Thermal behavior and matrix-assisted pulsed laser evaporation deposition of functional polymeric materials thin films with potential use in optoelectronics

Abstract

Thermal behavior studies of several polymers, i.e. polyvinyl chloride (PVC), polyacrylic acid (PAA), and polyaniline (PAni), together with thin film deposition by a MAPLE technique, are presented. Thermal stability studies are important before attempting any laser-assisted processing of such materials, as this provides a better understanding of their molecular behavior, to assess the evolution and dynamics of the deposition. Thin films were grown on silicon substrates by means of matrix-assisted pulsed laser evaporation (MAPLE) using a Nd:YAG laser (266 and 355nm, 7ns pulse duration). Above the fluence of ~0.7J/cm2 the polymeric films are highly non-uniform due to the transferring of matrix-droplets and/or clusters from the target. At low fluence, typically between 0.1 and 0.5J/cm2, the polymeric films are intact; the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the films. The important question of polymeric molecules integrity in the films with respect to that of the targets is discussed, in relation to their properties, and compared to data available in the literature.