Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

Abstract

This article theoretically explores the formation of dumbbell (DB)-like structures by elemental adsorption on the recently synthesized C3N monolayer. Owing to the repulsion from N atoms, different elements from groups III, IV, and V (B, C, Si, Ge, P, and As) have been examined to form DB-like cages when adsorbed on the opposite sides of the substrate. After establishing the dynamical and thermodynamic stability of these materials, their mechanical durability is analyzed. DBs formed by adatoms like P and As provide the highest in-plane stiffness while that by B exhibits the highest Poisson ratio. The ultimate tensile strain turns out to be quite high (around 18%) for the DB C3NP and C3NAs. Electronic band structure depicts semimetallic and semiconducting characteristics depending on the type of adsorbate that can be further tuned via external strain. Both DB C3NP and C3NAs undergo an indirect-to-direct band gap transition, while the semimetals show band gap opening of the order of meV under applied tension. The presence of space–time inversion symmetry with a well-known effective low-energy tight-binding Hamiltonian easily captures the event of linear band crossings in these materials. The valence orbital theory also nicely explains the origin of Dirac cones as well as the semiconducting indirect band gaps. There is visible anisotropy in the Fermi velocity, which can embrace high values such as 7.5 × 105 ms–1 at a specific direction, and this inhomogeneity measure is remarkably high (around 90%) for the Dirac materials. Electronic transport properties such as carrier-dependent effective mass and mobility also possess anisotropies by their very exotic nature. The findings here highlight a distinct class of 2D carbon nitrides with anisotropic Dirac semimetals and indirect gap semiconductors with plausible synthesis routes, which show great potential in nanodevice applications.

C3N based heterobilayers: a potential platform to explore optoelectronic and thermoelectric properties

“…This is also considered to be a very promising approach to tackle the bandgap hurdle of mighty graphene meanwhile preserving its excellent electronic properties. Since the arrival of graphene in 2004, an immense amount of attention has been given, from pushing its limitations as zero bandgap material to finding different stackings or morphological substitutes [5][6][7][8][9][10][11] which gave rise to a wider range of possibilities in fields like photocatalytic [12,13] activities, magnetic [14,15] applications or waste-heat management [16][17][18][19]. In recent years, many carbon-based 2D semiconductors have turned out to be quite of use due to their diverse optical, electronic, and thermal properties [20][21][22].…”