Synthesis of highly luminescent, undoped, Mg-doped and Si-doped GaN powders

• Published in: Journal of crystal growth Vol. 304; no. 1; pp. 225 - 232
• Main Authors: Garcia, Rafael, Bell, Abigail, Thomas, Alan C., Ponce, Fernando A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2007; Elsevier
• Subjects: A1. Microcrystals; B1. GaN; B2. Phosphors; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Other luminescence and radiative recombination; Physics; 78.55.Cr; B1. GaN; B2. Phosphors; A1. Microcrystals; 78.60.Hk; 81.20.Ka; 81.10.Fq; 81.05.Ea; Crystal growth; Gallium nitrides; Magnesium alloys; Doping; Luminescence; Gallium alloys; Crystallites; Hexagonal crystals; Blood platelets; Optical properties; Arsenic additions; Magnesium additions; Optoelectronics; Optoelectronic properties; Quartz; Silicon additions; Ammonia; Silicon oxides; Wurtzite structure; Microcrystal; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2007.01.033

High-quality doped and undoped GaN crystallites have been grown by reacting high-purity Ga–NH 3 solutions and Ga alloys (Ga–Mg and Ga–Si) with ultra-high-purity ammonia in a horizontal quartz tube reactor at temperatures between 1000 and 1200 °C. An initial low-temperature treatment to dissolve ammonia into the Ga melt produces GaN powders with 100% reaction efficiency. The optoelectronic properties of these materials are comparable or superior to the best thin epitaxial films. Doping was achieved by dissolving doping impurities, such as silicon and magnesium, into the liquid metal. The powders synthesized by this method consist mostly of two differently shaped crystallites: large columns with lengths of around 20 μm and small platelets with diameter between 1 and 3 μm. All these crystallites have the hexagonal wurtzite structure and all exhibit strong room-temperature luminescence with the characteristic GaN-band-edge as well as silicon- and magnesium-related emissions. These characteristics make these materials strong candidates for optoelectronic applications.