Atomic-scale and Damage-free Smoothing of $\boldsymbol{\beta-\text{Ga}_{2}\mathrm{O}_{3}}$ via Plasma-induced Atom Migration Manufacturing (PAMM)

$\boldsymbol{\beta-\text{Ga}_{2}\mathrm{O}_{3}}$
is an emerging next-generation ultra-wide bandgap semiconductor that shows great application potentials in high-power, high-frequency, and high-temperature electronic devices. However, its atomic-scale smoothing is a troublesome issue due to the natural difficult-to-machine feature. Herein, we proposed a damage-free technique to achieve the atomic-scale smoothing of
$\boldsymbol{\beta-\text{Ga}_{2}\mathrm{O}_{3}}$
using atmospheric pressure inductively coupled plasma (ICP). It is found that the high-temperature pure Ar ICP can impel surface atoms to migrate on
$\boldsymbol{\beta-\text{Ga}_{2}\mathrm{O}_{3}}$
, thus leading to the formation of atomically smooth surface following the decrease of surface energy, which is called plasma-induced atom migration manufacturing (PAMM). After the treatment at 900 W for 40 min, the Sa surface roughness dramatically decreases from 15.3 nm to 0.43 nm, and atomic-scale step-terrace structures can be observed on the atomically smooth substrate. Additionally, the crystal quality of
$\boldsymbol{\beta-\text{Ga}_{2}\mathrm{O}_{3}}$
after PAMM is found to be greatly improved. We believe this novel PAMM technique can provide new sights into the nanomanufacturing research towards next-generation semiconductors and further promote the development of
$\boldsymbol{\beta-\text{Ga}_{2}\mathrm{O}_{3}}$
-based electronic devices.