Lateral photovoltaic effect and magnetoresistance observed in Co-SiO2-Si metal-oxide-semiconductor structures

We present an investigation on the magnetoresistance (MR) properties and lateral photoeffect (LPE) of thin Co films deposited on Si substrates with a thin native oxide layer. A marked transition on the transport properties of our films was observed around 250 K. The thinnest Co film exhibits the largest MR of 17.5%. We explain the transport and magnetotransport properties by the conducting channel switching from the upper metallic film to the Si inversion layer. Besides the MR, a large lateral photovoltage which depends in a linear way on the incident light spot position measured on the metallic film was also investigated. The largest open-circuit position sensitivity is 27.6 mV mm-1. The LPE was discussed in terms of metal-semiconductor junction