Scanning Kerr Microscopy of the Spin Hall Effect in <Emphasis Type="Italic">n</Emphasis>-Doped GaAs with Various Doping Concentration

We investigated the doping concentration (N _D) dependence of the extrinsic spin Hall effect (SHE) in n-doped GaAs with N _D raging from 3×10¹⁶ cm⁻³ to 5×10¹⁷ cm⁻³. By using scanning Kerr microscopy (SKM) measurements, we observed the Kerr rotation signal due to the spin accumulation near the channel edges in all the samples with different N _D. Moreover, the position and in-plane magnetic field dependence of the Kerr rotation signal are found to vary with N _D. We analyzed the N _D dependence of the spin Hall conductivity by taking account of the N _D-dependent spin lifetime based on the typical drift-diffusion model.