Comparative Study of the Lateral Photovoltaic Effect in Fe 3 O 4 /SiO 2 / n -Si and Fe 3 O 4 /SiO 2 / p -Si Structures

The results of a comparative study of the lateral photovoltaic effect in Fe3O4/SiO2/n-Si and Fe3O4/SiO2/p-Si structures are presented. The lateral photovoltage reaches its maximum near the measurement contacts in both structures, but the signs of this voltage differ. As the light spot moves away from the contacts, the photovoltage varies linearly in Fe3O4/SiO2/n-Si and decreases exponentially in Fe3O4/SiO2/p-Si. It is found that interface states at the SiO2/Si interface induce the photovoltage polarity inversion associated with a change in the conductivity type of silicon. An extreme thickness dependence of the photovoltage with an optimum Fe3O4 film thickness of ~50 nm is observed in both structures.