Enhancement of the light output of GaN-based ultraviolet light-emitting diodes by a one-dimensional nanopatterning process

Abstract

We have demonstrated the enhancement of the output power of ultraviolet GaN-based light-emitting diodes ͑LEDs͒ by using one-dimensionally nanopatterned Cu-doped indium oxide͑CIO͒/indium tin oxide ͑ITO͒ p-type contact layers. The one-dimensional ͑1D͒ nanopatterns ͑250 nm in width and 100 nm in depth͒ are defined using a TiO 2 1D nanomask fabricated by means of a surface relief grating technique. When fabricated with the nanopatterned p-contact layers, the output power of LEDs is improved by 40 and 63% at 20 mA as compared to those fabricated with the unpatterned CIO/ITO and conventional Ni/ Au contacts, respectively.

First principles study on the properties of p-type conducting In:SnO2

“…Tin-doped indium oxide (In 2 O 3 :Sn) or ITO, as a typical transparent conducting oxide (TCO), has received extensive studies for its use in applications such as flat panel displays and solar cells [1][2][3]. In preparing TCOs, In 2 O 3 is always treated as a substrate material, while Sn is considered an adjusting element to obtain low resistivity (b200 μΩ cm) and high transmittance (N90%) in the visible light range of the spectrum [4,5].…”

Enhancement of the light output of GaN-based light-emitting diodes with surface-patterned ITO electrodes by maskless wet-etching

“…In order to enhance light extraction efficiency, various methods, such as photonic crystals [1], GaN surface roughening [2], and patterned sapphire substrates [3], have been used. In addition, the surface texturing [4,5] and the patterning [6,7] of transparent p-type electrodes have been also introduced and shown to be effective for improving LED efficiency. For example, Horng et al reported that the output power of LEDs could be enhanced (by 28%) through the use of textured ITO window layers formed by a natural lithography technique [5].…”

Development of a cost effective surface-patterned transparent conductive coating as top-contact of light emitting diodes

“…A transparent polymer can be affixed over the device to create a larger escape angle to air. 8 Another way to improve light output is to roughen or to pattern transmission grating 5,[9][10][11][12][13] on the emission surface that offers the trapped light more angles of escape. Grating structures of various shapes like pyramidal, spherical, conical, sinusoidal, cylindrical, and so on can be studied, but only a few can be fabricated with great success.…”