Ion beam synthesized nanoclusters for silicon-based light emission

Strong blue and violet photoluminescence (PL) and electroluminescence (EL) at room temperature has been achieved from thin SiO2 layers implanted with group IV elements. Thermally grown SiO2 films with thicknesses between 130 and 500 nm were implanted kith Si. Ge or Sri ions followed by different annealing procedures. Based on PL and PL excitation spectra we tentatively interpret the blue-violet PL as due to a T-1 - S-0 transition of an oxygen deficiency center. The strong EL is well visible with the naked eye and reaches a pokier efficiency, of up to 5 x 10(-3) for Ge. Whereas the EL intensity shows a linear dependence on the injection current for Ge-rich layers. the shape of the EL spectrum remains unchanged. It was found that the I-V characteristics shift to lower applied electric fields with increasing implantation fluence. Furthermore. it is assumed that the luminescence centers will be excited either by field ionization or by the scattering of hot electrons. Finally. the suitability of ion implanted silicon dioxide layers Cor optoelectronic applications is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.