White electroluminescence from a gadolinium doped Si nanocluster enriched SiO2-SiON interface region

Efficient white electroluminescence is obtained from metal-oxynitride-oxide-silicon (MONOS) structures with a silicon rich SiO2/SiON interface as an active layer. Samples containing only silicon show white electroluminescence (EL) under constant current excitation of 500 A. The EL spectra consist of three main bands associated with the neutral oxygen vacancy at 430 nm (NOV), E’ centers at about 550 nm and nonbridging oxygen hole centers (NBOHC) peaking at 650 nm. After Gd codoping into the SiO2:Si-nc layer the light emitted from the MONOS structure observed by naked eye is clearly white but the constant current needed for the EL excitation is reduced five times. Additionally, a fourfold increase of the electroluminescence power efficiency after Gd codoping was observed.