The effects of surface treatments of the substrates on high-quality GaN crystal growth

• Published in: Journal of crystal growth Vol. 372; pp. 73 - 77
• Main Authors: Fujimori, Taku, Maruyama, Mihoko, Honjo, Masatomo, Takazawa, Hideo, Murakami, Kosuke, Imabayashi, Hiroki, Todoroki, Yuma, Matsuo, Daisuke, Imade, Mamoru, Yoshimura, Masashi, Mori, Yusuke
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2013; Elsevier
• Subjects: A1. Defects; A1. Substrates; A1. Surface processes; A2. Growth from solution; A3. Liquid phase epitaxy; B1. Nitrides; Cross-disciplinary physics: materials science; rheology; Crystal growth; Crystals; Dislocation density; Epitaxial growth; Exact sciences and technology; Flux; Gallium nitrides; Growth from melts; zone melting and refining; Growth from solutions; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Mechanical polishing; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Surface treatment; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; A3. Liquid phase epitaxy; A2. Growth from solution; A1. Surface processes; B1. Nitrides; A1. Substrates; A1. Defects; Crystal growth; LPE; Gallium; Epitaxial layers; Surface treatments; Etching; Gallium nitride; Crystal perfection; III-V compound; Dislocation density; Surface effect; Growth mechanism; Free-standing film; Crystal faces; Chemical mechanical polishing; Growth from solution; Crystal growth from melts; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2013.03.005

To study the effects of the surface treatments of c-plane GaN substrates on epitaxial growth, surfaces of c-plane GaN freestanding substrates grown by the Na flux method were treated in different ways: mechanical polishing (MP); chemical mechanical polishing after MP; or wet etching (WE) with the use of pyrophosphoric acid after MP. After each surface treatment, we grew Ga-face GaN substrates. Consequently, we concluded that the surface treatment by WE was one of the effective and easy ways to make a Ga-face GaN suitable for growth. Using the WE treatment, we successfully reduced the dislocation density of Ga-face GaN crystal from 2.4×107cm−2 to 3.9×103cm−2, after two times repeated growth. •Effects of the surface treatment of GaN substrates on epitaxial growth were investigated.•Mechanical polishing, chemical mechanical polishing, and wet etching with pyrophosphoric acid.•Wet etching with pyrophosphoric acid was the best of the three surface treatment ways.