Silicon technology has been the driver of electronics for decades and is still the embedded base as researchers look toward next generation electronics with potential gains in power, density, and speed using the spin as well as the charge of the electron, so-called “spintronics”. Nature has provided an ideal tool for studying spin in direct band semiconductors: the optical selection rules for interband transitions near the gap allow optical injection and detection of spin-polarized of electrons with one-to-one correspondence with photon energy. Indeed, much of early spintronics was explored in direct bandgap semiconductors and heterostructures and in the latest generation of 2-d electronic materials—to the exclusion of Silicon which has an indirect bandgap. We have recently observed optical spin-injection in Silicon at the indirect bandgap using spin-polarized light for injection, and muon spin relaxation to observe the degree of spin-polarization. While the degree of spin-polarization is small, we expect it to be ultimately larger and a potential tool for probing and manipulating spin in silicon spintronics and quantum computing.
Harry W. K. Tom, Professor, Physics and Astronomy, University of California, Riverside