Electroluminescence properties of the $Gd3+$ ultraviolet luminescent centers in $SiO2$ gate oxide layers

Electroluminescence (EL) properties in the ultraviolet (UV) range were studied on Gd-implanted indium tin oxide/$SiO2:Gd∕Si$ metal-oxide-semiconductor light emitting devices. The efficient UV line at $316nm$ from $Gd3+$ centers shows a maximum power density of $2mW∕cm2$ and a quantum efficiency above 5%. The $Gd3+$ luminescent center has an excitation cross section above $7.4×10−15cm2$ with an EL decay time around $1.6ms$ at a Gd concentration of 3%. A decrease of the EL efficiency is observed by a cross relaxation at a high Gd concentration and by clustering of Gd atoms at an annealing temperature of $1000°C$⁠. A strong quenching of the UV EL due to electron trapping around optically active $Gd3+$ centers is observed during the injection of hot electrons.