Development and properties of all-dielectric and metal-dielectric heterostructures at atomic scale

Heterostructures have increasingly attracted attention in recent times to enable various optoelectronic and photonic applications. In this Dissertation, atomic scale heterostructures of two technologically relevant oxides, such as, Al2O3 and TiO2 were developed by plasma enhanced atomic layer deposition (PEALD) technology. Their growth, composition, dispersion relation, and optical bandgap were systematically studied by means of various state of the art characterization methods. The dispersion spectra and the indirect optical bandgap of the heterostructures depend on the ratio of the two oxides, while the bandgap is very sensitive to the thicknesses of the barrier and quantum well layers. A significant blue shift of the absorption edge has been obtained by decreasing the TiO2 (quantum well) thickness down to about 0.5 nm. This study unfolds the possibility of achieving quantizing effects using dielectric heterostructures enabled by the control of layer thickness and properties down to an atomic scale. Furthermore, a unique combination of metal-dielectric heterostructure using Ir and Al2O3 are introduced. Their structural-property relationships were determined by various spectroscopic and microscopic techniques. Precisely tuning the ratio of the constituents provided by the ALD technology ensures the tailoring of the dispersion spectra along with a transition from effective dielectric to metallic heterostructures. Following this, the development of epsilon-near-zero metamaterials with tunable dielectric constants was explored by precisely varying the composition ratio of such heterostructures. The impact of such heterostructures in nonlinear optical processes, such as, second harmonic generation has also been examined. Altogether, this Dissertation enables a path towards atomic scale processing of tailored heterostructures demonstrating an extension of the material basis available for novel optical functionalities.