Statistical characterization of thermally evaporated roughCaF2films

Abstract

Thermal deposition of CaF2 onto a glass substrate creates a nanoscale rough surface. A series of samples with differing nominal CaF2 film thicknesses have been fabricated, and the topography has been investigated using atomic force microscopy. Measured values for the statistical characterization of the samples are presented including the exponents describing the scaling behavior of the surfaces. We find that the roughness exponent alpha=0.88+/-0.03 , the growth exponent beta=0.75+/-0.03 , and the dynamical exponent z=alpha/beta=1.17+/-0.06 . We also measure the multifractal spectra and nearest neighbor height difference probability distribution. The results are consistent with noise dominated by a power-law distribution with exponent mu+1 approximately equal to 4.6. Profilometer measurements were used to determine the porosity phi of the deposited films, which we find to be constant for all film thicknesses with phi approximately 0.46 .

A spectroscopic investigation of the shape dependency of gold nanoparticles grown on roughened surfaces

“…It is well known that deposition of CaF 2 thin films result in a roughened surface with root-mean-square (RMS) surface roughness proportional to the CaF 2 film thickness [29]. Therefore, CaF 2 is used to deliberately and controllably roughen the substrate surfaces.…”

Ion transport in nanocrystalline CaF2 films

“…22 On glass substrates, CaF 2 films grown at room temperature showed a constant porosity of 46% by atomic force microscopy (AFM) for all thicknesses in the range 50-500 nm. 23 Based on these studies, CaF 2 films grown below ∼300 °C can be expected to exhibit small grain sizes and substantial porosity.…”