and Ag/SiO2 nanoparticles

We synthesized Ag and Ag/SiO2 nanoparticles (NPs) and investigated the energy coupling processes between the localized surface plasmons of NPs and the active quantum well regions of nanopillar light-emitting diodes (LEDs). Nanopillar LEDs embedded with Ag NPs exhibited a decreased photoluminescence (PL) intensity, while the PL was markedly enhanced for Ag/SiO2 NP embedded nanopillar LEDs. Though the PL decay times decreased in both cases compared to the sample without NPs, the difference in observed optical behavior suggests that different types of energy coupling (EC) are involved.

Nanopillar InGaN/GaN light emitting diodes integrated with homogeneous multilayer graphene electrodes

InGaN/GaN nanopillar light-emitting diodes (LEDs) were fabricated using a highly homogeneous multilayer graphene (h-MLG) electrode. Four layers of h-MLG were prepared homogeneously using chemical vapor deposition and layer-by-layer transfer methods. The h-MLG exhibited excellent optical, structural and electrical properties for use as an electrode in the LEDs. The h-MLG was applied as a transparent top electrode by suspending only on the tip of nanopillar LEDs. The current-driven InGaN/GaN nanopillar LED with the h-MLG electrode was successfully operated at a high current injection and exhibited bright electroluminescence.

The fabrication of GaN-based nanopillar light-emitting diodes

InGaN/GaN multiple quantum well-based light-emitting diode (LED) nanopillar arrays were fabricated using Ni self-assembled nanodots as etching mask. The Ni nanodots were fabricated with a density of 6×108–1.5×109 cm−2 and a dimension of 100–250 nm with varying Ni thickness and annealing duration time. Then LED nanopillar arrays with diameter of approximately 250 nm and height of 700 nm were fabricated by inductively coupled plasma etching. In comparison to the as-grown LED sample an enhancement by a factor of four of photoluminescence (PL) intensity is achieved for the nanopillars and a blueshift as well as a decrease in full width at half maximum of the PL peak are also observed. The method of additional chemical etching was used to remove the etching-induced damage. Then nano-LED devices were further completed using a planarization approach to deposit p-type electrode on the tips of nanopillars. The current-voltage curves of both nanopillars and planar LED devices are measured for comparison.

Fabrication and Optical Characterization of GaN-Based Nanopillar Light Emitting Diodes

InGaN/GaN-multiple-quantum-well-based light emitting diode (LED) nanopillar arrays with a diameter of approximately 200 nm and a height of 700 nm are fabricated by inductively coupled plasma etching using Ni self-assembled nanodots as etching mask. In comparison to the as-grown LED sample an enhancement by a factor of four of photoluminescence (PL) intensity is achieved after the fabrication of nanopillars, and a blue shift and a decrease of full width at half maximum of the PL peak are observed. The method of additional wet etching with different chemical solutions is used to remove the etch-induced damage. The result shows that the dilute HCl (HCl:H2O=1:1) treatment is the most effective. The PL intensity of nanopillar LEDs after such a treatment is about 3.5 times stronger than that before treatment.