Preparation And Luminescence Of Tb-Doped Silicon Oxycarbide Film

In recent decades,there has been increasing research activity focused on silicon materials due to their excellent electrical and mechanical properties,and the abundant silicon resource on Earth.However,because of its indtrect band gap that limited its light emission.Electrons transfer from the conduction band bottom to the top of the valence band,needing to absorb or emit a phonon,which is much less likely than the electron direct transition to the photon.silicon-based luminescent materials are important optoelectronic materials.Therefore,the design of efficient and stable silicon-based luminescent materials is a key issue in optoelectronic technology.A proven effective strategy to overcome this problem is doping silicon-base luminescent materials with rare earth materials.This is strongly motivated by the facts,that the excellent luminescence properties of rare earth materials,the rich f-f transition electrons,the sharp peaks,the hige color purity,and the rare earth luminescence being influenced by the outside world.In addition,rare earth ions with +3 valence,f1 to f13 electronic layer contains unpaired electrons,the transition can produce luminescence,suitable doping into the luminescent material.Therefore,doping rare earth materials into silicon-based thin films is an important way to achieve silicon-based luminescence.In this paper,Tb doped matrix material SiC_xO_y films,in order to achieve the optimal luminescence of Tb ions.At first,the luminescence mechanism of SiC_xO_y films was studied.Strong luminescent amorphous silicon oxycarbide(a-SiCx Oy)films with different O content were prepared by very high frequency plasma enhanced chemical vapor deposition(VHF-PECVD)at a temperature of 250? by using the gas mixture of SiH4,CH4 and O2 as the precursor.The effect of O content on the luminescent properties and structure of SiC_xO_y thin films is investigated.It is found that the increase of O content results in remarkable photoluminescence(PL)with orange-red to blue shifting emission,which can be clearly observed with the naked eyes in a bright room.The PL of the a-SiCx Oy film is suggested from the nanoseconds recombination lifetime.The microstructure and the chemical compositions of the films were further investigated by Raman spectra,X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared absorption(FTIR)spectroscopy,respectively.Combining with the PL results and the analysis of the chemical bonds and microstructure present in the films,the main phase structure of the films and the change of the luminescent center with the O2 flow rate are the main reasons for the tunable light emission.The effect of C content and annealing temperature on Tb ions luminescence from Tb-doped SiO_xC_y films is investigated.Following,Tb-doped SiO_xC_y(Tb: SiO_xC_y)films were deposited by magnetron sputtering method.When proper C doping Tb:SiO2 films,the Tb ions photoluminescence(PL)intensity is enhanced owing to formation of nanosized Si clusters.Although continuing to increase C content,the Tb ions emission intensity is decreased.This is because of the increase of C content in the film,the oxygen defect excitation Tb ion luminescence is the main position,and nano-Si cluster exciton excitation intensity is stronger than the oxygen deficiency exciton excitation intensity.Afterwards,the film with the strongest emission was annealed at different temperatures.It was found that both the C content and the annealing temperature have a strong influence on the Tb ions emission intensity.Integrating the structural properties analysis,a detail discussion of these issues is presented and the optimal C content and annealing temperature are determined.