## 3 Results and Discussion
On the other hand, if one compares the topography in Figure 2i with that of Figure 2c, one can observe that introducing high concentrations of In in Ga\({}_{2}\)O\({}_{3}\) films hinders the growth of large nanocrystallites, leading to the growth of a nanocomposite film formed from smaller nanocrystals with a lower surface film roughness, respectively. As it is shown further, similar effects are observed in Ga\({}_{2}\)O\({}_{3}\) films incorporated by Sn. Detailed data concerning the surface roughness parameters of films imaged in Figure 2 are presented in Table 3.  
The data presented in Table 3 reveal that all values of the Ssk parameter are positive (Ssk \(>\) 0), with few exceptions, which means that there are more peaks and fewer valleys. The kurtosis measures how heavy or light the tails of the statistical distribution are relative to a normal (Gaussian) distribution. It provides insight into the frequency of extreme values (outliers) in the statistical distribution. Exceptions with negative excess kurtosis are for the Zn\({}_{0.4}\)Mg\({}_{0.6}\)O and Ga\({}_{2}\)O\({}_{3}\) films. When excess kurtosis is negative, the distribution has lighter tails and a flatter peak, suggesting that the surface profile is more evenly distributed with fewer extreme values. The Ga\({}_{1.75}\)Al\({}_{0.25}\)O\({}_{3}\) films exhibit the highest maximum peak height (Sp) at 78.30 nm, while the In\({}_{0.24}\)Sn\({}_{0.12}\)O\({}_{0.64}\) films show the lowest value at 18.09 nm. Regarding the average roughness (Sa), the highest value is observed for Ga\({}_{1.75}\)Al\({}_{0.25}\)O\({}_{3}\) at 16.78 nm, followed by Zn\({}_{0.4}\)Mg\({}_{0.6}\)O at 11.40 nm, and the lowest value is found for In\({}_{0.24}\)Sn\({}_{0.12}\)O\({}_{0.64}\) at 3.36 nm. Especially important for practical applications, particularly for microfluidic applications, is the issue of the impact of films topology and composition upon their wettability properties. This issue was addressed by measuring the contact angle on the metal oxide nanostructured surfaces, as described in the Section 2 of the paper. The results of these investigations are summarized in Table 4, and the correlations between the contact angle and the surface roughness for all deposited oxide thin films are analyzed in Figure 5. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Films** & **RMS Roughness** & **Mean Roughness** & **Skew** & **Excess Kurtosis** & **Maximum Peak** \\
**Composition** & **(Sq), nm** & **(Sa), nm** & **(Ssk)** & **Excess Kurtosis** & **Height (Sp), nm** \\ \hline In\({}_{0.24}\)Sn\({}_{0.12}\)O\({}_{0.64}\) & 4.19 & 3.36 & 0.3436 & 0.0193 & 18.09 \\ In\({}_{0.18}\)Sn\({}_{0.04}\)Ga\({}_{0.16}\)O\({}_{0.62}\) & 10.86 & 8.29 & 0.9035 & 2.253 & 68.60 \\ In\({}_{1.0}\)Mg\({}_{0.5}\)O\({}_{2.0}\) & 9.74 & 7.41 & 1.183 & 1.867 & 54.57 \\ In\({}_{0.4}\)Mg\({}_{0.8}\)O\({}_{1.4}\) & 11.29 & 8.80 & 0.5487 & 0.8461 & 58.30 \\ In\({}_{1.75}\)Ga\({}_{0.25}\)O\({}_{3}\) & 5.36 & 4.16 & 0.1041 & 0.7035 & 26.83 \\ In\({}_{1.0}\)Ga\({}_{1.0}\)O\({}_{3}\) & 12.91 & 10.18 & 0.9081 & 0.5102 & 54.76 \\ Zn\({}_{0.8}\)Mg\({}_{0.2}\)O & 11.33 & 8.90 & 0.6512 & 1.105 & 59.86 \\ Zn\({}_{0.4}\)Mg\({}_{0.6}\)O & 12.41 & 11.40 & 0.1266 & \(-\)0.0937 & 38.43 \\ Ga\({}_{2}\)O\({}_{3}\) & 10.71 & 8.58 & 0.0120 & \(-\)0.0677 & 33.80 \\ Ga\({}_{1.75}\)Al\({}_{0.25}\)O\({}_{3}\) & 19.99 & 16.78 & 0.4843 & 0.1903 & 78.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Surface roughness parameters determined from AFM measurements (5 \(\times\) 5 \(\upmu\)m\({}^{2}\)) of samples with the topology shown in Figure 2.  
The analysis of data from Figure 5 suggests that, for most of the material classes (systems), the hydrophobicity of film surfaces increases by increasing their surface roughness. This is true for the Zn\({}_{1-x}\)Mg\({}_{x}\)O, (In\({}_{1-x}\)Ga\({}_{x}\))\({}_{2}\)O\({}_{3}\) and (In\({}_{2}\)O\({}_{3}\))\({}_{1-x}\)(MgO)\({}_{x}\) materials, and in all these materials, the hydrophobicity and the surface roughness increase with the increasing \(x\)-value.