Negative differential resistance and magnetotransport in Fe3O4/SiO2/Si heterostructures

The electronic transport and magnetotransport properties of Fe3O4/SiO2/Si heterostructures were investigated with a current source. Negative differential resistance is observed in Fe3O4/SiO2/p-Si heterostructures. The measurement circuit with four electrodes that I+ (I−) and V+ (V−) came into contact with the Fe3O4 (Si) layer introduces an in-plane transport into the heterostructures. By decreasing the temperature, the in-plane conductive channel switches from Fe3O4 to p-Si. However, the in-plane current is still carried by Fe3O4 in Fe3O4/SiO2/n-Si heterostructures. The formation of an accumulation layer in p-Si facilitates conductive channel switching (CCS), while the depletion layer in n-Si hampers the CCS. At 150 K, a magnetic-field-independent magnetoresistance (MR) in Fe3O4/SiO2/p-Si heterostructures manifests the conductive channel in the space charge region of p-Si. A positive MR generated from the increased electronic scattering in a trapezoidal space charge region reshaped by the magnetic field has been detected.