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Summary: Phil. Trans. R. Soc. A (2011) 369, 35543574
doi:10.1098/rsta.2011.0137
REVIEW
Introduction to spin-polarized ballistic hot
electron injection and detection in silicon
BY IAN APPELBAUM*
Department of Physics, Center for Nanophysics and Advanced Materials,
University of Maryland, College Park, MD 20742, USA
Ballistic hot electron transport overcomes the well-known problems of conductivity and
spin lifetime mismatch that plague spin injection attempts in semiconductors using
ferromagnetic ohmic contacts. Through the spin dependence of the mean free path in
ferromagnetic thin films, it also provides a means for spin detection after transport.
Experimental results using these techniques (consisting of spin precession and spin-valve
measurements) with silicon-based devices reveals the exceptionally long spin lifetime
and high spin coherence induced by drift-dominated transport in the semiconductor.
An appropriate quantitative model that accurately simulates the device characteristics
for both undoped and doped spin transport channels is described; it can be used to
recover the transit-time distribution from precession measurements and determine the
spin current velocity, diffusion constant and spin lifetime, constituting a spin `Haynes
Shockley' experiment without time-of-flight techniques. A perspective on the future of
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