Inductively coupled plasma etching of nano-patterned sapphire for flip-chip GaN light emitting diode applications

Abstract

The flip-chip configuration is employed for the production of high-brightness GaN-based light emitting diodes to improve the extraction of heat. A lithographic approach based on a sacrificial SiO 2 nanosphere etch mask was developed to enhance the external extraction of light from the sapphire substrate. Closed-packed arrays of SiO 2 nanospheres were prepared by a simple solution-based method on the sapphire substrate. Subsequent dry-etching via inductively coupled plasma using a gas mixture of BCl 3 and Cl 2 transferred a pattern into the sapphire substrate with the lowest etching at the center of the SiO 2 nanosphere. This process created an array of circular cones in the surface of the sapphire that were found to be effective in enhancing the light extraction efficiency through multi-photon scatterings. Room temperature photoluminescence exhibited an increase of 22.5% in intensity after the surface of sapphire was textured.

Inkjet-printed silver film on multilayer liquid crystal polymer for fabricating a miniature stub-loaded bandpass filter

“…Emerging system-in-package and three-dimensional (3D) integration technologies [1][2][3][4] are the predominant providers of solutions for miniaturizing systemized radio frequency or millimeter wave devices. Previous research [5] reported the development of an inkjet-printed folded-bowtie radio frequency identification tag module on a paper substrate.…”

Gallium nitride light emitter on a patterned sapphire substrate for improved defectivity and light extraction efficiency

“…Unfortunately, the dimensions of a photonic crystal designed for a GaN-based emitter are on the order of 250 nm [5], which is difficult to implement in a highvolume lithography process e although self-assembled approaches have proven promising [6]. A much simpler manufacturing approach is to roughen the GaN surface or the sapphire substrate (in a flip-chip configuration) to create an ensemble of sub-micron scattering sites [7]. A recent variant of this approach is to roughen the surface of the sapphire substrate prior to growth [8].…”

Output power enhancement of GaN-based flip-chip light-emitting diodes via conical structures generated by a monolayer of nanospheres

“…Many research teams have attempted to improve LEE by roughening LED, in which the method of wet etching, dry etching and haze film has generally been used. [7][8][9][10][11][12][13] The aforementioned studies successfully enhanced FC LED efficiency by roughening sapphires. However, in actual industrial productions, sapphire substrates of FC LED must be thinned to 150 µm before they can be made into a surface structure.…”