In situ optical monitoring of the decomposition of GaN thin films

• Published in: Journal of crystal growth Vol. 203; no. 1; pp. 12 - 17
• Main Authors: Rebey, A, Boufaden, T, El Jani, B
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-1999; Elsevier
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; GaN; Laser reflectometry; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; MOVPE; Physics; Thermal decomposition; Vapor phase epitaxy; growth from vapor phase; 82.60.Cx; GaN; Thermal decomposition; 81.15.Gh; MOVPE; Laser reflectometry; 81.05.Ea; Real time systems; Inorganic compounds; Gallium nitrides; Process control; Controlled atmospheres; Binary compounds; Crystal growth from vapors; Experimental study; Laser beams; Precursor; Thin films; MOVPE method; Reflectometry; Thermodynamic analysis; Kinetics; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(99)00081-0

The GaN thermal decomposition versus the annealing ambient (H
2, N
2+H
2, H
2+NH
3), is investigated in an atmospheric pressure metalorganic vapour phase reactor. The GaN decomposition rate, measured using laser reflectometry, was found to be dependent on the substrate temperature and the flow rate of H
2. A high thermal unstability of GaN in the presence of H
2 gas at 1050°C, is shown. The introduction of nitrogen N
2 blocks partially the decomposition of GaN. Also, we investigated the GaN decomposition at various temperatures in H
2. Two regimes are clearly identified; below 830°C with an activation energy of 1.87
eV and over 830°C with an activation energy of 0.38
eV. Finally, results are analysed using thermodynamic calculation based on the minimisation of the Gibbs energy of the system.