Spin injection and detection in semiconductors - Electrical issues and device aspects

Spin selectivity has already been demonstrated for both injection and (recently) detection contacts on semiconductors, but a clear demonstration of a magnetoresistance signal is still lacking. After outlining the various categories of device proposals and the associated choice of semiconductor material, we summarize the various injection contact technologies that have been reported and assess their potential for practical device applications in terms of electrical efficiency, bias dependence (both intrinsic and extrinsic), and performance in unipolar devices. We then focus on the design of an all-electrical injection-detection device in GaAs and demonstrate that a correct design of the semiconductor channel and contact regions is the key for preserving the spin sensitivity that is provided by the contacts.