First principle study of structural, elastic, mechanical and phonon properties of c-HfO2

Phonon transport mechanism of HfO2 ultrathin film with temperature-correction full-band Monte Carlo simulation

“…It can be found in figure 12(a) that the smaller phonon group velocity and heat capacity of HfO 2 leads to a larger slope of the film temperature distribution. In figure 12(b) the ITC is greater than the theoretical calculation value because the contribution of phonons not in the overlap frequency segment to the heat flux is not considered while utilizing equation (12). Based on atomic Green's function method [56], the ITC of the Si-based HfO 2 decreases with the increase of atomic mass ratio.…”

“…The theoretical thermal conductivity of ultrathin film was computed using the model proposed by Majumdar [48], and the calculated results were larger than the simulation results. The theoretical model is shown in equation (12), where κ f is the thermal conductivity of the film, κ b is the thermal conductivity of bulk material, and Kn f is the Knudsen number of the film. The mean free path (MFP) used in the computation of the Knudsen number is computed from the phonon information of bulk materials, which is much longer than that in ultrathin film [49], which also affects the theoretical results.…”

“…The thermal conductivity of HfO 2 ultrathin film measured by scanning thermal microscope and pump-probe time-domain thermal reflectometry is significantly smaller than that of bulk material [6,7]. The commonly used method in numerical simulation is to use the first-principles method and molecular dynamics to study the elastic, mechanical, and thermodynamic properties of different structures [8][9][10][11][12], as well as the improvement and verification of potential functions [13][14][15][16]. It can be seen that the thermodynamics-related research only stops at the computation of thermal conductivity and other parameters, and the thermodynamic properties and phonon transport mechanism of HfO 2 ultrathin film and the interface with substrates are barely studied.…”