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.