Abstract:

The development of novel magnetotransport devices has raised interest in the spindependent dynamics of electron scattering and relaxation mechanisms in semiconductor/metal interfaces. Spin transport through a semiconductor/metal interface is still one of the most important obstacle in semiconductor-based spintronics. At many semiconductor surfaces the Fermi-level pinning causes a band bending which significantly affects the carrier and spin dynamics. In addition to pure surface effects, contribution to a different spin polarization decay time might be caused by the increased kinetic energy of the electrons in the band bent region. Due to the large penetration depth of light the carrier as well the spin dynamics in the band bent region can not be probed by pure optical methods such as time-resolved Faraday or Kerr rotation or photoluminecence. We investigate the time evolution of the spin polarization by means of time- and spin-resolved two photon photoemission (TR-2PPE) for different surfaces of the GaAs crystal. High surface and energy sensitivity of TR-2PPE make it ideal for studying the spin dynamics in the Scottky-barrier. We will present measurements on the GaAs(001) and GaAs(110) surface and discuss our results with equivalent bulk measurements (TR Faraday rotation) and theoretical studies.
 
 
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