Detection and study of photo-generated spin currents in nonmagnetic semiconductor materials

The longitudinal current in Si-doped gallium arsenide was spin-polarized using circularly polarized light. The spin current was detected by the extraordinary Hall effect. An enhancement of Hall conductivity with increasing moderately Si-doping was found, indicating that the introduction of dopants increases the electronic spin polarization. This finding may provide an opportunity for controlling and manipulating nonmagnetic semiconductors via electron spin for operating device applications. Band energy calculations using pseudopotentials confirm the influence of Si content and electron-phonon interaction on the behaviour of the spin current and hence on the spin-dependent Hall voltage.