Magnetic-field- and bias-sensitive conductivity of a hybrid Fe/SiO2/p-Si structure in planar geometry

Abstract

Pronounced magnetic-field- and bias-sensitive features of the transport properties of a Fe/SiO2/p-Si hybrid structure in planar geometry at temperature variation are investigated. Comparative analysis of two Fe/SiO2/p-Si samples, one with a continuous Fe film and the other with two electrodes formed from a Fe layer and separated by a micron gap, shows that these features are due to the metal-insulator-semiconductor (MIS) transition with a Schottky barrier near the interface between SiO2 and p-Si. Resistance of such a MIS transition depends exponentially on temperature and bias. In the structure with a continuous ferromagnetic film, the competition between conductivities of the MIS transition and the Fe layer results in the effect of current channel switching between the Fe layer and a semiconductor substrate. Within certain limits, this process can be controlled by a bias current and a magnetic field. Positive magnetoresistance of the structures at high temperatures is determined, most likely, by disorder-induced weak localization. In the structure with the gap, negative magnetoresistance is observed at certain temperature and bias. Its occurrence should be attributed to an inversion layer formed in the semiconductor near the SiO2/p-Si interface when MIS transition is in the inversion regime.

Extremely high magnetic-field sensitivity of charge transport in the Mn/SiO2/p-Si hybrid structure

“…First, there is no determined SiO 2 layer between silicon and the metal film and, consequently, determined Mn/SiO 2 and SiO 2 /p-Si interfaces in the structure with the Fe layer, where the SiO 2 layer in crosssectional TEM images was not spread. 17 This can be attributed to stronger diffusion of Mn ions in SiO 2 as compared with diffusion of Fe ions. Second, the Mn film is polycrystalline and inhomogeneous over its entire thickness.…”

“…17 A p-Si(100) wafer with a resistivity of 5 Ω · cm (a doping density (N A ) of 2 × 10 15 cm 3 ) with the (111) orientation was used as a substrate. The substrate thickness (L) was 350 µm.…”

“…In the dc mode, the MR effect is weak even in high magnetic fields of up to 9 T. 17 For this reason, we started studying the Schottky diodes with the Mn electrode with impedance (Z = R ac + iX, where R ac and X are the real and imaginary parts of the impedance, respectively) and magnetoimpedance measurements. At reverse and low forward bias V b (V b < V c b ≈ 2 V), we obtained the results similar to those reported in 18,20 for the structures with Fe.…”

“…Our studies on lateral devices and Schottky diodes based on the Fe/SiO 2 /p(n)-Si hybrid structures showed that the interface states localized in the SiO 2 /p(n)-Si interfacial region make a significant contribution to magnetotransport. [17][18][19][20] These states are involved in recharging and their energy structure is rearranged by a magnetic field. However, this is apparently not the only possible mechanism, since it does not explain the variety of MR effects observed in the MIS-structure-based devices.…”

Two-layer Model of Reflective Ferromagnetic Films in Terms of Magneto-optical Ellipsometry Studies

“…It is well-known that the simplest method of generating a spin-polarised current in a metal is to pass the current through a ferromagnetic material. That is why, one of the perspective materials for spintronics is a ferromagnetic/semiconductor two-layered structure [1].…”