Interpretation of the two-components observed in high resolution X-ray diffraction ω scan peaks for mosaic ZnO thin films grown on c-sapphire substrates using pulsed laser deposition

• Published in: Thin solid films 2011-07, Vol.519 (19), p.6369-6373
• Main Authors: Durand, O., Letoublon, A., Rogers, D.J., Hosseini Teherani, F.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Correlation analysis; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General equipment and techniques; Heteroepitaxy; High resolution; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Misfit dislocations; Mosaics; Nondestructive testing; Physics; Pulsed laser deposition; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Structure of solids and liquids; crystallography; Thin films; Transverse scans; X-ray diffraction and scattering; X-ray scattering; X-ray scattering (including small-angle scattering); X-rays; Zinc oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.04.036

X-ray scattering methods were applied to the study of thin mosaic ZnO layers deposited on c-Al 2O 3 substrates using Pulsed Laser Deposition. High Resolution (HR) studies revealed two components in the ω scans (transverse scans) which were not resolved in conventional “open-detector” ω rocking curves: a narrow, resolution-limited, peak, characteristic of long-range correlation, and a broad peak, attributed to defect-related diffuse-scattering inducing a limited transverse structural correlation length. Thus, for such mosaic films, the conventional ω rocking curve Full Width at Half Maximum linewidth was found to be ill-adapted as an overall figure-of-merit for the structural quality, in that the different contributions were not meaningfully represented. A “Williamson-Hall like” integral breadth (IB) metric for the HR (00.l) transverse-scans was thus developed as a reliable, fast, accurate and robust alternative to the rocking curve linewidth for routine non-destructive testing of such mosaic thin films. For a typical ZnO/c-Al 2O 3 film, the IB method gave a limited structural correlation length of 110 nm ± 9 nm. The results are coherent with a thin film containing misfit dislocations at the film-substrate interface.