Chemical vapor deposition (CVD) is one of the most important techniques for depositing thin films of the group 13 nitrides (13-Ns), AlN, GaN, InN, and their alloys, for electronic device applications. The standard CVD chemistry for 13-Ns uses ammonia as the nitrogen precursor; however, this gives an inefficient CVD chemistry, forcing N/13 ratios of 100/1 or more. Here, we investigate the hypothesis that replacing the N-H bonds in ammonia with weaker N-C bonds in methylamines will permit better CVD chemistry, allowing lower CVD temperatures and an improved N/13 ratio. Quantum chemical computations show that while the methylamines have a more reactive gas-phase chemistry, ammonia has a more reactive surface chemistry. CVD experiments using methylamines failed to deposit a continuous film, while instead micrometer-sized gallium droplets were deposited. This study shows that the nitrogen surface chemistry is most likely more important to be considered than the gas-phase chemistry when searching for better nitrogen precursors for 13-N CVD.
The Journal of Physical Chemistry Part C
Department of Chemistry

Rönnby, K. (Karl), Buttera, S.C. (Sydney C.), Rouf, P. (Polla), Barry, S.T, Ojamäe, L. (Lars), & Pedersen, H. (Henrik). (2019). Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride. The Journal of Physical Chemistry Part C. doi:10.1021/acs.jpcc.9b00482