High quality AlGaN grown on ELO AlN/sapphire templates

• Published in: Journal of crystal growth 2013-08, Vol.377, p.32-36
• Main Authors: Zeimer, U., Kueller, V., Knauer, A., Mogilatenko, A., Weyers, M., Kneissl, M.
• Format: Article
• Language: English
• Subjects: A1. Characterization; A1. Defects; A3. Epitaxial lateral overgrowth; A3. Metalorganic chemical vapor deposition; Aluminum; Aluminum nitride; Applied sciences; B1. AlGaN; B3. Light emitting diodes; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal growth; Defects and impurities in crystals; microstructure; Density; Electronics; Epitaxial growth; Etching; Exact sciences and technology; Homogeneity; Linear defects: dislocations, disclinations; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optoelectronic devices; Physics; Sapphire; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Structure of solids and liquids; crystallography
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2013.04.041

The defect structure and the homogeneity of 1–3µm thick AlxGa1−xN layers grown on epitaxially laterally overgrown (ELO) AlN on patterned AlN/sapphire templates have been investigated in dependence on the miscut direction of the c-plane sapphire substrates, the etching depth into the sapphire and the Al concentration. It was found that shallowly etched AlN/sapphire templates with a 0.25° miscut toward the a-plane provide a smooth surface of ELO AlN and therefore a good Al homogeneity in the overgrown Al0.8Ga0.2N layer. The threading dislocation density in these layers is as low as 5×108cm−2. •Miscut and etch depth of AlN/sapphire templates play an important role for surface morphology and TDD of thick ELO AlN.•Surface steps on ELO AlN give rise to periodic Al inhomogeneities in subsequently grown AlxGa1−xN.•Conditions for growth of high quality AlxGa1−xN layers on ELO AlN could be identified.•Al0.8Ga0.2N with a homogeneous Al distribution and a TDD as low as 4.5×108cm−3 was obtained.