Kinetic study of nanofabrication on gold films by atomic force microscope tips under laser irradiation

Abstract

Recently, scanning probe microscope (SPM) has become a promising technique for nanofabrication. In this paper, we present a novel method of nano-fabrication, namely, nano-fabrication by atomic force microscope (AFM) tips under laser irradiation. The SPM was operated as an AFM. During imaging and nano-fabrication, the AFM is in constant force mode. The tip is fixed with the sample moving via a tube scanner. Nano-lithography software controls the scanner motion in x and y directions. The SPM has an open architecture allowing an external laser beam incident on the tip at an incident angle between 0 to 45°. A vertical polarized Nd:YAG pulsed laser with a pulse duration of 7 ns was focused on the tip. An electrical shutter was introduced to switch the laser irradiation. Alignment between the laser beam and the tip was performed under a high-power charge coupled device (CCD) microscope. Nano-fabrication was carried out on gold films deposited on n-type Si substrates using the physical deposition method. The kinetics of the nanostructure fabrication has been studied. Craters were created in air ambient under different laser pulse numbers, pulse energies and tip force. The feature size of the craters, which are in the nanometer scale, increases with the pulse number, pulse energy and the tip force. This technique has potential applications in the high-density data storage.