POWER DEPENDENT EFFECTS IN THE LUMINESCENCE DECAY OF GAAS/ELECTROLYTE CONTACTS AT THE FLAT BAND POTENTIAL

Saturation of surface traps has been observed in the GaAs/Na2S photoelectrochemical system under modest excitation conditions. Saturation is shown to result in a surface minority trapping velocity that is dependent on time as well as laser excitation power. These saturation effects are observed by studying the luminescence decays of GaAs as a function of excitation pulse power under potentiostatic control at the flat band potential. The decays also indicate that surface minority carrier trapping is fast compared with processes which remove minority carriers from trap states. These results suggest that time-resolved experiments under high injection open circuit conditions may underestimate the surface minority trapping rate under typical solar conditions.