Electrical and optical spin injection in ferromagnet/semiconductor heterostructures

Spin-based electronics or ‘spintronics’ is a rapidly expanding research area that offers the promise of surpassing the limits of conventional electrical charge-based semiconductor devices with potential advantages in speed and power consumption. For electron spin to be successfully employed in a spintronic device, the integration of electron charge and electron spin in a semiconductor is one of the central issues. In the basic concept of a spintronic device at present, the device functionality relies primarily on three different key processes: spin injection, spin manipulation and spin detection in ferromagnet/semiconductor heterostructures. This article reviews the current status of research on spin injection in semiconductors by both electrical and optical means and discusses the electron spin transport processes across the interface based on optical spin orientation.