One of the most important techniques for depositing nitride thin films is chemical vapor deposition (CVD). Given the inertness of dinitrogen, N2, in thermal CVD, the most common CVD precursor for nitrogen is ammonia, NH3. It should be noted that some CVD processes do use N2 as nitrogen precursor, but then rather in the form of a N2-H2 gas mixture as carrier gas, utilizing an extremely small fraction of all N2 molecules in the gas mixture. But the reactivity of NH3 is not properly matched to most metal CVD precursors, seen from the often very high NH3 to metal precursor ratios used; CVD of semiconductor grade AlN and GaN uses NH3 to trimethyl metal ratios of several hundred. From a purely thermodynamic point, NH3 should decompose to N2 and H2, i.e. the reverse of the Haber-Bosch process. A quick decomposition to inert N2 has been used to explain the very high NH3 to metal ratios used in nitride CVD, which is seen from modeling the CVD gas phase chemistry by purely thermodynamic methods. 12 However, this reasoning does not hold if CVD of the group 13 nitrides, AlN, GaN and InN, is compared. InN forms a temperature sensitive crystal lattice which decomposes to metallic