Study of the epitaxial–lateral-overgrowth (ELO) process for GaN on sapphire

• Published in: Journal of crystal growth Vol. 195; no. 1; pp. 333 - 339
• Main Authors: Yu, Zhonghai, Johnson, M.A.L., Brown, J.D., El-Masry, N.A., Cook Jr, J.W., Schetzina, J.F.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.1998; Elsevier
• Subjects: Applied sciences; Cathodoluminescence, ionoluminescence; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition technology; Electronics; Epitaxial lateral overgrowth; Exact sciences and technology; Gallium nitride; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microelectronic fabrication (materials and surfaces technology); MOVPE; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other luminescence and radiative recombination; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Vapor phase epitaxy; growth from vapor phase; Epitaxial lateral overgrowth; MOVPE; 81.15; Gallium nitride; 81.05; Inorganic compounds; Gallium nitrides; Epitaxy; Binary compounds; Crystal growth from vapors; Cathodoluminescence; Experimental study; Spatial variation; Lateral growth; Crystal perfection; Characterization; Dislocation density; Monocrystals; Lateral epitaxial overgrowth; MOVPE method; Growth mechanism; Masking; Overlayers; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(98)00638-1

Growth of GaN by MOVPE on mismatched substrates such as sapphire and SiC produces a columnar material consisting of many hexagonal grains ∼0.2–1.0 μm in diameter. However, the epitaxial–lateral-overgrowth (ELO) process for GaN creates a new material – single-crystal GaN. We have studied the ELO process using a MOVPE reactor featuring vertical gas flows and fast substrate rotation to synthesize GaN ELO samples. Characterization experiments consisted of plan-view scanning electron microscopy and vertical-cross-section transmission electron microscopy studies, which disclosed a large reduction in dislocations in the ELO regions of the GaN samples. Panchromatic and monochromatic cathodoluminescence images and spectra were employed to study the spatial variation of the optical properties of the GaN ELO samples.