The Preparation And Characterization Of Silicon-silicon-carbon-oxygen Thin-film Light-emitting Materials

Along with the reduction of feature size and chip size, the electron drift speed becomes the bottleneck of increasing chip operating speed. It is an effective way to break through this bottleneck to use the fastest light signal to replace the original electrical signal to carry on the information transmission and processing. And the silicon-based light-emitting materials become luminescent device's best choice because its compatibility with the manufacture of the ultra large scale integrated circuits (ULSI) silicon planar technology. However, increasing the luminous efficiency is the key point for these materials to obtain widely application. The monocrystalline silicon is indirect band gap material, which is difficult to meet luminescent device's requirements for its low radiative recombination efficiency. In contrast, the nano-structure thin films have broader application prospects in the field of luminescent device, light survey component, electro-optical integration and sensors because of its electro-optical properties and low cost.In this work, after comprehensively summarize and analyse the properties and preparing methods for different Si based light emitting materials, the SiCO and Al doped SiCO compound thin films were prepared on N-type Si using magnetron sputtering technology and then the samples were annealed by Rapid Thermal Processing(RTP). The modern analytical techniques such as Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), X-Ray Diffraction (XRD), Fourier Transform Infrared Transmission (FTIR), Fluorescence Spectroscope (PL) were used to characterize the surface texture, chemical composition, chemical bonding status, crystal structure and photoluminescence properties of the samples.The SiC target sputtering power and working gas pressure have an obvious impact on deposition rate and surface topography of SiCO thin-films. The optimum sputtering power and working gas pressure are 150W and 1.2Pa respectively. With sputtering power's increase, the deposition rate increases, but does not assume the linear relationship, the surface particle size increases first and then decreases. With the working gas pressure increases the deposition rate increases first and then decreases, when the pressure is 1.2Pa the deposition rate is fastest. And when the gas pressure is in the range between 1.0Pa and 1.2Pa, the films surface is more flat.The analysis results indicated that the chemical composition of the SiCO thin films is complex, which include: Cystal and amorphous SiO₂, Small cystal SiC pellet,α-Si_1-xC_x,μc-Si, O dopedα-Si, minim C-groups. After 600℃annealing, the thin films emitte two illumination peaks located at 370nm and the 470nm, we deduced that its illumination mechanism is: The electrons first absorb different energy photons to jump to the SiO₂ oxygen vacancy defects, amorphous SiO₂ oxygen vacancy defects or the nanometer crystal 6H-SiC energy level, then partial excited electrons transit to the Si neutral oxygen vacancy defect (O3≡Si-Si≡O3) with the assistant of multi-phonon compounding with the holes and then emitted the corresponding 370nm PL peak; partial excited electrons transit to the the crystal 6H-SiC grain surface defect deathnium centers with the assistant of multi-phonon and compound with the holes to emitte the corresponding 470nm PL peak.The components of Al doped SiCO thin films have no obvious change. However the introduction of Al promoted the Si crystal grain formation, at the same time there presented the Si-O-Al chemical bonds in the Al doped thin films. After 600℃annealing, the photoluminescence is strongest and there presentes a strong illumination band between 370nm and 470nm centered at 412nm, we deduced that its illumination mechanism is: The electrons absorbing different energy photons excitated to the energy level generated by Si-O, O≡Si-Si≡O oxygen vacancy defects or Si-O-Al bonds. Then the active electrons transmit to the nanometer Si crystal grain surface defect centers with the assistant of multi-phonon and compound with the holes to emitte the corresponding PL peak, and its best excitated wave length is 273nm corresponds to SiO₂ oxygen defects energy level.