Enhancing emission and conduction of light emitting capacitors by multilayered structures of silicon rich oxide

Abstract

This work reports the morphological, electrical and luminescent characteristics of Light Emitting Capacitors (LECs) composed by Silicon Rich Oxide (SRO) multilayers. These multilayers alternate four conductive SRO layers (silicon excess of 12 or 14at%) with three light emitting SRO layers (silicon excess of 6at%). Transmission electron microscopy reveals that multilayers present well-defined nanoscale layers and interfaces in the multilayers. Furthermore, it is found that layers with high silicon content induce the formation of bigger silicon nanocrystals in the emitting layers as compared to single layers. When LECs are biased through a current-voltage measurement, an electroforming effect, where the current increases abruptly, is observed. This electroforming effect produces conductive trajectories arrays with high silicon content in the conductive SRO layers. These conductive paths allow to the LECs achieve higher current values with lower voltages preserving the luminescent characteristics of the emitting SRO layers. Consequently, it is demonstrated that silicon nanocrystals also act as sources of electro-hole pairs increasing the radiative recombination in the SRO defects. LECs that combine conductive and light emitting SRO films in a multilayered structure allow to enhance brightness and electrical characteristics compared to single layers. Depending on the conductive SRO layer preferential electroluminescence is produced in red or blue region.