Atomically thin, perforated graphene on c-plane sapphire functions as a nanoscale mask that enables GaN growth through thru-holes. We tune the perforated-area fraction fp by controlled O2-plasma exposure and quantify its impact on early-stage nucleation: the nucleation-site density scales with fp, while the nucleation-delay time decreases approximately as 1/fp. Time-resolved areal coverage and domain counts exhibit systematic fp-dependent trends. A kinetic Monte Carlo (kMC) model that coarse-grains atomistic events -- adatom arrival, surface diffusion, attachment at exposed sapphire within perforations, and coalescence (the first front-front contact between laterally growing domains) -- reproduces these trends using a constant per-site nucleation rate. Fitting the kMC simulation data yields onset times t0 for the nucleation delay that closely match independently observed no-growth thresholds (Set 1: 28.5s vs ∼30s; Set 2: 38s vs ∼35s), validating the kMC-experiment mapping and highlighting plasma dose as an activation threshold for plasma-induced through-hole formation in 2D materials. Together, experiment and kMC identify fp as a single, surface-engineerable parameter governing GaN nucleation statistics on perforated graphene masks, providing a quantitative basis and process window for epitaxial lateral overgrowth (ELOG)/thru-hole epitaxy (THE) workflows that employ two-dimensional masks.
@article{arxiv.2509.08275,
title = {Controlling GaN nucleation via O$_2$-plasma-perforated graphene masks on c-plane sapphire},
author = {Su Young An and Chinkyo Kim},
journal= {arXiv preprint arXiv:2509.08275},
year = {2025}
}