Spin Relaxation in Germanium Nanowires

Abstract: We use semiclassical Monte Carlo approach along with spin density matrix calculations to model spin polarized electron transport. The model is applied to germanium nanowires and germanium two dimensional channels to study and compare spin relaxation between them. Spin dephasing in germanium occurs because of Rashba Spin Orbit Interaction (structural inversion asymmetry) which gives rise to D'yakonov-Perel(DP) relaxation. In germanium spin flip scattering due to Elliot-Yafet(EY) mechanism also leads to spin relaxation. The spin relaxation tests for both 1-D and 2-D channels are carried out at different values of temperature and driving electric field and the variation in spin relaxation length is recorded. Spin relaxation length in a nanowire is found to be much higher than that in a 2-D channel due to suppression of DP relaxation in a nanowire. At lower temperatures the spin relaxation length increases. This suggests that spin relaxation in germanium occurs slowly in a 1-D channel (nanowires) and at lower temperatures. The electric field dependence of spin relaxation length was found to be very weak.