Either way, the presence of pyrolytic carbon indicates a change in the growth chemistry, which could be the cause of the change in crystalline orientation and morphology as seen in SEM and XRD. Interestingly, no signs of pyrolytic carbon can be found in the coatings grown from CH4, even at high temperatures. A possible explanation is the different decomposition products of the hydrocarbons. Toluene will decompose into larger hydrocarbons that may more easily form condensed deposits, while CH4 will only break down into even smaller radicals, which are less prone to form condensed pyrolytic carbon deposits.