Controlling GaN nucleation via O$_2$-plasma-perforated graphene masks on c-plane sapphire
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915488372621312 |
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| author | An, Su Young Kim, Chinkyo |
| author_facet | An, Su Young Kim, Chinkyo |
| contents | 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 $f_p$ by controlled O$_2$-plasma exposure and quantify its impact on early-stage nucleation: the nucleation-site density scales with $f_p$, while the nucleation-delay time decreases approximately as $1/f_p$. Time-resolved areal coverage and domain counts exhibit systematic $f_p$-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 t$_0$ for the nucleation delay that closely match independently observed no-growth thresholds (Set 1: 28.5s vs $\sim$30s; Set 2: 38s vs $\sim$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 $f_p$ 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_08275 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Controlling GaN nucleation via O$_2$-plasma-perforated graphene masks on c-plane sapphire An, Su Young Kim, Chinkyo Materials Science Mesoscale and Nanoscale Physics 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 $f_p$ by controlled O$_2$-plasma exposure and quantify its impact on early-stage nucleation: the nucleation-site density scales with $f_p$, while the nucleation-delay time decreases approximately as $1/f_p$. Time-resolved areal coverage and domain counts exhibit systematic $f_p$-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 t$_0$ for the nucleation delay that closely match independently observed no-growth thresholds (Set 1: 28.5s vs $\sim$30s; Set 2: 38s vs $\sim$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 $f_p$ 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. |
| title | Controlling GaN nucleation via O$_2$-plasma-perforated graphene masks on c-plane sapphire |
| topic | Materials Science Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2509.08275 |