Status and perspectives of the ammonothermal growth of GaN substrates

• Published in: Journal of crystal growth Vol. 310; no. 5; pp. 876 - 880
• Main Authors: Hashimoto, Tadao, Wu, Feng, Saito, Makoto, Fujito, Kenji, Speck, James S., Nakamura, Shuji
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2008; Elsevier
• Subjects: A2. Growth from solutions; A2. Single-crystal growth; B1. Nitrides; B1. Semiconducting gallium compounds; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities in crystals; microstructure; Exact sciences and technology; Growth from solutions; Linear defects: dislocations, disclinations; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Structure of solids and liquids; crystallography; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; 82.33.De; B1. Nitrides; A2. Single-crystal growth; A2. Growth from solutions; 81.05.Ea; 81.10.Dn; B1. Semiconducting gallium compounds; Crystal growth; Gallium; Polycrystals; Crystal seeds; XRD; Chemical etching; Gallium nitride; Dislocation density; Interfaces; A2. Growth from solutions; A2. Single-crystal growth; Bl. Nitrides; Bl. Semiconducting gallium compounds; Monocrystals; Transmission electron microscopy; Threading dislocation; Growth mechanism; Crystal growth from solutions; Gallium compounds; Defect formation; Growth from solution; 82.33.De; 81.05.Ea; 81.10.Dn; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2007.11.088

The seeded growth of GaN by the ammonothermal method is updated. By using a polycrystalline GaN nutrient together with higher concentration of NaNH 2, we have attained a long-term ammonothermal growth to 90 days. The as-grown crystal showed an improved structural quality to the previously reported GaN bulk crystals grown by the seeded ammonothermal growth, demonstrating the feasibility of the ammonothermal method for a high-quality bulk GaN growth. The threading dislocation density estimated by plan-view transmission electron microscopy (TEM) observations was <1×10 6 cm −2 for the Ga-face and 1×10 7 cm −2 for the N-face. There was no dislocation generation observed at the interface on the Ga-face although a few dislocations were generated at the interface on the N-face. The chemical etching together with X-ray diffraction measurements revealed macroscopic grains in the grown crystals.