Individual Roles of Atoms and Ions during Hydrogen Plasma Passivation of Surface Defects on GaN Created by Plasma Etching

We investigated the effect of the sidewall passivation by hydrogen plasma on the InGaN green micro-LED performance. Hydrogen passivation deactivates the surface region of p-GaN around the perimeter of the device mesa. Thus, hole injection is suppressed in this region, where etching-caused material degradation results in leakage current, decreasing device efficiency. We have confirmed the hydrogen passivation effect on LED square pixels with sizes of 20 µm and 100 µm. For smaller LEDs, the reverse leakage current has reduced more than tenfold, and the external quantum efficiency of LEDs was enhanced 1.4-times due to the suppression of the non-radiative recombination.

mentioning

confidence: 99%

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

Kirilenko¹,

Iida²,

Zhuang³

et al. 2022

“…On the other hand, it is reported that Ga droplets are produced by heating in a hydrogen atmosphere 24) or Ar/N 2 plasma treatment, 25) and that nitrogen is desorbed in hydrogen plasma treatment. 26) It is also reported that H 2 plasma treatment of a SnO 2 substrate produces spherical Sn droplets on the surface. 27,28) Therefore, there is a possibility that the Ga droplets shown in Fig.…”

mentioning

confidence: 95%

High-speed etching of gallium nitride substrate using hydrogen-contained atmospheric-pressure plasma

Sano

Nakaue

Toh

et al. 2023

Atmospheric-pressure plasma etching of gallium nitride (GaN) substrate using hydrogen radicals instead of chlorine radicals was investigated toward the backside thinning of GaN vertical power devices to reduce on-resistance. As a basic experiment, a pipe-shaped electrode was placed facing the GaN substrate to generate atmospheric-pressure plasma of a gas mixture of helium and hydrogen, and high-speed etching of approximately 4 μm/min was achieved. Although many spherical Ga metal particles were observed on the surface after processing, the addition of oxygen gas was found to be able to suppress them.

“…[7][8][9][10][11] Thus, to ensure excellent material properties and provide high-performance devices, it is strongly required that the damage induced by plasma etching should be reduced or prevented. [12][13][14] Thermal annealing of GaN has been investigated for the recovery or improvement of the optical and electrical performance, and many researchers have reported that thermal annealing can recover the original material properties after process-induced damage. [15][16][17] However, if Ga-N bonds are broken during plasma etching processes at room temperature, then nitrogen is preferentially lost due to its high vapor pressure, which results in a gallium-rich surface.…”

mentioning

confidence: 99%

A High-Temperature Nitrogen Plasma Etching for Preserving Smooth and Stoichiometric GaN Surface

Kometani

Ishikawa

Takeda

et al. 2013

Self Cite

We report the damageless surface morphology of gallium nitride (GaN) films during argon and nitrogen plasma etching at elevated temperatures up to 600 °C. For Ar plasma bombardment at high substrate temperatures of around 600 °C, Ar+ ion bombardment dissociates Ga–N bonds by the preferential removal of nitrogen, which promotes roughness of the GaN surface by the aggregation of gallium atoms. For the N2 plasma one, the N/Ga remains stoichiometric with higher values above 0.69, and the surface is not significantly roughened, even at 600 °C. Therefore, the aggregation of metallic Ga induces surface roughening during ion-enhanced etching of GaN at elevated substrate temperatures.