Light-extraction enhancement in GaN-based light-emitting diodes using grade-refractive-index amorphous titanium oxide films with porous structures

Abstract

Amorphous titanium oxide (a-TiOx:OH) films prepared by plasma-enhanced chemical-vapor deposition at 200 and 25 °C are in turn deposited onto the GaN-based light-emitting diode (LED) to enhance the associated light extraction efficiency. The refractive index, porosity, and photocatalytic effect of the deposited films are correlated strongly with the deposition temperatures. The efficiency is enhanced by a factor of ∼1.31 over that of the uncoated LEDs and exhibited an excellent photocatalytic property after an external UV light irradiation. The increase in the light extraction is related to the reduction in the Fresnel transmission loss and the enhancement of the light scattering into the escape cone by using the graded-refractive-index a-TiOx:OH film with porous structures.

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO2 Nanocomposite Structure

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“…In recent decades, the photocatalytic degradation of organic and inorganic pollutants using oxide semiconductor-based materials had been extensively studied [ 1 , 2 , 3 , 4 , 5 ]. Among these materials, titanium dioxide (TiO 2 ) has been the most popular candidate due to its chemical stability, optical transparency at visible wavelength, high refractive index, non-toxic nature, and low cost [ 6 , 7 , 8 ]. Engineers have demonstrated that the TiO 2 material with the anatase structure has the best photocatalytic activity [ 9 , 10 ].…”

Enhancement of light extraction efficiency in InGaN/GaN vertical blue light emitting diodes by surface patterning: Design and simulation

“…Various methods have been projected to improve the light extraction efficiency of LEDs such as micro-patterning [5,6], nanopatterning [7], micro-cavity LED design [8], surface roughing [9,10], coating of porous films [11], photonic crystals [12], and many more. Patterning the surface is one of the most efficient ways to improve the light output power because of multiple chances of light escape from the surface.…”

Improvement of GaN light-emitting diodes with surface-treated Al-doped ZnO transparent Ohmic contacts by holographic photonic crystal

“…Recently, high-efficiency GaN-based light-emitting diodes (LEDs) attracted considerable interest due to their potential applications in optoelectronic devices such as traffic signals, full-color displays, and high efficiency lamps [1][2][3][4]. Improved LED performances through enhanced light extraction have been reported and commercialized using transparent conducting oxide (TCO) contacts with optical output comparable or superior to conventional LED [5,6], such as impurity doped SnO 2 , In 2 O 3 , and ZnO, etc.…”