Study Of Photoluminescence And Electroluminescence From Silicon-based Lighting Materials

The properties of luminescence from Si-SiO2, Ge-SiO2, Al-Si-SiO2, Al-Ge-SiO2 thin films and the mechanisms of light emission have been studied. Films were deposited on p-Si substrates by radio frequency magnetron sputtering technique with a Si-SiO2 or Ge-SiO2 composite target or some pieces of Al wafers on the target. Some films were annealed in N2 ambience for 30 minutes at different temperature. The microstructure of films were characterized by XRD, XPS FTIR spectra.Under ultraviolet excitation, all the samples emit the comparable bands at 370nm 410nm 470mm 510nm but Al-Ge-SiO2 films haven't the emission band at 510nm. With the aid of PLE spectra and the dependence of PL on the annealing temperature, the possible mechanisms of light emission have been discussed. They all come from the luminescence centers(LCs) in the matrix of SiOx. Samples have a simple luminescence band peaked at 510nm under forward bias greater than 6V. Maybe it's because that the energy to excite the LC in the matrix is so low that the power of current can supply while others are relatively high or that the number of the corresponding LC is superior to that of others. Thus the PL and EL coincide with each other in some degree.To improve the luminescence efficiency and the intensity of luminescence, attempts by doping with Al element to keep it in the form of atom clusters under certain deposition condition have been proved useful.