Photoluminescence and stoichiometry correlation in nanocrystalline EuOx thin films: Tunable colour emission

Abstract

The development of broadband and ultra-compact optoelectronic devices relies on the possibility of fabricating bright and tunable emitters at the nanoscale. Here we show emission from EuOx (1 ≤ x < 1.4) thin films on Silicon formed by nanocrystals with average sizes in the range of 5 nm. The photoluminescence emission of the nano-EuOx films is tunable as a function of the oxygen concentration changing from a green broadband Eu2+−related emission to a narrow red Eu3+−related emission. To achieve these results has been instrumental the use of a new methodology specially designed to achieve high quality europium oxide films whose compositional properties are controlled by the growth base pressure and preserved thanks to a chemically stable and transparent cover layer of Al2O3. Our findings confirm the outstanding p otential of nanostructured EuOx films as “onecompound” optical elements with tunable emission properties for their implementation in integrated silicon-based devices