Extended defect structure of a-plane GaN produced by sidewall lateral epitaxial overgrowth

• Published in: Journal of crystal growth 2011-09, Vol.331 (1), p.49-55
• Main Authors: Hu, Yan-Ling, Kraemer, Stefan, Fini, Paul T., Speck, James S.
• Format: Article
• Language: English
• Subjects: A1. Extended defect; A1. Inversion domain; A1. Stacking fault; A3. Hydride vapor phase epitaxy; B1. Gallium nitride; B1. GaN; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal defects; Defects and impurities: doping, implantation, distribution, concentration, etc; Density; Exact sciences and technology; Gallium nitrides; Inversions; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microstructure; Physics; Stacking faults; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Transmission electron microscopy; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2011.03.063

This paper demonstrates the use of Sidewall Lateral Epitaxial Overgrowth (S-LEO) on a-plane GaN thick films on r-plane sapphire by hydride vapor phase epitaxy (HVPE). Comprehensive study of the extended defect microstructure of the a-plane GaN films was carried out using cross-sectional and plan-view transmission electron microscopy (TEM). A very low density of primary threading dislocations and a heterogeneous microstructure can be found in the GaN films. In the window region and N-face wing region, the extended defects included type I 1 and type I 2 basal stacking faults (BSFs), as well as prismatic stacking faults (PSFs) on a-planes. The density of type I 1 BSFs was in the order of ∼2×10 5 cm −1, type I 2 BSFs in the order of ∼10 4 cm −1, and corresponding localized partial dislocation density less than 1.5×10 9 cm −2. PSFs on a-planes were connected to two neighboring type I 1 BSFs with an estimated density of 3×10 2 cm −1 in the plan-view images. In the Ga-face overgrowth regions, the density of BSFs was lower than 10 4 cm −1. However, inversion domains bounded by (1 1̄ 0 2), (1 1̄ 0 2̄), and (1 1̄ 0 0) planes were found in the Ga-face wing regions. The nature of inversion domain boundaries (IDB) on m-planes can be explained by the Auserman-Gehamn model using high-angle annular dark-field TEM images. ► Extended defect structure of novel lateral overgrowth technique for nonpolar GaN including quantification of the density of different types of basal plane stacking faults. ► Observation of prismatic stacking faults in GaN and determination of the nature of the prismatic stacking fault. ► Observation of inversion domains and determination of the atomic structure of the inversion domain boundary.