The properties of aluminum nitride (AlN), including a wide bandgap (6.2 eV), high dielectric constant (k ∼ 9), high electrical resistivity (ρ ∼ 10 11 -10 13 Ω cm), and high thermal conductivity (2.85 W/K cm) 1 make it an important material in microelectronics and optoelectronics. AlN is also used in microelectromechanical systems (MEMS devices) due to its piezoelectric properties. Amorphous AlN finds uses e.g., as passivation and dielectric layers. Thin films of AlN are routinely deposited by reactive sputtering , chemical vapor deposition (CVD) , reactive molecular beam epitaxy (MBE) , and atomic layer deposition (ALD). ALD of AlN has garnered significant attention for applications demanding robust protective layers, such as the development of corrosion-resistant, insulating and protective coatings. ALD is based on sequential, self-limiting surface chemical reactions, enabled by carefully tuned deposition chemistry and an alternating precursor supply onto the substrate. This leads to the hallmark of ALD: conformal deposition on topologically complex surfaces. The alternating surface chemistry also facilitates studies of the surface chemistry and reaction mechanisms as the surface is only exposed to one type of precursor molecule at a time. Puurunen et al. have explored the surface chemistry of AlN using trimethylaluminum (TMA) and ammonia (NH3) by infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy on porous silica and alumina. They found that the amount of hydrogen in amino (-NHx) groups increased with the number of reaction cycles on both alumina (Al2O3) and silica (SiO2) substrates, suggesting that more NHx groups were formed on the Al2O3 and SiO2 surfaces as the reactions progressed. The interaction of TMA with dehydroxylated SiO2 involved ligand exchange with surface hydroxyl (-OH) groups and dissociation in siloxane (-Si-O-Si-) bridges, leading to surface saturation with methyl (CH3) groups, followed by the replacement of these CH3 groups by NHx groups upon reaction with NH3, indicating a stepwise transformation of the surface chemistry. Additionally, upon reacting with silica, TMA generated -Si-CH3 groups on the surface, and the subsequent interaction with NH3, particularly at higher temperatures, led to the removal of over 90 % of the initial CH3 groups, which aligned with the proposed reaction pathway for this process.