## 3 Results  
Figure 2 represents the SEM images of the samples with graphene before and after five ALD cycles of TMA and H\({}_{2}\)O. The typical morphology of a single polycrystalline graphene layer on Si/SiO\({}_{2}\) surface presented in Figure 2 (left panel) and the small grains of the deposited Al\({}_{2}\)O\({}_{3}\) on graphene edges and in defect places are clearly recognizable in Figure 2 (right panel) and the amount of Al on those samples is very low (Table 1). The thickness of the five cycles of Al\({}_{2}\)O\({}_{3}\), estimated by XRR, is 3.6 A and the density 1.21 (g/cm\({}^{3}\)), which indicates the emergence of a very sparse material layer but can still be a model by XRR. The thickness of graphene on Si/SiO\({}_{2}\) substrate was 0.6 nm. Figure 1: Nanoindentation tip calibration results for reduced modulus (y axis on the left) and hardness (y axis on the right) as data points compared to the reference values 69.6 and 9.25 GPa, respectively, from the quartz glass presented with horizontal lines. The x axis indicates the depth of the measurement—the displacement of the tip. The displacement region where the measured values match with the properties of the fused quartz glass can be regarded as a trustworthy range. After a deposition of five cycles Al\({}_{2}\)O\({}_{3}\) the main bands of graphene had the same average positions values (the difference was less than 1 cm\({}^{-1}\)) as compared to the pristine graphene. On the other hand, the G-band broadened up to 15% and the 2D-band up to 10% and the intensity ratio of D- and G-band increased up to 25% (Table 2) as compared to pristine graphene. The broadening of the bands after the ALD process may also be associated with doping [20], or correlated with higher amplitudes of charge fluctuations [22] or be caused by nanometer-scale strain variations [23]. In the case of five cycles of Al\({}_{2}\)O\({}_{3}\) layer coated graphene, the G-band was well decomposed into three bands noted X, G and D' (Figure 3 inset). A similar splitting of the G-band \begin{table}
\begin{tabular}{c c c c c} \hline
**EDX Spectrum** & **C** & **O** & **Al** & **Si** \\ \hline Si/SiO\({}_{2}\)/G & 1.69 & 33.19 & 0.0 & 65.12 \\ Si/SiO\({}_{2}\)/G/Al\({}_{2}\)O\({}_{3}\) & 1.05 & 55.96 & 0.49 & 42.50 \\ \hline \end{tabular}
\end{table} 
Table 1: Elemental composition of samples made (wt%) as determined by EDX analysis. (All elements analyzed (normalized) and all result in weight%). Figure 3: Raman spectra of Si/SiO\({}_{2}\)/G (red line) and Si/SiO\({}_{2}\)/G/Al\({}_{2}\)O\({}_{3}\) (black line) structures. Normalized by G-band according to G-band intensities. Inset: Raman spectra fitting (in accord with Lorentz function) in the range from 1300 to 1700 cm\({}^{-1}\) for G-band after Al\({}_{2}\)O\({}_{3}\) deposition process. has been reported in the case when graphene was transferred onto the thicker (20-30 nm) HfO\({}_{2}\) coated Si/SiO\({}_{2}\) substrates [24]. The averaged elastic modulus and hardness of the substrate without graphene (Si/SiO\({}_{2}\)) and the modulus covered with the single polycrystalline graphene layer (Si/SiO\({}_{2}\)/G) are presented in Figure 4. At higher displacements (190 nm) the difference in Young's modulus in these areas was up to 20%, yet only 6% for hardness. The averaged elastic modulus of the substrate without graphene was around 74.1 with a standard deviation of 0.1 GPa and hardness 9.0 (0.1) GPa. This resembles closely to the calibration standard, which was also amorphous SiO\({}_{2}\) (Figure 1). The substrate with a graphene possessed an averaged modulus of 93 (1) and hardness of 9.5 (0.1) GPa at a tip displacement of 190 nm. Five ALD cycles of Al\({}_{2}\)O\({}_{3}\) increased the elastic modulus and hardness of the sample (not shown) and the thin Al\({}_{2}\)O\({}_{3}\) layer induced a rise of modulus with a displacement up to 110 GPa. Hardness was increased to 10 GPa. However, the differences between the samples with and without graphene diminished.