Step-flow growth of ZnO(0 0 0 1) on GaN(0 0 0 1) by metalorganic chemical vapor epitaxy

• Published in: Journal of crystal growth Vol. 310; no. 15; pp. 3407 - 3412
• Main Authors: Ive, T., Ben-Yaacov, T., Van de Walle, C.G., Mishra, U.K., DenBaars, S.P., Speck, J.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.07.2008; Elsevier
• Subjects: A1. Crystal morphology; A1. Crystal structure; A1. High resolution X-ray diffraction; A3. Metalorganic chemical vapor deposition; B1. Oxides; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; 78.66.Hf; B1. Oxides; A1. Crystal structure; A3. Metalorganic chemical vapor deposition; 81.15.Gh; 68.55.Jk; A1. High resolution X-ray diffraction; A1. Crystal morphology; 87.64.Dz; Buffer layer; Stacking faults; 68.55.Jk;78.66.Hf;81.15.Gh;87.64.Dz;Al. Crystal morphology;A1. Crystal structure;A1. High resolution X-ray diffraction;A3. Metalorganic chemical vapor deposition;B1. Oxides; Epitaxial layers; Epitaxy; Organometallic compounds; Thick films; Reciprocal lattice; Template reaction; Screw dislocations; MOCVD; Gallium nitride; Hexagonal lattices; Edge dislocations; Transmission electron microscopy; Growth mechanism; Zinc oxide; III-V semiconductors; Crystal structure
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2008.04.032

We studied the properties of 500–900 nm thick ZnO(0 0 0 1) layers grown by metalorganic chemical vapor deposition on GaN(0 0 0 1) templates. A two-step growth process was employed where a buffer layer was first grown at 350 – 400 ∘ C . The temperature was then ramped up to 750 – 950 ∘ C for the growth of the epitaxial layer. Atomic force micrographs over a 20 × 20 μ m 2 area revealed locally straight steps, indicating step-flow growth. The root-mean-square roughness was less than 2.6 nm. Hexagonal pits were also observed with a pit density of 7.5 × 10 5 – 2.1 × 10 8 cm - 2 . The full width at half maximums of ω -scans across the symmetric (0 0 0 2) and the ( 2 0 2 ¯ 1 ) reflections were as narrow as 0 . 091 ∘ and 0 . 159 ∘ , respectively. Reciprocal space maps showed that the ZnO films were fully relaxed. Transmission electron microscopy revealed that the defects were mainly of mixed or pure edge dislocation type. No pure screw dislocations or stacking faults were observed.