Correlation between surface scaling behavior and surface plasmon resonance properties of semitransparent nanostructured Cu thin films deposited <i>via</i> PLD

Abstract

The surface scaling behavior of nanostructured Cu thin films, grown on glass substrates by the pulsed laser deposition technique, as a function of the deposition time has been studied using height-height correlation function analysis from atomic force microscopy (AFM) images. The scaling exponents <i>α</i>, <i>β</i>, <i>1</i>/<i>z</i> and <i>γ</i> of the films were determined from AFM images. The local roughness exponent, <i>α</i>, was found to be ∼0.86 in the early stage of growth of Cu films deposited for 10 minutes while it increased to 0.95 with a longer time of deposition of 20 minutes and beyond this, it was nearly constant. Interface width <i>w</i> (rms roughness) scales with depositing time (<i>t</i>) as ∼ <i>t</i> ^<i>β</i> , with the value of the growth exponent, <i>β</i>, of 1.07 ± 0.11 and lateral correlation length <i>ξ</i> following <i>ξ</i> = <i>t</i> ^{<i>1</i>/<i>z</i>} and the value of <i>1</i>/<i>z</i> = 0.70 ± 0.10. These exponent values convey that the growth dynamics of PLD Cu films can be best described by a combination of local and non-local models under a shadowing mechanism and under highly sticking substrate conditions. From the scaling exponents and power spectral density function, it is concluded that the films follow a mound like growth mechanism which becomes prominent at longer deposition times. All the Cu films exhibited SPR properties where the SPR peak shifts towards red with increasing correlation length (<i>ξ</i>) whereas bandwidth increases initially with <i>ξ</i> and thereafter decreases gradually with <i>ξ</i>.