Local spin injectors using GaAs tips under light excitation

Local spin injectors using GaAs tips at the end of transparent cantilevers have been fabricated using a combination of epitaxial growth, etching processes and photolithographic techniques. The tip luminescence polarization is found to be small because of total internal light reflections of the luminescence inside the tip. However, measurements on planar films of similar doping along with a numerical solution of the spin and charge diffusion equations indicate that the injected spin polarization can be as high as 40% with corresponding electronic concentrations at the tip apex of the order of 1014 cm-3.