InGaN-Based Light-Emitting Diodes Fabricated on Nano Patterned Sapphire Substrates with Pillar Height of More than 600 nm by Nanoimprint Lithography

Abstract

GaN-based light-emitting diodes (LEDs) were fabricated on nano patterned sapphire substrates (nano-PSSs) by nanoimprint (NIP) lithography. A nano-PSS with a pillar height of more than 600 nm was achieved. The surface emission of the LEDs was strongly affected by pillar height, and the surface emission intensity was highest at a pillar height of 250 nm. In contrast, the external quantum efficiency of the LEDs on the nano-PSSs with diameters of 100 and 450 nm was approximately 30% higher than that on a flat sapphire substrate, which is similar to that on a conventional PSS.

Application of patterned sapphire substrate for III-nitride light-emitting diodes

“…12a). 146 It was found that pattern height affected the surface emission of LEDs and highest emission intensity was obtained at a pillar height of 250 nm. The utilization of such PSS improved LEE and efficiency droop of LEDs, indicating the advantage of PSS over FSS (Fig.…”

“…(b) EQEs of LED chips on nano-PSSs as a function of injection current. Reproduced with permission 146. Copyright 2013, Institute of Physics Publishing.…”

Nanoimprint technology for patterning functional materials and its applications

“…While the device performance is enhanced significantly by the patterned sapphire, the pattern shapes are still random. NIL can be applied to fabricate sapphire substrates with designed textures [55][56][57]. For example, with the same procedure in the conventional NIL, the patterns were first transferred by pressing a flexible polyvinylchloride (PVC) stamp into the UV curable resist along with UV light exposure [55].…”

“…The patterned sapphire can enhance the luminescence efficiency of LEDs [55,56]. For example, a GaN based LED on a nanometer-scaled patterned sapphire substrate exhibited a stronger and sharper photoluminescence (PL) emission peak than that of the unpatterned LED [55].…”

Implementation of a High-Performance GaN-Based Light-Emitting Diode Grown on a Nanocomb-Shaped Patterned Sapphire Substrate

“…Yet, only a few approaches have been applied to form nanoscale patterns, especially for the one with a well-ordered arrangement [8]. Due to high cost and low throughput of these complex nanofabrication approaches, nanoscale PSS could not be implemented in commercial products [12]. For this reason, a potentially alternative approach to form nanoscale pattern by the use of self-organized anodized aluminum oxide (AAO) film is studied.…”