Spin diffusion and the role of screening effects in semiconductors

The electron spin properties in semiconductors are of great interest because of their potential in future spin-driven microelectronic devices. We performed simulations on electron spin injection in an n-doped silicon bar from a magnetic semiconductor with spin-dependent conductivity. A variation of doping can introduce charge accumulation/depletion layer at the interface. We found substantial spin transport differences, when spins are introduced through a charge accumulated and a charge depleted interface layer. Special attention is paid to a possible spin injection efficiency enhancement compared to the existing theory at the charge neutrality condition. We found that at a fixed bulk spin polarization, the efficiency increases, if spins are injected from a charge depleted source.