Low damage dry etch for III-nitride light emitters

Abstract

We have developed a dry etch process for the fabrication of lithographically defined features close to light emitting layers in the III-nitride material system. The dry etch was tested for its effect on the internal quantum efficiency of c-plane InGaN quantum wells using the photoluminescence of a test structure with two active regions. No change was observed in the internal quantum efficiency of the test active region when the etched surface was greater than 71 nm away. To demonstrate the application of the developed dry etch process, surface-etched air gaps were fabricated 275 nm away from the active region of an m-plane InGaN/GaN laser diode and served as the waveguide upper cladding. Electrically injected lasing was observed without the need for regrowth or recovery anneals. This dry etch opens up a new design tool that can be utilized in the next generation of GaN light emitters.

Comparative study on luminescence extraction strategies of LED by large-scale fabrication of nanopillar and nanohole structures

“…Nanopillar and nanohole designs have shown advantages in optical coupling, but sub-surface damages induced by dry etching is inevitable, which deteriorates device performance by the introduction of defects and amorphous layers [25,26]. These RIE-induced defects are likely to form non-radiative recombination sites that decrease the luminescence efficiency [30]. Therefore, it is imperative to recover the etch damages without sacrificing the merit of light scattering effect by PhC.…”

A review on the low external quantum efficiency and the remedies for GaN-based micro-LEDs

“…A proposed method is making the chemical sidewall treatment in the potassium hydroxide (KOH) or ammonium sulfide for e.g. traditional LEDs and mini-LEDs [80,[82][83][84]. Measurement shows that the wetetching can produce faceted and extremely smooth sidewalls [85].…”

53.2: Fabrication and Characterization of InGaN‐GaN MQWs Micro‐LEDs with Optimized Morphology and array structure

“…With previous academic investigation from scientist, we know that the plasma generated in the ICP etching or PECVD process will damage the sidewall of the GaN devices (3,4), which will weaken the luminous efficiency of the LED device. During our fabrication process, we changed the power of etching process to obtain different sidewall morphology of mesa, while high power may cause more folds on the sidewall, and low power may be smoother but a little residue under the wall.…”