First-principles and thermodynamic analysis of trimethylgallium (TMG) decomposition during MOVPE growth of GaN

• Published in: Journal of crystal growth 2017-06, Vol.468, p.950-953
• Main Authors: Sekiguchi, K., Shirakawa, H., Yamamoto, Y., Araidai, M., Kangawa, Y., Kakimoto, K., Shiraishi, K.
• Format: Article
• Language: English
• Subjects: A1. Computer simulation; A3. Metalorganic vapor phase epitaxy; B1. Gallium compounds; B2. Semiconducting III-V materials; Decomposition; Epitaxial growth; Gallium nitride epitaxy; Gallium nitrides; Mathematical analysis; Metalorganic chemical vapor deposition; MOVPE epitaxy; Thermodynamics; Vapor phase epitaxy
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2016.12.044

We analyzed the decomposition mechanisms of trimethylgallium (TMG) used for the gallium source of GaN fabrication based on first-principles calculations and thermodynamic analysis. We considered two conditions. One condition is under the total pressure of 1atm and the other one is under metal organic vapor phase epitaxy (MOVPE) growth of GaN. Our calculated results show that H2 is indispensable for TMG decomposition under both conditions. In GaN MOVPE, TMG with H2 spontaneously decomposes into Ga(CH3) and Ga(CH3) decomposes into Ga atom gas when temperature is higher than 440K. From these calculations, we confirmed that TMG surely becomes Ga atom gas near the GaN substrate surfaces. •H2 is indispensable for TMG decomposition.•TMG decomposes into Ga atom gas near the GaN growth surfaces.•Ga atoms from TMG adsorb and migrate on the GaN substrate surfaces.