Thermal properties of high-k Hf_1-xSi_xO₂

Classical atomistic simulations based on lattice dynamics theory and Born core-shell model are performed to systematically study the crystal structure and thermal properties of high-k Hf_1-xSi_xO₂. The coefficients of thermal expansion, specific heats, Gr黱eisen parameters, phonon densities of states, and Debye temperatures, are calculated at different temperatures and for different Si-doping concentrations. With the increase of Si-doping concentration, the lattice constant decreases. At the same time, both the coefficient of thermal expansion and the specific heat at constant volume of Hf_1-xSi_xO₂ also decrease. Gr黱eisen parameter is about 0.95 at temperature less than 100 K. Compared with Si-doped HfO₂, pure HfO₂ has higher Debye temperature when temperature is less than 25 K, while it has lower Debye temperature when temperature is larger than 50 K. Some simulation results accord well with experimental data. We expect that our results will be helpful for understanding the local lattice structure and thermal properties of Hf_1-xSi_xO₂.