Fourfold increase of the ultraviolet (314 nm) electroluminescence from SiO2:Gd layers by fluorine co-implantation and flash lamp annealing

Efficient ultraviolet electroluminescence (UVEL) is obtained from Metal-Oxide-Silicon (MOS) structures with the SiO2 :Gd/F active layers prepared by flash-lamp annealing and Gd and F co-implantation. We observed a doubling of both the UVEL intensity and the defect related luminescence by increasing the fluorine concentration. This is due to suppression of the hot electron scattering on the donor-type level of the E’-center which number is reduced by the fluorine and increasing the optical active Gd3+ centres by Gd-F3 molecule formation. Also, fluorine co-implantation has no influence on the operating time of the MOS diode. Additionally, the flash lamp annealing doubled the ultraviolet electroluminescence from SiO2 layers implanted by gadolinium alone or in combination with fluorine. This is related to the suppression of cluster formation of rare earth atoms occurring during conventional annealing methods.