Low temperature 2D GaN growth on Si(111) 7 × 7 assisted by hyperthermal nitrogen ions

Maniš, Jaroslav; Mach, Jindřich; Bartošík, Miroslav; Šamořil, Tomáš; Horák, Michal; Čalkovský, Vojtěch; Nezval, David; Kachtík, Lukáš; Konečný, Martin; Šikola, Tomáš

doi:10.1039/d2na00175f

Cited by 2 publications

(1 citation statement)

References 30 publications

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“…A promising way to fabricate 2D GaN has been provided by the technique of migration-enhanced encapsulated growth based on epitaxial graphene [13]. Another method of 2D GaN growth has been realized by using the low-temperature droplet epitaxy technique on the Si(111) 7 × 7 surface [63].…”

Section: Ga Nmentioning

confidence: 99%

Many-Body Calculations of Excitons in Two-Dimensional GaN

Zhang

2023

Crystals

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We present an ab initio study on quasiparticle (QP) excitations and excitonic effects in two-dimensional (2D) GaN based on density-functional theory and many-body perturbation theory. We calculate the QP band structure using GW approximation, which generates an indirect band gap of 4.83 eV (K→Γ) for 2D GaN, opening up 1.24 eV with respect to its bulk counterpart. It is shown that the success of plasmon-pole approximation in treating the 2D material benefits considerably from error cancellation. On the other hand, much better gaps, comparable to GW ones, could be obtained by correcting the Kohn–Sham gap with a derivative discontinuity of the exchange–correlation functional at much lower computational cost. To evaluate excitonic effects, we solve the Bethe–Salpeter equation (BSE) starting from Kohn–Sham eigenvalues with a scissors operator to open the single-particle gap. This approach yields an exciton binding energy of 1.23 eV in 2D GaN, which is in good agreement with the highly demanding GW-BSE results. The enhanced excitonic effects due to reduced dimensionality are discussed by comparing the optical spectra from BSE calculations with that by random-phase approximation (RPA) for both the monolayer and bulk GaN in wurtzite phase. Additionally, we find that the spin–orbit splitting of excitonic peaks is noticeable in 2D GaN but buried in the bulk crystal.

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Section: Ga Nmentioning

confidence: 99%