Investigation of Spin Injection in Semiconductors: Theory and Experiment

Citation

Ichiriu, Stephan Robert (2005) Investigation of Spin Injection in Semiconductors: Theory and Experiment. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9CS-0V34. https://resolver.caltech.edu/CaltechETD:etd-05262005-130824

Abstract

Spin electronics, or spintronics, is a nascent field of research whereby the spin degree of freedom in electronic devices is exercised. The electroluminescence polarization of the spin light emitting diode (spin-LED) is important in the characterization of spin injection efficiency into non-magnetic semiconductors. The validity of these measurements is questioned due to the use of large external magnetic fields during measurement and the effects of reflection and refraction within the semiconductor structure. A Monte Carlo ray-tracing simulation for the spin-LED was written to address these issues and a device-dependent polarization correction factor was calculated for the Fe/AlGaAs system to account for these effects. Spin injection into AlGaAs from Fe and Co-Cr spin aligning contacts via a Schottky barrier was measured. Fe was chosen because of the strong spin polarization of conduction electrons at the Fermi level, while Co-Cr was selected because of its properties as a perpendicular magnet for certain alloy concentrations. The contacts were epitaxially grown at room temperature by electron-beam evaporation. These samples were measured to have zero spin injection. The results were attributed to the Schottky barrier properties.

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