Comparative analysis of the electronic energy structure of nanocrystalline polymorphs of Y2O3 thin Layers: Theory and experiments

The results of fabrication and characterization of atomic structure of nanocrystalline thin layers of Y2O3 in cubic and monoclinic phases is reported. Experimental data demonstrate crystalline ordering in nanocrystalline films with average grain size of similar to 10-14 nm both for cubic and monoclinic studied structures. Density Functional Theory (DFT) based simulations demonstrate insignificant differences of electronic structure of these phases in the bulk and on the surfaces. Theoretical modeling also pointed out the significant broadening of valence and conductive bands caused by means of energy levels splitting in agreement with experimental data (X-ray photoelectron and photoluminescence spectra). The presence of various intrinsic and extrinsic defects (including surface adsorption of carbon mono- and dioxide) does not promote visible changes in electronic structure of Y2O3 surface for both studied phases. Optical absorption and luminescence measurements indicate insignificant bandgap reduction of Y2O3 nanocrystalline layers and the very little contribution from defect states. Simulation of extrinsic compression and expanding demonstrate stability of the electronic structure of nanocrystalline Y(2)O(3 )even under significant strain. Results of comprehensive studies demonstrate that yttrium oxide based nanocrystalline layers are prospective for various optical applications as a stable material.

Automated summary

This article reports the fabrication and characterization results of nanocrystalline thin layers of Y2O3 in cubic and monoclinic phases. Experimental data show crystalline ordering in nanocrystalline films with an average grain size of 10-14 nm for both structures. Density Functional Theory (DFT) simulations demonstrate insignificant differences in the electronic structure of these phases. Theoretical modeling and experimental data reveal the broadening of energy levels splitting in valence and conductive bands due to defects, while surface adsorption of carbon compounds does not significantly change the electronic structure.