On the Atomic Kinetic Energies in Ceramic Oxides

Yacov Finkelstein,Rony Shneck,Raymond Moreh

doi:10.4236/msce.2017.512002

Abstract

We calculated the mean atomic kinetic energy, , of the X atom (X = Si, Ti, Hf, O) in some ceramic oxides, SiO2, TiO2 and HfO2 using the published partial vibrational density of states (PVDOS). These were simulated by means of lattice dynamics, molecular dynamics and density functional theory. The predicted values are compared to those recently obtained by electron Compton scattering (ECS), with an overall good agreement of ~4%. In accord with calculations, the ECS measurements reveal a small, but detectable, dependence of on the fine structural details of the oxide, e.g. whether it is in a crystalline or amorphous form, and whether it exhibits surface or bulk characteristics. This study illustrates the limitations and the potential of PVDOS simulations in predicting experimental atomic kinetic energies, and can be viewed as a promising approach for elucidating valuable structural and dynamical information of ceramic oxides and other materials.

Highlights

Ceramic oxides such as SiO2, TiO2 and HfO2 are fundamental dielectrics amongst a large family of atomic layer deposition (ALD) materials commonly used in semiconductors and micro-/nano-electronics technologies
Of key importance are the dynamical properties of ceramic oxides which may be studied via their vibrational spectra using IR, Raman and inelastic neutron scattering (INS) that provide fingerprints for clarifying their structure
Note that in silica some modes occur in the 1000 1200 cm−1 region while those of titania and hafnia the modes terminate at about 900 cm−1

Summary

Introduction

Ceramic oxides such as SiO2, TiO2 and HfO2 are fundamental dielectrics amongst a large family of atomic layer deposition (ALD) materials commonly used in semiconductors and micro-/nano-electronics technologies. The complexity of these technologies demands in some cases, cross-disciplinary research studies. Understanding the hoping mechanism of the O-atoms between surface oxygen vacancies in HfO2 involves the study of hafnia PVDOS [3] Another exemplifying case is that of amorphous silica (α-SiO2) which is widely used in semiconductor devices and optical fibers. In the present study we utilize the SE approach to deduce Ke(X) values of the atomic constituents in SiO2, TiO2, HfO2, by using their literature simulated PVDOS, and show that they are in good agreement with recent ECS measurements. An attempt is made to assign the measured values to specific structural characteristics of the studied oxides

Experimental Details

Mean Atomic Kinetic Energy Calculations

Results and Discussion

Technique

Summary