PSI - Issue 65

Svetlana V. Ustiuzhanina et al. / Procedia Structural Integrity 65 (2024) 295–301 Ustiuzhanina S.V. et al. / Structural Integrity Procedia 00 (2024) 000–000

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other hand, the high chemical activity of low-dimensional materials allows their use in various gas sensors (Abbasi et al. (2019), Abbasi and Sardroodi (2017), Kistanov et al. (2019)). Therefore, many studies are aimed at finding such low-dimensional materials that are stable in environmental conditions, but at the same time retain their unique properties (Baimova et al. (2015), Kosarev et al.(2024). One of such materials are ternary compounds (Gregory et al. (2001)). For example, based on the first-principles predictions, the Sb 2 TeSe 2 monolayer has been proposed as a material for solar cells due its moderate band gap, high carrier mobility and power conversion efficiency (Wang et al. (2021)). Ab initio calculations have shown that the B 3 C 2 P 3 monolayer is highly sensitive and selective towards NO 2 and NO gases, while moisture hardly influences the adsorption of NO and NO 2 (Youn et al. (2024)). Simulation results have also shown an enhanced ion motion effects in CoMnN films due to a moderate Mn introduction, Tan et al. (2022). Very recently, great attention has been paid to ternary nitrides. For example, TiZnN 2 thin film has been proposed as a hydrophobic, highly stable, and cost-effective active layer in solar cells (George et al. (2023)). Thin films of Zn 2 VN 3 , Zn 2 NbN 3 , and Zn 2 TaN 3 have been discovered recently. Those thin films exhibit high ambient stability, moderate bandgap and high absorption value which make them promising for application as a diffusion barrier layer in tandem solar cells (Zakutayev (2021), Zhuk et al (2021), Zakutayev et al. (2022), Zhuk et al (2023)). In this work, chemical activity of novel Zn 2 (V,Nb,Ta)N 3 monolayers is studied using density functional theory(DFT)-based simulations. For that, most common environmental molecules, such as N 2 , CO 2 , NH 3 , NO, NO 2 H 2 O, and O 2 are used. In addition, the formation and the effect of point defects on carrier mobility is considered. 2. Theory and Methodology The model of the Zn 2 VN 3 , Zn 2 NbN 3 and Zn 2 TaN 3 monolayers is designed based on the structure of their bulk counterparts obtained in previous works (Stratulat et al. (2023), Zhuk et al. (2021)). These monolayers have an orthorhombic lattice with the lattice parameters are a = b = 5.63 Å, a = b = 5.77 Å, and a = b = 5.78 Å, respectively. Figures 1a and b show top and side views of the optimized 3x3x1 supercell of the cells of Zn 2 (V,Nb,Ta)N 3 monolayers. Thermodynamic stability of Zn 2 (V,Nb,Ta)N 3 monolayers was confirmed in research (Kistanov et al. (2023), Kistanov et al. (2023)). Simulations were conducted within the DFT framework as implemented in the Vienna Ab initio Simulation Package (VASP) (Kresse and Furthmuller (1996)). The geometry optimization calculations were performed using the PerdewBurkeErnzerhof functional under the generalized gradient approximation, and the HSE06 hybrid exchange-correlation functional was used for electronic structure calculations. The atomic force threshold of 10 4 eV/Å and total energy threshold of 10 8 eV were set. Periodic boundary conditions were applied in the in-plane transverse directions. To avoid the interaction of the replicated cells, a vacuum space of 20 Å was introduced to the out-of-plane direction. The van der Waals interaction between the surface and the molecules were treated using the DFT-D3 dispersion correction (Grimme et al. (2010)).

Fig. 1. Structure of a 3x3x1 supercell of Zn 2 (V,Nb,Ta)N 3 monolayers. Blue, gray, and red balls correspond to the N, Zn, and V(Nb,Ta) atoms.