OPTICAL ELECTROMODULATION OF SURFACE-INTRINSIC-DOPED STRUCTURES

The modulation of the electric field within the intrinsic layer of sur face-intrinsic-doped structures by means of a chopped pump beam and in the presence of a constant probe beam is calculated by considering th e modulation of the surface voltage by the photoactivated majority car rier flow. The analysis is focused as to determine the dependency on t he probe and pump photocurrents and on the chopping frequency of the o bserved rise and fall transient time constants of the time resolved ph otoreflectance signal. The non linear features of the carrier dynamics are worked out in detail. A rescaling of the time constants by the po wer of the probe beam is predicted. (C) 1997 American Institute of Phy sics.