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Quantum Chemical Feasibility Study of Methylamines as Nitrogen Precursors in Chemical Vapor Deposition

The possibility of using methylamines instead of ammonia as a nitrogen precursor for the CVD of nitrides is studied using quantum chemical computations of reaction energies: reaction electronic energy (ฮ”๐‘Ÿ๐ธ๐‘’๐‘™๐‘’๐‘) reaction enthalpy (ฮ”๐‘Ÿ๐ป) and reaction free energy (ฮ”๐‘Ÿ๐บ). The reaction energies were calculated for three types of reactions: Uni- and bimolecular decomposition to more reactive nitrogen species, adduct forming with trimethylgallium (TMG) and trimethylaluminum (TMA) followed by a release of methane or ethane and surface adsorption to gallium nitride for both the unreacted ammonia or methylamines or the decomposition products. The calculations for the reaction entropy and free energy were made at both STP and CVD conditions (300ยฐC-1300ยฐC and 50 mbar). The ab inito Gaussian 4 (G4) theory were used for the calculations of the decomposition and adduct reactions while the surface adsorptions were calculated using the Density Functional Theory method B3LYP. From the reactions energies it can be concluded that the decomposition was facilitated by the increasing number of methyl groups on the nitrogen. The adducts with mono- and dimethylamine were more favorable than ammonia and trimethylamine. ๐‘๐ป2 was found to be most readily to adsorb to ๐บ๐‘Ž๐‘ while the undecomposed ammonia and methylamines was not willingly to adsorb.

Identiferoai:union.ndltd.org:UPSALLA1/oai:DiVA.org:liu-132812
Date January 2015
CreatorsRรถnnby, Karl
PublisherLinkรถpings universitet, Kemi
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeStudent thesis, info:eu-repo/semantics/bachelorThesis, text
Formatapplication/pdf
Rightsinfo:eu-repo/semantics/openAccess

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