Growth and structural investigations of epitaxial hexagonal YMnO3 thin films deposited on wurtzite GaN(001) substrates

• Published in: Thin solid films Vol. 515; no. 4; pp. 1807 - 1813
• Main Authors: Balasubramanian, K.R., Chang, Kai-Chieh, Mohammad, Feroz A., Porter, Lisa M., Salvador, Paul A., DiMaio, Jeffrey, Davis, Robert F.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05-12-2006; Elsevier Science
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Epitaxy; Exact sciences and technology; Gallium nitride; Heterostructures; Laser ablation; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Other semiconductors; Oxides; Physics; Single-crystal and powder diffraction; Specific materials; Structure of solids and liquids; crystallography; Theory and models of film growth; Transmission electron microscopy; X-ray diffraction; X-ray diffraction and scattering; Yttrium manganese oxide; Transmission electron microscopy; Yttrium manganese oxide; Epitaxy; X-ray diffraction; Oxides; Laser ablation; Gallium nitride; Heterostructures; Gallium nitrides; XRD; Thin films; Unit cell; Mismatch lattice; Aluminium nitrides; Hafnium; Epitaxial layers; Silicon carbides; Pulsed laser deposition; III-V compound; Hexagonal lattices; Manganese oxides; Growth mechanism; Laser ablation technique; Yttrium oxides; III-V semiconductors
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2006.07.001

Epitaxial hexagonal YMnO3 (h-YMnO3) films having sharp (00l) X-ray diffraction peaks were grown above 700 °C in 5 mTorr O2 via pulsed laser deposition both on as-received wurtzite GaN/AlN/6H-SiC(001) (w-GaN) substrates as well as on w-GaN surfaces that were etched in 50% HF solution. High-resolution transmission electron microscopy revealed an interfacial layer between film and the unetched substrate; this layer was absent in those samples wherein an etched substrate was used. However, the substrate treatment did not affect the epitaxial arrangement between the h-YMnO3 film and w-GaN substrate. The epitaxial relationships of the h-YMnO3 films with the w-GaN(001) substrate was determined via X-ray diffraction to be (001)YMnO3‖(001)GaN:[11¯0]YMnO3‖[110]GaN; in other words, the basal planes of the film and the substrate are aligned parallel to one another, as are the most densely packed directions in planes of the film and the substrate. Interestingly, this arrangement has a larger lattice mismatch than if the principal axes of the unit cells were aligned.