The Study On The Fabrication And Optical Properties Of The Doped SiC Films

SiC films, doped with manganese (Mn) or with cobalt (Co) or with Mn and Co were prepared by the RF-magnetron sputtering. The as-deposited films were annealed in the temperature of 1050℃under argon ambient. The thin films have been characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Atomic force microscopy (AFM), and Photoluminescence (PL).The results showed that RF-magnetron sputtering is a high-speed, convenient method that can prepare high quality SiC thin films.The surface roughness of films increased by increasing annealing temperature. Mn or Co doping lead to a decrease of XRD peak of SiC films due to the lattice distortion and to weakening of Si-C bonds'related vibration peaks and to enhancing Si-O bonds. Meanwhile, a more intensive near band photoluminescence emission (414nm),which was approximately 1.3 times high in intensity,was observed at room temperature in Mn doped SiC films due to the increased Si vacancy concentration. A weaken emission also at 414nm, which was approximately 0.7 times in intensity, was observed in Co doped SiC films due to the decreased Si vacancy concentration. For co-doping of Co and Mn with a same total concentration, the luminecent intensity kept almost unchanged due to the compesation effect.SiC films with different Si / C ratio were prepared by the RF-magnetron sputtering and their optical properties were analyzed, particularly the changes of optical bandgap and related mechanism. The results showed that the as-deposited films areα-Si1-xCx films. Si and C are evenly distributed in the films. The bonds of films changed with the carbon content. The proportion Si-C bond formation at different carbon contents is affected by Si and C atoms ratio in the thin films. When Si atoms with large radius are the dominant, they are surrounded by the C atom with small radius. These Si atoms with positive electricity close to each other and have repulsive force which lead up to instability of Si-C bonds and act against the formation of Si-C bond. When C atoms are the dominant, they are surrounded the Si atom.These C atoms with negative electricity are far away from each other and the repulsive force could be neglected, so that the Si-C bonds formed are stable.