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Deposition of Metal-Doped Oxides for Spintronic Applications


EMSL Project ID
6292

Abstract

For spintronic devices such as spin-FETs, efficient injection of spin-polarized electrons into a semiconductor material is necessary. For devices compatible with current semiconductor technology, efficient spin injection into Si is desired. Diluted magnetic semiconductors (DMSs) that can be grown epitaxially on Si are prime candidates. The epitaxial growth will result in a high-quality interface, reducing depolarization caused by scattering at interfacial defects. Further, the conductivity of the DMS can be tuned by doping to match that of Si, greatly increasing the spin injection efficiency. While most known DMS materials have Curie points well below room temperature, anatase CoxTi1-xO2-x has been shown to have a Curie temperature of at least 700K when deposited on LaAlO3(001). In addition, anatase is well lattice-matched to Si. To prevent interfacial reactions between the film and substrate resulting in SiO2 and/or silicide formation, a buffer layer of epitaxial SrTiO3 (STO) is first deposited. Previous work has shown that when Co:TiO2 is deposited on STO/Si, films with promising magnetic properties are obtained. However, the Co segregates to Co-rich anatase particles on the film surface, making the material impractical for most microelectronic devices. As an alternative, in this study Cr-doped TiO2 and Co-doped STO will be explored in detail to determine their applicability as ferromagnetic spintronic material. The materials and magnetic properties of the thin films will be evaluated by several techniques, including x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), scanning Auger electron spectroscopy (AES), and Rutherford backscattering (RBS), to determine the origin of magnetism. This work may lead to other candidate Co-doped oxide materials.

Project Details

Project type
Exploratory Research
Start Date
2003-12-09
End Date
2006-01-11
Status
Closed

Team

Principal Investigator

Tiffany Kaspar
Institution
Pacific Northwest National Laboratory

Team Members

David McCready
Institution
Pacific Northwest National Laboratory

Vaithiyalingam Shutthanandan
Institution
Environmental Molecular Sciences Laboratory

Chongmin Wang
Institution
Environmental Molecular Sciences Laboratory

Theva Thevuthasan
Institution
Environmental Molecular Sciences Laboratory

Scott Chambers
Institution
Pacific Northwest National Laboratory

Timothy Droubay
Institution
Pacific Northwest National Laboratory

Scott Lea
Institution
Environmental Molecular Sciences Laboratory