Epitaxial and polycrystalline growth of AlN by high temperature CVD: Experimental results and simulation

AlN growth by HTCVD (High Temperature Chemical Vapor Deposition) from AlCl3 and NH3 is currently a promising way to obtain thick, compact layers of aluminum nitride. This study focused on the development of a kinetic mechanism that models AlN growth with only 7 gas-phase reactions and 4 surface reactions. Ab initio estimation of the thermodynamic data of the AlCl2NH2, AlClNH, AlCl(NH2)2 and Al(NH2)3 intermediates suspected to be involved in the gas-phase reactions is proposed. It was found that only AlCl2NH2 is present in noticeable concentrations under our experimental conditions. Experiments made at different temperatures and N/Al ratios, carried out in a cold wall HTCVD reactor, were used to validate the proposed model. Finally, the N/Al ratio in the gas phase was observed to play a key role in the AlN surface quality. Possible explanations of this influence and future experiments that will confirm this trend are discussed.