Author

Youngnam Cho

Date of Award

8-2002

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

Advisor

William J. DeSisto

Second Committee Member

M. Clayton Wheeler

Third Committee Member

John C. Hassler

Abstract

Conducting metal oxide thin films are of broad interest because they have a wide variety of magnetic and electronic properties. Materials exist that range from superconducting to insulating, are ferromagnetic and are ferroelectric. These properties make thin conducting oxide films attractive for many industrial applications. A class of metal oxides exists that adapt the rutile crystal structure; the structure of the mineral rutile, TiO2. These metal oxides have the general formula MO2 where M is a metal cation of valence +4. Metal oxides crystallizing in the rutile structure also display a wide variety of physical properties. The objective of this research was to examine the ability of single crystal rutile (TiO2) substrates to stabilize various isostructural MO2 compounds prepared by chemical vapor deposition (CVD). This included metastable and unusual valence state metal oxide compounds. The materials examined in this thesis included CrO2 and RuO2. CrO2 is a ferromagnetic material of significant interest because it has been theoreticcally predicted to have complete spin-polarization of the conduction electrons. This exciting intrinsic property makes CrO2 a leading candidate for breakthrough devices in the field of magnetoelectronics. RuO2 is a highly conductive oxide with metallic properties. It has attracted significant interest in the development of ultralarge scale integrated circuits as a conducting layer combined with new classes of high dielectric oxide materials. In addition, RuO2 is an ideal non-magnetic metal layer (NM) for magnetoelectronic devices based upon CrO2. In order for advances in magnetoelectronics to occur using rutile-based materials, ultra thin multilayer structures must be fabricated with precise thickness and interfacial homogeneity control. A first step in realizing this goal is gaining a fundamental understanding of the thermodynamic processing space for stabilizing each compound. A second step is understanding factors which influence film roughness and physical properties. This thesis attempts to understand some of these major issues for ultimately fabricating novel magnetoelectronic devices based upon metal oxides that crystallize in the rutile structure. The characterization of the films included the crystalline structure by x-ray diffraction and surface morphology by atomic force microscopy.

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