Abstract

We have previously reported how simultaneous chemical sputtering and plasma polymerization in a capacitively coupled r.f. plasma diode system can lead to polymer films in which small metal clusters (10Å-100 Å) are uniformly dispersed throughout. Post deposition laser irradiation of such a metal containing polymer film leads to migration and coalescence of gold clusters as soon as a second order phase transition associated with the polymer glass transition temperature, T_g, is surpassed. Starting with such a metal containing dielectric polymer film having a metal volume fraction below electrical percolation and then subjecting it to laser irradiation brings about metal coalescence into a continuous metal medium within spatial dimensions controlled by the laser beam and showing bulk conductivity. Likewise, laser induced cluster coalescence can lead to controlled growth in cluster size and shape accompanied by dramatic changes in optical transmission/reflection characteristics in keeping with predictions by Effective Medium Theories.^(1,2) Using a pulsed Kr⁺ laser at 647 nm with pulse width of 150 nsec gave sharp optical contrast threshold at 4 mW laser power. Using an unfocused Kr⁺ laser adjusted to deliver 2x10⁴ watts/cm² induces changes in electrical conductivity by greater than 10 orders of magnitude.

© 1987 Optical Society of America