Current transport and thermoelectric properties of very high power factor Fe3O4/SiO2/p-type Si(001) devices

Abstract

The current transport and thermoelectric properties of Fe3O4/SiO2/p-type Si(001) heterostructures with Fe3O4 thicknesses of 150, 200, and 350 nm have been investigated between 100 and 300K. We observe a sharp drop of the in-plane resistivity at 200K due to the onset of conduction along the Si/SiO2 interface related to tunneling of electrons from the Fe3O4 into the accumulation layer of holes at the Si/SiO2 interface, whose existence was confirmed by capacitance-voltage measurements and a two band analysis of the Hall effect. This is accompanied by a large increase of the Seebeck coefficient reaching +1000 µV/K at 300K that is related to holes in the p-type Si(001) and gives a power factor of 70 mW/K²m when the Fe3O4 layer thickness is reduced down to 150 nm. We show that most of the current flows in the Fe3O4 layer at 300K, while the Fe3O4/SiO2/p-type Si(001) heterostructures behave like tunneling p-n junctions in the transverse direction. ABSTRACT FROM AUTHOR]

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