A mass spectrometric survey scan was carried out to see the residual reaction species and byproducts leaving the reactor (Fig. ). The main residual gases from the ALD reactor are H2, N, CH4, NH3, Ar, N2 and Al(CH3), while CH3 and C2H6 are detected as minor species. No other species were detected beyond m/z = 60. From these species, CH4 is neither a molecule delivered into the reactor nor a direct fragment of the dosed molecules (TMA and NH3) but is expected to be a product of surface chemical reactions. Hence, we studied and monitored its evolution with temperature over time as illustrated in Fig. . It can be noted that the signal from m/z = 16 increases rapidly with the NH3 pulse for both the thermal and the plasma process. As the temperature increases, the m/z = 16 signal is also detected with the TMA pulse. From the slope of the tangent of the decay of the m/z = 16 signal, in Fig. , we extracted an approximation for the rate constants for the methane evolution from the surface reactions. By doing this for all three studied temperatures, we could approximate the activation energies (Ea) for the methane evolution, using Arrhenius plots shown in supporting information Fig. . The extracted activation energies for methane evolution were 19-20 kJmol -1 during the TMA pulse, 14 kJmol -1 during the plasma activated NH3 pulse, and 17 kJmol -1 during the thermally activated NH3 pulse. The shape of the Arrhenius plots suggests that the NH3 pulses are in a mass transport limited regime at T ≥ 300 °C, while the TMA pulses seem to be in a surface kinetics limited regime at all temperatures studied.