Frequency-dependent magnetotransport phenomena in a hybrid Fe/SiO2/p-Si structure

Abstract

We report the large magnetoimpedance effect in a hybrid Fe/SiO2/p-Si structure with the Schottky barrier. The pronounced effect of magnetic field on the real and imaginary parts of the impedance has been found at temperatures 25–100 K in two relatively narrow frequency ranges around 1 kHz and 100 MHz. The observed frequency-dependent magnetotransport effect is related to the presence of localized “magnetic” states near the SiO2/p-Si interface. In these states, two different recharging processes with different relaxation times are implemented. One process is capture-emission of carriers that involves the interface levels and the valence band; the other is the electron tunneling between the ferromagnetic electrode and the interface states through SiO2 potential barrier. In the first case, the applied magnetic field shifts energy levels of the surface states relative to the valence band, which changes recharging characteristic times. In the second case, the magnetic field governs the spin-dependent tunneling of carriers through the potential barrier. The “magnetic” interface states originate, most likely, from the formation of the centers that contain Fe ions, which can easily diffuse through the SiO2 layer.

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

“…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.…”

The bias-controlled giant magnetoimpedance effect caused by the interface states in a metal-insulator-semiconductor structure with the Schottky barrier

“…17 Previously, we reported the unusual magnetotransport properties of simple devices based on the Fe/SiO 2 /p-Si hybrid structure on a p-type semiconductor substrate. [18][19][20] We investigated the magnetoimpedance, but the value of the effect was much smaller. In addition, due to the features of the spectrum of the interface states at the SiO 2 /p-Si interface, we failed to explicitly separate and analyze the contribution of the magnetosensitive centers to the magnetoimpedance.…”

Spin-dependent electrical hole extraction from low doped p-Si via the interface states in a Fe3Si/p-Si structure

“…To study the Fe 3 Si/Si interface electric properties, a diode was fabricated with an ohmic contact on the substrate backside ( figure 3(d)), for which the measurements of I-V characteristics were performed as well as the temperature and frequency dependences of the real (Re |Z|) and imaginary (Im |Z|) parts of impedance. Studies of charge transport were performed at a cryogenic probe station Lakeshore EMPX-HF 2 and a homebuilt facility based on a helium cryostat and electromagnet [41,42] using a Keithley 2634b SourceMeter and Agilent E4980A for dc and ac measurements, respectively, in the temperature range from 4.2 K to 300 K.…”