Non-ohmic spin transport in n-type doped silicon*

In contrast with undoped silicon transport layers [1], conduction-band bending in n-type doped silicon spintronic devices results in non-ohmic spin-polarized electron transport [2]: for low applied voltage drops across the transport layer, a potential well causes confinement of electrons in the silicon transport layer, and they must diffuse against an electric field to escape. Numerical simulation using a Monte Carlo algorithm reveals that the average transit time across our 3.3 um Si layer can be changed over 4 orders of magnitude by varying an applied voltage. We can therefore deduce a long spin lifetime [3] in n-type doped silicon from comparison between experimental data and fitting-parameter-free simulation results in spite of the short transport distance. References [1] Ian Appelbaum et al. Nature 447, 295 (2007). [2] H.-Jae. Jang et al. Phys. Rev. B 78, 165329 (2008). [3] Biqin Huang et al. Phys. Rev. Lett. 99, 177209 (2007).