POWER DEPENDENT EFFECTS IN PHOTOLUMINESCENCE VS VOLTAGE SCANS OF GAAS/ELECTROLYTE JUNCTIONS USING PICOSECOND PULSE EXCITATION

Photoluminescence from n-GaAs has been measured as a function of applied voltage under excitation with a picosecond laser at three excitation power levels. A large increase in the photoluminescence intensity at the flat band potential is observed as the excitation power is increased. Analysis of the data with the modified dead layer model shows that the surface minority trapping velocity decreases as the laser power is increased. We attribute this to a saturation of surface minority carrier traps resulting from picosecond pulse excitation and compare the results with a companion study in which surface minority trapping velocities at the flat band potential are determined from luminescence decay profiles.