Energy Transfer by Gd to ion Implanted Ce and Er Atoms in Metal-Oxide-Silicon-based Light Emitting Diodes

The excitation mechanism of electroluminescence (EL) of cerium and erbium ions co-implanted with gadolinium into the SiO2 layer of MOSLEDs was investigated. Ce and Er ions were implanted into SiO2 with a concentration of 1% and 2%, respectively, subsequently implanted by gadolinium ions with concentrations of 0.5, 1.5 and 3%. Silicon dioxide containing cerium co-implanted with Gd exhibits two different excitation mechanisms: direct Ce3+ ion excitation by hot electrons and transfer of energy from 6PJ energy level of Gd to 5d energy state of Ce leading to an increase of the EL of Ce in the blue region. The EL observed from the sample containing 3% of Gd was 5 times higher in comparison with samples implanted only by Ce. The Er implanted SiO2 exhibits the typical peak at 1540 nm and weak luminescence in the green and blue region. Two green peaks correspond to the transitions from 2H11/2 and 4S3/2 to 4I15/2 and blue peaks to those from 2H9/2 and 4F5/2 to 4I15/2. The additional implantation of Gd leads to an increase of luminescence from Er3+ lines in the visible region caused by the energy relaxation from the Gd excited level 6PJ to the higher energy levels of erbium, whereas it has no influence on the infrared luminescence at 1.54 mm.