Creating Spin Currents in Silicon
Abstract
The electronics industry to date has relied upon the control of charge flow, combined with size scaling (i.e., reducing the physical size of elements such as transistors), to continuously increase the performance of existing electronics. This trend, widely known as Moore's Law, has been remarkably successful. However, size scaling cannot continue indefinitely as atomic length scales are reached (the "Moore's Law Roadblock"), so new approaches must be developed. Basic research efforts at NRL and elsewhere have shown that spin angular momentum, another fundamental property of the electron, can be used to store and process information in solid-state devices. Subsequently, the International Technology Roadmap for Semiconductors has identified the electron's spin as a new state variable that should be explored for processing information in the fundamentally new ways that will be required beyond the ultimate scaling limits of silicon-based complementary metal-oxide-semiconductor (CMOS) technology. This approach is known as semiconductor spintronics. Electrical injection and transport of spin-polarized carriers is prerequisite for developing such an approach. To create spin-polarized carriers in silicon, we electrically inject them from a ferromagnetic metal contact, which naturally has more electrons with spin oriented in a particular direction determined by the magnetization ("spin-up" or "majority spin") than in the opposite direction ("spin-down" or "minority spin"). The spin polarization in a typical ferromagnetic metal is approx. 45%. A thin layer of aluminum oxide between an iron contact and the silicon serves as a tunnel barrier to facilitate spin injection by controlling the series resistance and preventing interaction between the iron and the silicon.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2008
- Accession Number
- ADA517999
Entities
People
- A. T. Hanbicki
- Berend T Jonker
- C. H. Li
- G. Kioseoglou
- P. E. Thompson
Organizations
- United States Naval Research Laboratory