A First-Principles Study on the Electronic, Thermodynamic and Dielectric Properties of Monolayer Ca(OH)(2) and Mg(OH)(2)

We perform first-principles calculations to explore the electronic, thermodynamic and dielectric properties of two-dimensional (2D) layered, alkaline-earth hydroxides Ca(OH) [Formula: see text] and Mg(OH) [Formula: see text]. We calculate the lattice parameters, exfoliation energies and phonon spectra of monolayers and also investigate the thermal properties of these monolayers, such as the Helmholtz free energy, heat capacity at constant volume and entropy as a function of temperature. We employ Density Functional Perturbation Theory (DFPT) to calculate the in-plane and out-of-plane static dielectric constant of the bulk and monolayer samples. We compute the bandgap and electron affinity values using the HSE06 functional and estimate the leakage current density of transistors with monolayer Ca(OH) [Formula: see text] and Mg(OH) [Formula: see text] as dielectrics when combined with HfS [Formula: see text] and WS [Formula: see text] , respectively. Our results show that bilayer Mg(OH) [Formula: see text] (EOT∼0.60 nm) with a lower solubility in water offers higher out-of-plane dielectric constants and lower leakage currents than does bilayer Ca(OH) [Formula: see text] (EOT∼0.56 nm). Additionally, the out-of-plane dielectric constant, leakage current and EOT of Mg(OH) [Formula: see text] outperform bilayer h-BN. We verify the applicability of Anderson’s rule and conclude that bilayers of Ca(OH) [Formula: see text] and Mg(OH) [Formula: see text] , respectively, paired with lattice-matched monolayer HfS [Formula: see text] and WS [Formula: see text] , are effective structural combinations that could lead to the development of innovative multi-functional Field Effect Transistors (FETs).