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Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride

revised on 18.01.2019, 08:20 and posted on 21.01.2019, 13:42 by Karl Rönnby, Sydney C. Buttera, Polla Rouf, Sean Barry, Lars Ojamäe, Henrik Pedersen
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 use 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 shows 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, instead micrometer sized gallium droplets were deposited. This study shows that the nitrogen surface chemistry is most likely more important to consider than the gas phase chemistry when searching for better nitrogen precursors for 13-N CVD.


This project was founded by the Swedish foundation for Strategic Research through the project “Time-resolved low temperature CVD for III-nitrides” (SSF-RMA 15-0018). STB and SCB acknowledge the Vinnova VINNMER Marie Curie incoming mobility program for funding for a sabbatical and research visits to Linköping University (Vinnova grant 2015-03714). HP and STB are very grateful for the networking support provided from the COST Action MP1402 'Hooking together European research in atomic layer deposition (HERALD) supported by COST (European Cooperation in Science and Technology). LO acknowledges financial support from the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU No. 2009 00971).


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