Compared to EG, GL has an extra OH group that increases the bridging between the polymer chains in the film and this also improves the stability of the film. Nanoindentation experiments showed also that GL based titanicones have much higher elastic modulus and higher hardness compared to EG based titanicones. Annealing experiments indicated a higher thermal stability for GL based titanicones as well . Ti(DMA)4 is another Ti based inorganic precursor that was investigated as an alternative to TiCl4 as the titanium precursor. Ti(DMA)4 was combined with EG and GL to deposit titanicone films in a temperature range from 80 °C to 160 °C on an Si substrate with 100 nm thermal oxide. In situ ellipsometry revealed for EG based titanicones that the growth initiates but terminates after only 5 to 10 cycles, while for GL based titanicones the growth proceeds and films have a GPC 0.9 Å to 0.2 Å as the temperature increases. This is due to the double reaction phenomenon, which for EG removes both the reactive hydroxyl groups (OH) required to couple with the Ti precursor, while even with a double reaction, GL has a third OH group available to couple to the Ti(DMA)4 precursor in the next cycle. Ti(DMA)4 inorganic precursor is well known and widely used in ALD for the deposition of TiO2 and TiN films by the thermal and plasma enhanced processes. Fumaric acid (FC) is another alcohol organic precursor that was used to deposit titanicone films using TiCl4 on an Si substrate in a temperature range of 180 °C to 350 °C. A temperature-dependent growth characteristic was observed with the growth rate decreasing from 1.10 Å/cycle at 180 °C to 0.49 Å at 300 °C. This reduction can be attributed to the increased thermal motion and desorption of molecules on the growth surface. FTIR spectra indicated that the hybrid film shows a stable bridging bonding mode between Ti and the acid group at temperatures under 200°C and a high bridging/bidentate mixed bonding mode at temperatures over 250°C and 300 °C. Many studies show that the desired properties and the target thickness of a metalcone MLD film are not actually achieved. To help understand this, first principles density functional theory (DFT) calculations have been employed to explore the reaction mechanism and energetics and the role of the organic precursors on the growth of hybrid films. [38] DFT studies show that the aliphatic diol precursors, namely EG and GL, when combined with TMA, undergo double reactions, binding with the surface fragments through the two terminal -OH groups, and this phenomenon reduces the number of active sites and terminates the surface growth. However, DFT results also show that this scheme depends on the metal precursor and the surface as the same aliphatic precursors behave differently when combined with Mg(Cp)2; EG still prefers to orient in a flat configuration and react twice with the surface, while GL prefers to lie in an upright configuration. This yields thicker GL-based magnesicone films, consistent with the experimental observations. DFT studies and experimental work show that aromatic organics can be a better option for the growth of thicker, more flexible but more stable hybrid films. This because aromatic molecules, due to their stiff backbone prefer to orient in a vertical orientation and avoid the double reactions. [41] Such hybrid films are known as "metal-organic" films. These also offer the advantage of allowing the facile tuning of the properties of the organic component through ring functionalisation, without impacting on the stability of the resulting films.