Point defect reduction in MOCVD (Al)GaN by chemical potential control and a comprehensive model of C incorporation in GaN

A theoretical framework that provides a quantitative relationship between point defect formation energies and growth process parameters is presented. It enables systematic point defect reduction by chemical potential control in metalorganic chemical vapor deposition (MOCVD) of III-nitrides. Experime...

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Bibliographic Details
Published inJournal of applied physics Vol. 122; no. 24
Main Authors Reddy, Pramod, Washiyama, Shun, Kaess, Felix, Kirste, Ronny, Mita, Seiji, Collazo, Ramon, Sitar, Zlatko
Format Journal Article
LanguageEnglish
Published Melville American Institute of Physics 28.12.2017
Subjects
Applied physics
Chemical potential
Chemical reactions
Crystal defects
Crystal growth
Density functional theory
Free energy
Gallium nitrides
Heat of formation
Mathematical models
Metalorganic chemical vapor deposition
Organic chemistry
Point defects
Predictions
Process parameters
Reduction
Supersaturation
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Summary:A theoretical framework that provides a quantitative relationship between point defect formation energies and growth process parameters is presented. It enables systematic point defect reduction by chemical potential control in metalorganic chemical vapor deposition (MOCVD) of III-nitrides. Experimental corroboration is provided by a case study of C incorporation in GaN. The theoretical model is shown to be successful in providing quantitative predictions of CN defect incorporation in GaN as a function of growth parameters and provides valuable insights into boundary phases and other impurity chemical reactions. The metal supersaturation is found to be the primary factor in determining the chemical potential of III/N and consequently incorporation or formation of point defects which involves exchange of III or N atoms with the reservoir. The framework is general and may be extended to other defect systems in (Al)GaN. The utility of equilibrium formalism typically employed in density functional theory in predicting defect incorporation in non-equilibrium and high temperature MOCVD growth is confirmed. Furthermore, the proposed theoretical framework may be used to determine optimal growth conditions to achieve minimum compensation within any given constraints such as growth rate, crystal quality, and other practical system limitations.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.5002682