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Setup for photocurrent measurements. Fringe is formed in Franz–Keldysh geometry. The fringe spacing is larger than the thickness of the active layer in the PRQW. The polarization of the two writing beams is perpendicular to the external electric field.
Current vs applied dc electric field for various uniform illuminations. The various curves represent the relation between current , electric field , and intensity at a position in the device where intensity is uniform. The inset illustrates the reading of minimum and maximum electric field from a measured current in a PRQW where intensities near maximum and minimum are assumed to be uniform. As shown in the inset, the intersections of a horizontal line corresponding to the measured current under the interference light fringes with and curves gives and , respectively.
Electric field inside PRQW as a function of the applied electric field. and are the maximum and minimum electric fields and is the range of electric field in PRQW. The inset shows electric field variation between and assuming a sinusoidal field.
Change in space-charge electric field with intensity for a fixed applied electric field. and are the maximum and minimum electric fields and is the range of electric field in PRQW. The solid line is an exponential fit shown here as an aid to the eye.
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