## 2 Computational Details
### Substrate Preparation  
As detailed in [PERSON] et al. and [PERSON] et al. [8; 9], the initial alumina surface model was made by annealing an alumina model after randomly replacing Al atom. The ALD of Al\({}_{2}\)O\({}_{3}\) was carried out on a hydroxylated Al\({}_{2}\)O\({}_{3}\) surface. A bulk Al\({}_{2}\)O\({}_{3}\) sample with 770-atoms was generated according to the Al\({}_{2}\)O\({}_{3}\) crystal structure 15.3836208, 20.5114944 and 25.639368 A with equal angles, \(\alpha=\beta=\gamma=55.282635^{\circ}\). The simulation box was then anisotropically scaled to produce a large cubic supercell with the simulation box lengths of a = b = c = 26 A, see Figure 2.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element** & \(q\)**(e)** & **A(Å)** & **B(Å)** & **C(Å\({}^{3}\) kJ\({}^{1/2}\) mol\({}^{-1/2}\))** \\ \hline Al & 1.4175 & 0.78520 & 0.03400 & 36.82 \\ O & \(-\)0.9450 & 1.82150 & 0.13800 & 90.61 \\ H & 0.4725 & \(-\)0.17607 & \(-\)0.02462 & 1.86285 \\ \hline \hline \end{tabular}
\end{table}
Table 1: DFT the inter-atomic potentials [9].  
Figure 2: Al\({}_{2}\)O\({}_{3}\) crystal structure with hydroxylated surface, atoms are red—aluminum, blue—oxygen and yellow—hydrogen, the simulation box lengths of a = b = c = 26 Å.  
Following the rules of the ALD process and relaxation processes in MD simulations, this study also considered that the ALD reactions occur only on the surface's active -OH groups. It is assumed that the products of the metal precursor pulse are fully hydroxylated. Lastly, it was assumed that there are no impurities from the metal precursors left in the ALD films. The reverse reactions are negligible and fit with the algorithm approximately describes the stochastic deposition process [8; 9].  
ALD deposition rule was used in this study as described by [PERSON] et al. A monolayer was built as shown in Figure 3a-e. The simulation box was resized to produce the necessary oxide density after annealing the sample at 5000 K for 300 ps. The sample was then quenched at a rate of 47 K/ps to 300 K in 100 ps. The box was then duplicated twice in the \(x\) and \(y\) directions (to increase the system size), and the surface was formed by expanding the box length in the \(z\)-direction to 51.0 A. To produce the appropriate H content, specified H atoms were injected above the frozen layers to generate a hydroxylated surface. An Al atom was chosen randomly and swapped with an H atom to add to the system. Simultaneously, an O atom was chosen randomly and removed to maintain the system's overall charge neutrality. Finally, the surface was annealed for 500 ps at 1000 K. After annealing, the H atoms migrated to the surface region, resulting in a -OH terminated surface. The migration of -OH groups on the surface increases the ALD growth rate, allowing the surface to accommodate more precursor molecules to react on the surface [8; 9]. The atoms in the bottom 3 A of the simulation box were frozen at their relaxed geometries for additional simulation studies [8; 27]. At that point, it is assumed that the projectile flux to the surface is sufficiently low; the sample surface can be assumed to be in equilibrium before the next hit. Since it is assumed that the duration between incoming projectiles is long enough not to affect each other, the same sample can be utilized for all simulations in this situation. This approximation can produce valuable results only if the model is in thermal equilibrium and a steady-state concerning layer growth [28].  
Figure 3: (a) After minimization (**b**) Annealing at 5000 K for 300 ps. (c) Quenched 300 K for 100 ps (d) Annealed at 1000 K for 500 ps (e) Relaxed hydroxylated surface at 300 K for 100 ps.