Deposition of thin polytetrafluoroethylene (PTFE) films using fundamental pulses of a Nd³⁺: YAG laser

Abstract

Pulsed laser deposition of PTFE was carried out using a 1064-nm laser. Two different pulse regimes were examined to determine their effectiveness in causing deposition. The first of these consisted of a 20-ns Gaussian pulse, while the second was a pulse train comprising twenty 1-μs pulses with a total duration time of 100-μs. The main feature of the deposition technique that we present in this work is that ablation is induced by the efficient photothermal sensitization of graphite particles that are used to lightly dope (0.1 wt. %) a PTFE target. Both of the pulse regimes produced thin films whose infrared spectra were similar to that of PTFE. For the ns-pulse, however, carbon particles were contained in the deposited films. This behavior can be easily interpreted within the framework of photothermal ablation. For the μs pulse train, homogeneous heating is achieved due to the long thermal diffusion length, which is comparable to the average distance between the graphite particles used to dope the PTFE target. The thin PTFE films are deposited mainly by the mechanism of monomer re-polymerization. The present study demonstrates that near-infrared lasers of the μs-pulse type, which are versatile, economical and widely used in industry, are capable of the deposition of PTFE.