With increasing temperature, the degree of TMI decomposition increases and monomethyl indium (MMI) can form. MMI can undergo polymerization, forming poly-MMI, which has very low volatility. The formation of poly-MMI on the surface is not a self-limiting reaction and thus can continuously absorb In-species on to the surface as long as their concentration permits. Any formation of poly-MMI on the surface in an ALD process will therefore lead to formation of large crystal grains or droplets. At 450 °C, the degree of TMI pyrolysis is even higher and the last In-CH3 bond in MMI can break. This results in elemental In as reported by Jacko et al. and evidenced in our XRD of films deposited at 450 °C by ALD (Fig. ). The reductive environment of the NH3 plasma makes the formation of InN not favored for elemental, zero valent, In as an oxidation to In(III) is needed for formation of InN. Elemental In, on the other hand, can be easily oxidized upon exposure to both residual oxygen in the chamber and ambient after deposition, resulting in the observation of In2O3 in our XRD (Fig. ).