Functionalized few-layer silicene nanosheets: stability, elastic, structural, and electronic properties

Abstract

This paper presents an ab initio investigation, performed in the framework of density functional theory, on the properties of functionalized few-layer silicene nanosheets, denoted as Si₂X₂ bilayers and Si₄X₂ trilayers with X = B, N, Al, and P. Searching for stable phases, we computed the structural, energetic, thermodynamic, dynamic, elastic, and electronic properties of those systems in several stacking configurations, labeled as AA′, AB, AA′A′′, and ABC. The results revealed that AA′-Si₂N₂, AB-Si₂N₂, AA′-Si₂P₂, and AB-Si₂P₂ bilayers, as well as ABC-Si₄B₂, ABC-Si₄Al₂, AA′A′′-Si₄P₂, and ABC-Si₄P₂ trilayers are all dynamically stable, based on their respective phonon dispersion spectra. Particularly, there is scarce literature regarding functionalized trilayer silicene systems and, in this work, we found four new nanosheet systems with interesting physical properties and promising applications. Additionally, according to their standard enthalpies of formation and by exploring their electronic properties, we established that those structures could be experimentally accessed, and we discovered that those silicene nanosheets are indirect band gap semiconductors when functionalized with N or P atoms and metallic with B or Al ones. Finally, we envision potential applications for those nanosheets in alkali-metal ion batteries, van der Waals heterostructures, UV-light devices, and thermoelectric materials.