The technology of modification of the CNT array on a silicon substrate using laser radiation of nanosecond duration has been developed. The energy regime of irradiation of the array is determined with the aim of aligning the nanotubes perpendicular to the substrate. Structuring of CNTs at a given area using impulse nanosecond radiation moving using a galvanometric scanner system is obtained. Patterning was carried out using pulsed laser radiation with a wavelength of 1064 nm, which was moved by means of galvanometric mirrors over the area of the CNT array. The spatial profile of the beam was Gaussian. The energy density of the pulse was in the range 0.4-2.2 J/cm². In order to obtain a homogeneous region of the CNT array after irradiation, the following parameters were set: the pulse duration was 100 ns, the radiation frequency was 30 kHz, at which the overheating of CNTs was minimized. The diameter of the laser beam at the focus of the laser was 20 μm. The moving rate of the laser beam of 500 mm/s was chosen in such a way so that individual pulses formed a continuous line with a laser beam overlap to compensate the changing in laser spot power along the diameter. Thus, the processed square 5×5 mm was formed by parallel lines 5 mm long, consisting of individual pulses located at a distance of 17 μm from each other. It is shown that the following effects are possible: CNT ablation, the effect of CNT alignment (straightening), singling, and “splicing” of individual CNTs in a single structure, as well as changing the morphology of the array itself. Nanotubes are less defective after laser modification. This is proved by Raman spectroscopy. The effect of CNT array structuring can be used to create new sensitive elements of photodetectors, solar cells, chemical sensors, temperature and pressure sensors, probes in microscopy and emitters.

Date Published: 30 April 2019
PDF: 8 pages
Proc. SPIE 11026, Nonlinear Optics and Applications XI, 110261A (30 April 2019); doi: 10.1117/12.2520991

Published in SPIE Proceedings Vol. 11026:
Nonlinear Optics and Applications XI
Mario Bertolotti; Alexei M. Zheltikov, Editor(s)