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

Abstract

A GaN-based light-emitting diode (LED) grown on a nanocomb-shaped patterned sapphire substrate (PSS) is fabricated and studied. Nanocomb-shaped patterns are transferred on a sapphire substrate using a well-ordered anodized aluminum oxide (AAO) thin film as a mask for the inductively coupled plasma etching process. This well-ordered AAO thin film with a high aspect ratio is grown on a sapphire substrate by an oxalic acid-based electrochemical system and a threestep anodization. The strain state generated during epitaxial growth could be effectively alleviated by the use of nanocombshaped PSS. The treading dislocation density could be reduced. Thus, the enhanced crystalline quality is obtained. In addition, due to the presence of photonic crystal-like air buffer layer, part of reflected photons upward the top side could be scattered by this layer. Therefore, more photons could be extracted outside. Experimentally, at 20 mA, as compared with a conventional LED grown on a planar sapphire substrate, the studied LED grown on a nanocomb-shaped PSS shows 53.8% and 43.7% enhancements in light output power and external quantum efficiency as well as a reduced leakage current.

Fabrication and Characterization of Nanonet-Channel LTPS TFTs Using a Nanosphere-Assisted Patterning Technique

“…Here, a nanosphere-assisted patterning (NAP) technique involving oxygen plasma treatment has been developed to form the nanonet structure. The NAP technique with the advantages of inexpensive equipment and the capability of large-area patterning, has been widely used to realize periodic photonic devices [ 23 , 24 ], solar cell [ 25 ], biological devices [ 26 , 27 ], and electrical sensors [ 28 , 29 ].…”

Light Extraction Enhancement of InGaN Based Micro Light-Emitting Diodes with Concave-Convex Circular Composite Structure Sidewall

“…To this end, the photon escaped from the gallium nitride (GaN) sidewall can be increased by reducing the TIR, thereby realizing the improvement of light extraction efficiency (LEE) and light efficiency [14][15][16]. Several advantageous approaches have been put forward to increase the LEE, such as patterned sapphire substrates [17][18][19], textured surfaces [19][20][21][22], SiO 2 MS/MP [9,23,24], composite transparent conductive layer [5,25], microlens array [26,27], and photon crystals [16,28,29]. Meanwhile, the LEE can be improved by roughening the bottom [30] or sidewalls of the LED.…”