LASER-BEAM INTERFERENCE EFFECTS ON THE PHOTOVOLTAGE OF A P-N-JUNCTIONDIODE

The photovoltage developed by a p-n junction diode illuminated by an i nterference pattern through a slit depends both on the distance betwee n fringes and the phase of the interference pattern relative to the po sition of the slit. For a slit width which accommodates an integer num ber N of fringes, the voltage is independent of the phase of the patte rn but this is no longer the case for a noninteger number of fringes. The maximum dependence is observed for N + 1/2 fringes within the slit but the effect decreases as N increases. When the fringe distance is no longer negligible compared to the minority carrier diffusion length the dependence of the photovoltage on the number of fringes becomes m ore pronounced. A theory is presented which shows how the diffusion le ngth can be obtained from the experimental data. Experiments on GaAs a nd Si diodes are reported. (C) 1996 American Institute of Physics.