Energy-resolved electron-spin dynamics at surfaces of p-doped GaAs
  Electron-spin relaxation at different surfaces of p-doped GaAs is investigated by means of spin, time and energy resolved 2-photon photoemission. These results are contrasted with bulk results obtained by time-resolved Faraday rotation measurements as well as calculations of the Bir-Aronov-Pikus spin-flip mechanism. Due to the reduced hole density in the band bending region at the (100) surface the spin-relaxation time increases over two orders of magnitude towards lower energies. At the flat-band (011) surface a constant spin relaxation time in agreement with our measurements and calculations for bulk GaAs is obtained. 
H. C. Schneider (1), J.-P. Wuestenberg (1), O. Andreyev (1), K.   Hiebbner (1), L. Guo (1), J. Lange (1), L. Schreiber (2), ...