Structural, electronic, and dielectric properties of amorphous hafnium silicates

摘要

Using first-principles calculations, we have investigated the evolution of the structural, electronic, and dielectric properties of amorphous Hf_(1-x)Si_xO_2 over the entire range of composition. Our results show that the Si-rich Hf-silicates possess distinct structural characteristics from the Hf-rich ones. The electronic band gaps calculated using hybrid density functional agree well with the experiments, exhibiting nonlinear variation with the Si content. Different from the previous theoretical studies, our results support a nonlinear dependence of the dielectric constants on the composition of silicates, which is mainly attributed to the rapid reduction of the low-frequency vibrational motions of Hf atoms with increasing the Si content.