Super Resolution Nanofabrication On Semiconductor And Polymer Materials By Using Femtosecond Laser

Femtosecond laser has high peak power and ultrashort pulse width, there is almost no heat effect during femtosecond laser material interaction.Therefore, since the birth of femtosecond laser, femtosecond laser nanofabrication was attracted the scientist’s attention and shows a good application prospect. The works demonstrated in the dissertation include:the experimental system was constructed for fabricating single nanogroove structure based on femtosecond laser induced periodic ripples. The single nanogroove and nanosquare were realized on ZnO crystal. The experimental system was constructed for superresolution polymer nanofabrication based on the stimulated emission depletion method and the polymer nanostructures with resolution less than 100 nm was fabricated. The details are summarized as follows:(1) The experiment system was set up for single nanogroove nanofabrication. Because linear polarization laser can induce nanogroove on the surface of ZnO, single groove was fabricated with width of about 30nm by using the water immersion objective lens with numerical aperture NA=1.2 through precise control of laser power and pulse number. We have researched the formation of nanogrooves under different femtosecond laser fluence and fabrication speed. We prepared nanogratings with periods of 150nm,300nm and 1000nm, and the nanosquares with dimensions of 150nm×150nm and 150nm×250nm.(2) The experimental system was set up for superresolution polymer nanofabrication based on the stimulated emission depletion method. In the experiment, 800nm femtosecond laser and 532nm donut continous wave laser worked as polymerization laser and depolymerization laser, respectively. The gold nanoparticle was used to scan the focuses of the polymerization laser and the depolymerization laser, and two photomultiplier tubes were used to detect the backreflect light to get the focuses’ intensity distributions. We used motorized optical mount to insure the surface of the substrate parallel to the vertical movement plane of the pizeo stage. Meanwhile, the laser focuses were located at the substrate-photoresist interface by fabricating the polymer dot. We researched the relationship between the width of polymer nanoline and the depolymerization laser power, and had realized the nanoline with the minimum width of 93nm. At the same time, we had researched the relationship under different polymerization light power. We researched the relationship between the diameter of polymer nanodot and the depolymerization laser power, and had realized the nanodot with the minimum diameter of 81nm.