The uniform diamond films with 60 mm in diameter were deposited by improved DC arc plasma jet chemical vapor deposition technique. The structure of the film was characterized by scanning electronic microcopy(SEM) and laser Raman spectrometry. The thermal conductivity was measured by a photo thermal deflection technique. The effects of main deposition parameters on microstructure and thermal conductivity of the films were investigated. The results show that high thermal conductivity, 10.0 W/(K·cm), can be obtained at a CH4 concentration of 1.5% (volume fraction) and the substrate temperatures of 880-920 ℃ due to the high density and high purity of the film. A low pressure difference between nozzle and vacuum chamber is also beneficial to the high thermal conductivity.
Fe-doped amorphous Fe x C 1 x granular films were prepared on n-Si(100) substrates by d.c.magnetron sputtering.The structural properties of Fe x C 1 x films were investigated by X-ray diffraction(XRD),atomic force microscope(AFM) and Raman spectroscopy.The results show that the iron and carbon of as-deposited films are in amorphous state,and the Fe x C 1 x films are diamond-like carbon(DLC) films.After doping iron into the DLC films,a smooth surface morphology of the Fe x C 1 x films has been obtained with the surface roughness Ra of about 0.231 nm for x=18at%.The Fe x C 1 x films have good soft magnetic properties with the coercivity of approximately 20 Oe.A high positive magnetoresistance(MR) up to 93% with x=1at% was observed in a Fe x C 1 x granular film at 300 K.The resistance characteristic of Fe-C films is changed at about 230 K and the positive MR effect can be understood by the p-n heterojunction theory.
MA LeiLIU ZhongWuZENG DeChangYU HongYaZHONG XiaPingZHANG XiaoZhong
