Effect of substrate orientation on the crystal quality and surface roughness of Nb-doped TiO{sub 2} epitaxial films on TiO{sub 2}

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1996.0128· OSTI ID:280132

Gao, Y; Chambers, S A ^[1]

---

1. Environmental Molecular Sciences Laboratory, Pacific Northwest Laboratory, P. O. Box 999, MS K2-12, Richland, Washington 99352 (United States)

We have grown Nb-doped TiO{sub 2} epitaxial films on (100) and (110)-oriented TiO{sub 2} rutile substrates by molecular beam epitaxy. Nb substitutionally incorporates at cation sites in the rutile lattice, forming Nb{sub {ital x}}Ti{sub 1{minus}{ital x}}O{sub 2} solid solutions. However, the crystal quality and surface roughness of the films depend strongly on the substrate orientation. Surface roughening and defect formation occur at lower values of {ital x} on (100) than on (110). This result is due to anisotropic changes in the metal-oxygen bond lengths within the rutile structure in going from TiO{sub 2} to NbO{sub 2}; there are 1{percent} and 12{percent} changes in the metal atom to octahedron-base oxygen and metal atom to octahedron-vertex oxygen bond lengths, respectively. Every metal atom in the (100) growth surface has in-plane components of the 12{percent} mismatch. However, only half of the metal atoms in the (110) growth plane have such components. Thus, there is substantially larger in-plane lattice mismatch when the growth surface is (100) compared to (110), resulting in surface roughening and formation of defects at a lower doping level for (100)-oriented Nb{sub {ital x}}Ti{sub 1{minus}{ital x}}O{sub 2} epitaxial films. {copyright} {ital 1996 Materials Research Society.}

• Research Organization: Pacific Northwest National Laboratory
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 280132
• Journal Information: Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 4 Vol. 11; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL BONDS
CRYSTAL ORIENTATION
CRYSTAL STRUCTURE
DOPED MATERIALS
FILMS
MOLECULAR BEAM EPITAXY
NIOBIUM ADDITIONS
ROUGHNESS
SOLID SOLUTIONS
SUBSTITUTION
SUBSTRATES
TITANIUM OXIDES