Thermal properties of high-k Hf1−xSixO2

Abstract

Classical atomistic simulations based on the lattice dynamics theory and the Born core-shell model are performed to systematically study the crystal structure and thermal properties of high-k Hf1−xSixO2. The coefficients of thermal expansion, specific heat, Grüneisen parameters, phonon densities of states and Debye temperatures are calculated at different temperatures and for different Si-doping concentrations. With the increase of the Si-doping concentration, the lattice constant decreases. At the same time, both the coefficient of thermal expansion and the specific heat at a constant volume of Hf1−xSixO2 also decreases. The Grüneisen parameter is about 0.95 at temperatures less than 100 K. Compared with Si-doped HfO2, pure HfO2 has a higher Debye temperature when the temperature is less than 25 K, while it has lower Debye temperature when the temperature is higher than 50 K. Some simulation results fit well with the experimental data. We expect that our results will be helpful for understanding the local lattice structure and thermal properties of Hf1−xSixO2.