Low-temperature conducting channel switching in hybrid Fe3O4/SiO2/n-Si structures

• Conducting channel switching between the polycrystalline Fe3O4 film and the n-Si substrate takes place in the Fe3O4/SiO2/n-Si structure at temperature below 125 K.
• This effect occurs via the field-assisted tunneling through the composite insulating layer that consists of the highly resistive Fe3O4 and the tunnel SiO2.
• The switching is attended by a change in the shape of the current-voltage characteristics from the linear at 300 K to the S-type at 80 K.

The carrier transport properties of the polycrystalline magnetite (Fe3O4) films grown on an n-type Si substrate with 5 nm-thick SiO2 have been investigated between 80 and 300 K in current-in-plane geometry. It was established that at temperature decrease to about 120 K, the resistivity of thin Fe3O4 films increases up to a peak value and then abruptly drops. This process is attended by a change in the shape of the current-voltage characteristics from the linear at 300 K to the S-type at 80 K. The observed peculiarities are explained by conducting channel switching from the Fe3O4 film to the Si substrate via the field-assisted tunneling of carriers through the composite insulating layer consisting of highly resistive Fe3O4 and tunnel SiO2.