Zhengjie Fan

Nanomanipulation of Carbon Nanotubes with the Vector Scanning Mode of Atomic Force Microscope

The miniaturization of electronics devices into the nanometer scale is indispensable for next generation semiconductor technology, and CNTs are considered to be the promising candidates for the future nanoelectronics devices with being manipulated to the appropriate location in the manufacturing process of nanodevices. So the new vector scanning mode nanomanipulation is proposed and studied through the nanomanipulation experiments of nanoparticles and carbon nanotubes. According to the specific vectors, carbon nanotubes can accurately achieve the specified operation. And in the movement of carbon nanotubes, the deformation and rotation appear at times, which is caused by many factors, such as material itself properties, the size and direction of propulsive force of AFM tip, the adhesion between carbon nanotubes and substrate surface. In addition, under the influence of many factors, the carbon nanotubes can be manipulated without the indentation or other mechanical damages at the contact position between carbon nanotubes and AFM probe tip due to high elasticity and strength, etc, but the indentation become obvious in the nanomanipulation process of polystyrene nanoparticles because of own property. So, the new vector scanning mode nanomanipulation, based on AFM system, is demonstrated that it is an effective and reliable technique for manipulation of carbon nanotubes for the future nanodevices.

The influence of pre-melting in laser drilling with temporally modulated pulse

ABSTRACT Laser drilling by temporally modulated pulse is a promising technique and has many advantages compared with normal pulse drilling. In this work, the effect of modulated pulse comprising pre-heating front and sharp trail was mainly studied. The function of the former was to pre-melt the radiated material, and the latter was to expel the liquid melt from the molten pool, thus to form a blind hole. While the trail subpulse was kept constant, the difference in the pre-heating subpulse parameter could cause a considerable influence on the hole quality and drilling efficiency. The depth and volume of the molten pool were proportional to the pre-heating energy, and inversely proportional to the pre-heating duration. With pre-heating subpulses of proper parameters, the sharp trail subpulse was very effective in expelling the melt liquid, leaving only a small quantity of melt to re-solidify as the recast layer, which was observably thinner compared with the holes drilled using the normal pulse mode. In the pre-melting process, the directional melt flow and heat conduction were found to be the reasons why the deep melting phenomenon had occurred.