Polyethylene terephthalate (PET) has been modified by Si ion implantationwith a dose ranging from 1 x10^(16) to 2x10^(17) ions /cm^2 using a metal vapor vacuum arc (MEVVA)source. The surface morphology was observed by atomic force microscopy (AFM). The change in themicro-structure of Si implanted PET was observed with a transmission electron microscope (TEM). Itis believed that the change would improve the conductive properties and wear resistance. Theelectrical properties of PET have been improved via Si ion implantation. The resistivity ofimplanted PET decreased obviously with an increase in ion dose. When Si ion dose was 2x10^(17)cm^(-2), the resistivity of PET could be less than 7.9 Ω ? m. The surface hardness andmodulus increased obviously. The mechanical property of the implanted PET has been modified greatly.The hardness and modulus of Si implanted PET with a dose of 2 x 10^(17)/cm^2 are 12.5 and 2.45times greater than those of pristine PET, respectively. The area of cutting groove for Si implantedPET is narrower and shallower than those of the unimplanted PET. So the wear resistance is greatlyraised. In comparison with metal ion implantation, the improvement of mechanical properties isobvious in ion implantation into PET. Si ion beam modification mechanism of PET is discussed.
Co synthesis silicides with good properties were prepared using MEVVA ion implantation with flux of 25–125 μA/cm2 to does of 5×1017/cm2. The structure of the silicides was investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM analysis shows that if the ion dose is greater than 2×1017/cm2, a continuous silicide layer will be formed. The sheet resistance of Co silicide decreases with an increase in ion flux and ion dose. The formation of silicides with CoSi and CoSi2 are identified by XRD analysis. After annealing, the sheet resistance decreases further. A continuous silicide layer with a width of 90–133 nm is formed. The optimal implantation condition is that the ion flux and dose are 50 μA/cm2 and 5×1017/cm2, respectively. The optimal annealing temperature and time are 900°C and 10 s, respectively. The ohmic contact for power microwave transistors is fabricated using Co ion implantation technique for the first time. The emitter contact resistance and noise of the transistors decrease markedly, the microwave property has been improved obviously.
Nanometer TiN/AlN multilayers were prepared on silicon substrate by filtered vacuum arc deposition.The structures of the nanometer TiN/AlN multilayer were studied by using X-ray diffraction. The 12 nm TiN/AlN multiplayer is composed of cubic TiN structure and hexagonal wurzite AlN structure, but the 2 nm period multilayer is composed of face centered cubic structure TiN and AlN with strong (200) texture. The surface roughness, hardness and elastic modulus of multilayer are dependent on the period of multilayer. The hardness of the TiN/AlN multilayers is higher than that suggested by a simple rule of mixture. The peaking hardness of nanometer TiN/AlN multilayers at period of 2 nm is about 42 GPa, much higher than that of 12 nm. The wear resistance of the nanometer TiN/AlN multilayers was also studied.
