Tapping mode atomic force microscopy observation of self-affine fractal roughness in electrochemically roughened silver electrode surfaces

Abstract

We have investigated recrystallization of an electrochemically roughened silver electrode surface in Ar-saturated water, using cyclic voltammetry (CV), Auger electron spectroscopy (AES), and tapping mode atomic force microscopy (TMAFM). Comparison of CVs before and after 92 h relaxation in water indicates that surface flattening occurs at room temperature when the roughened Ag is in contact with water. An AES spectrum of the Ag surface before the relaxation shows that chlorine still remains on the surface, probably in the form of AgCl. We determined the roughness exponents (α) for the roughened Ag surfaces before and after the relaxation from the slopes of the linear regions observed in plots of log (the interface width) vs log (length scale) calculated from TMAFM data. At larger length scales than the average Ag nodule size, αs were 0.50±0.02 and 0.64±0.02 for the roughened surfaces before and after the relaxation, respectively. These results suggest that the scaling theory may be applicable to the recrystallization process at the submicron level.

Roughness exponents and grain shapes

“…If the grain surface is flat, α 1 is very close to 1, while for rounded grains it decreases to values close to 0.85 [13]. These results match those of a large number of experimental works [4][5][6][7][8][9][10]. However, other experimental works show film surfaces with grainy structure, the same crossover in roughness scaling or HHCF, but with much smaller exponents α 1 [14][15][16][17][18][19][20][21][22].…”

“…1 with α ≈ 1, which is explained by the growth models with flat or slightly rounded grains [13]. Among those works, we highlight the study of rf sputtered LiCoO x films by Kleinke et al [5], which gives 0.91 ≤ α 1 ≤ 0.95; the spray pyrolysis growth of ZnO films by Ebothé et al [6], which gives 0.94 ≤ α 1 ≤ 0.97 for high flow rates; the electrodeposition of cooper by Mendez et al [8] and of gold by Vázquez et al [7], which give α 1 = 0.87 ± 0.06 and α 1 = 0.90 ± 0.06, respectively; the electrochemical roughening of silver electrodes by Otsuka and Iwasaki [9], which gives α 1 between 0.95 and 0.98; and the pulsed laser deposition of La modied-P bT iO 3 films of Vasco et al [10], which have α 1 = 1.…”

“…For instance, the presence of grains in the film surface leads to a crossover between two regimes where w increases with r with different roughness exponents, α 1 and α 2 , as illustrated in Fig. 1 [4][5][6][7][8][9][10]. For the HHCF, the same crossover occurs with exponents χ 1 and χ 2 ..…”

Role of substrate on topography features of nickel deposited nanostructures

“…One observes that α is proportional to s with ITO and inversely proportional with Cu while no real classification of this sort can be done with Au. Only two cases: s = 0.33 mV/s with Au and s = 1.67 mV/s with ITO lead to α ≈ 0.40-0.50 characteristic of Kardar-Parisi-Zhang (KPZ) growth mode [33,34]. The results 0.60 ≤ α ≤ 1 obtained with Cu for s = 0.17 and 0.33 mV/s concur with the KPZ stochastic mode including restricted surface diffusion [34], all the other cases related to 0 < α ≤ 0.40 are associated with more complex situations.…”

Modelling of silica film growth by chemical vapour deposition : Influence of the interface properties

“…The relationship between the granular morphology and surface diffusion processes has been reported for different systems [23,24]. This regime is denoted thereafter as the MBE regime.…”