Early stages of growth of gold layers sputter deposited on glass and silicon substrates

Abstract

Extremely thin gold layers were sputter deposited on glass and silicon substrates, and their thickness and morphology were studied by Rutherford backscattering (RBS) and atomic force microscopy (AFM) methods. The deposited layers change from discontinuous to continuous ones for longer deposition times. While the deposition rate on the silicon substrate is constant, nearly independent on the layer thickness, the rate on the glass substrate increases with increasing layer thickness. The observed dependence can be explained by a simple kinetic model, taking into account different sticking probabilities of gold atoms on a bare glass substrate and regions with gold coverage. Detailed analysis of the shape of the RBS gold signal shows that in the initial stages of the deposition, the gold layers on the glass substrate consist of gold islands with significantly different thicknesses. These findings were confirmed by AFM measurements, too. Gold coverage of the silicon substrate is rather homogeneous, consisting of tiny gold grains, but a pronounced worm-like structure is formed for the layer thickness at electrical continuity threshold. On the glass substrate, the gold clusters of different sizes are clearly observed. For later deposition stages, a clear tendency of the gold atoms to aggregate into larger clusters of approximately the same size is observed. At later deposition stages, gold clusters of up to 100 nm in diameter are formed.

Metal-organic chemical vapour deposition of lithium manganese oxide thin films via single solid source precursor

“…It can be observed from the RBS spectra and the obtained areal density value that the film is fairly thick. Expectedly, barring variation in other process parameters, the layer thickness is predictably an increasing function of deposition time [16]. Therefore, to deposit a film with lower thickness, the deposition time should be reduced.…”

A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

“…However, these normal metal coating methods suffer from extreme surface roughness. Considering this fact, chemical vapor deposition (CVD) [27] is an efficient method that offers uniform nanolayer coating with minimal surface roughness. Metal nanoparticles can also be used by maintaining their size during fabrication to obtain a thin and smooth coating surface [26].…”

Ultrathin, Ultrasmooth Gold Layer on Dielectrics without the Use of Additional Metallic Adhesion Layers

“…A reduction of this lower limit for the thickness can be achieved by improving the adhesion between Au and the substrate. The current value for this limit is between 10 and 15 nm [8,9]. The usual approach for adhesion improvement is using Ti or Cr layers.…”