The influence of the surface on charge carrier transport in GaAs films

Contactless transient photoconductivity measurements in n-doped GaAs films with different doping concentrations are presented. It is shown that at low excess carrier densities the signal is due to excess charge carriers separ ated in the space charge region. These signals are characterized by a long decay time not related to the bulk properties of the films. At moderate exc ess carrier densities surface recombination takes place still hampered by t he space charge field giving way to a high surface recombination at high ex citation densities. (C) 2001 Elsevier Science B.V, All rights reserved.