Characterization of crystallographic properties and defects via X-ray microdiffraction in GaN (0001) layers

• Published in: Physica status solidi. A, Applications and materials science Vol. 203; no. 1; pp. 142 - 148
• Main Authors: Barabash, R. I., Barabash, O. M., Ice, G. E., Roder, C., Figge, S., Einfeldt, S., Hommel, D., Katona, T. M., Speck, J. S., DenBaars, S. P., Davis, R. F.
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.01.2006; WILEY‐VCH Verlag
• Subjects: 61.10.Nz; 68.37.Hk; 68.55.Jk; 68.55.Ln; 68.60.Bs; 81.15.Gh; DISLOCATIONS; GALLIUM NITRIDES; MATERIALS SCIENCE; MICROANALYSIS; ORIENTATION; SILICON CARBIDES; STRAINS; STRESS RELAXATION; THERMAL EXPANSION; X-RAY DIFFRACTION
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.200563503

Intrinsic stresses due to lattice mismatch, high densities of threading dislocations, and extrinsic stresses resulting from the mismatch in the coefficients of thermal expansion, are present in almost all III‐Nitride heterostructures. Stress relaxation in the GaN layers occurs in conventional, cantilever (CE) and in pendeo‐epitaxial (PE) films via the formation of additional misfit dislocations, domain boundaries, elastic strain and wing tilt. Polychromatic X‐ray microdiffraction, high resolution monochromatic X‐ray diffraction and SEM analysis have been used to determine the crystallographic properties, misfit dislocations distribution and crystallographic tilts in uncoalesced GaN layers grown by PE and CE. The crystallographic tilt between the GaN(0001) and Si(111) planes was detected in the CE grown samples on Si(111). In contrast there was no tilt between GaN(0001) and SiC(0001) planes in PE grown samples. The wings are tilted upward for both the PE and CE grown uncoalesced GaN layers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)