X-ray microdiffraction imaging investigations of wing tilt in epitaxially overgrown GaN

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2006-05, Vol.203 (7), p.1733-1738
• Main Authors: Lübbert, D., Mikulík, Petr, Pernot, Petra, Helfen, Lukas, Craven, Michael D., Keller, Stacia, DenBaars, Steven, Baumbach, Tilo
• Format: Article
• Language: English
• Subjects: 61.10.Nz; 68.55.Jk; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 1862-6300; 0031-8965; 1862-6319
• DOI: 10.1002/pssa.200565251

The crystalline quality in epitaxially laterally overgrown (ELO) GaN and the amount of wing tilt is characterized on a local basis, with high spatial and angular resolution. A method of full‐field X‐ray microdiffraction imaging, termed rocking curve imaging, is used to record simultaneously a large set of local X‐ray diffraction profiles originating from sample surface areas of micrometer size. x –ω maps of diffracted intensity allow to quantify the amount of wing tilt in individual lateral ELO periods as well as to monitor the fluctuations of tilt between adjacent periods. Automated shape analysis of the full set of local rocking curves provides a means to quantitatively characterize the local crystalline perfection of GaN. The ELO window and wing regions can be clearly separated; comparison indicates an average improvement of crystal quality by a factor 3–4 due to the lateral overgrowth process. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)