(a) (b) The different growth regimes in the C7H8 process can also be observed in the Arrhenius plot displayed in Figure . From the data, there seems to be three growth regimes in the C7H8 process. For T ≤ 1250 ℃, the Arrhenius plot suggests that the growth is kinetically limited with an activation energy of 103 kJ/mol. At 1250 ℃ < T < 1300 ℃, the kinetics-controlled growth seems to retain but with a much higher activation energy. In this temperature range, the preferred growth orientation of 3C-SiC deposited with toluene switches from <111> to <110> direction and free carbon also starts to be incorporated into the films. The change of the slope in the Arrhenius plot and in the preferred growth orientation can be interpreted as an indication of change in the deposition chemistry. It should be noted that a change in deposition chemistry can also result in a change in reaction order, meaning that, e.g. the rate constant in the Arrhenius equation is not the same over the entire investigated temperature range in Figure . 7. When the temperature continues to rise above 1300 ℃, the deposition again alters its character, and the films grow in the form of more flake-like crystals (Figure ). This alteration is represented by a plateau in Figure , suggesting that at T ≥ 1300 °C the deposition chemistry enters the mass-transport limited regime with an apparent activation energy of 5 kJ/mol. On the other hand, the 3C-SiC growth in the CH4 process appears to be kinetics limited with an activation energy of 85 kJ/mol between 1100 ℃ and 1400 ℃ and the preferred growth orientation changes from randomly oriented to highly <110> at T > 1200 ℃. environment with large excess of hydrogen and at elevated temperatures, toluene was reported to undergo two possible decomposition pathways :