Photovoltage effects under sinusoidal illumination

A theory is presented for open-circuit voltage (PV) and short-circuit current (SI) effects when a p-n junction diode is illuminated through a slit with a sinusoidal pattern moving across it. The amplitude of PV oscillations is strongly reduced due to annihilation of photocarriers diffusing to the metal contacts on the surface so as to keep the voltage beneath the contacts constant. From the dependence of the oscillation amplitude on the wave vector of the illumination pattern, the lateral diffusion length of the photocarriers can be deduced. The short-circuit currents under sinusoidal and uniform illumination are equal. A combination of PV and SI measurements should reveal anisotropy in the diffusivities of photocarriers in the plane of the diode and perpendicular to it. Recent results on quantum well diodes are discussed. © 1999 American Institute of Physics.