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

Abstract

We report on abrupt changes in dc resistance and impedance of a diode with the Schottky barrier based on the Mn/SiO2/p-Si structure in a magnetic field. It was observed that at low temperatures the dc and ac resistances of the device change by a factor of more than 106 with an increase in a magnetic field to 200 mT. The strong effect of the magnetic field is observed only above the threshold forward bias across the diode. The ratios between ac and dc magnetoresistances can be tuned from almost zero to 108% by varying the bias. To explain the diversity of magnetotransport phenomena observed in the Mn/SiO2/p-Si structure, it is necessary to attract several mechanisms, which possibly work in different regions of the structure. The anomalously strong magnetotransport effects are attributed to the magnetic-field-dependent impact ionization in the bulk of a Si substrate. At the same time, the conditions for this process are specified by structure composition, which, in turn, affects the current through each structure region. The effect of magnetic field attributed to suppression of impact ionization via two mechanisms leads to an increase in the carrier energy required for initiation of impact ionization. The first mechanism is related to displacement of acceptor levels toward higher energies relative to the top of the valence band and the other mechanism is associated with the Lorentz forces affecting carrier trajectories between scatterings events. The estimated contributions of these two mechanisms are similar. The proposed structure is a good candidate for application in CMOS technology-compatible magnetic- and electric-field sensors and switching devices.

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.…”

Magneto-transport phenomena in metal/SiO2/n(p)-Si hybrid structures

“…We studied a number of the M/SiO 2 /n(p)-Si metal-oxide-semiconductor (MOS) structures, where M is ferromagnetic Fe [14], and Fe 3 Si, ferrimagnetic Fe 3 O 4 [15]and even paramagnetic Mn [16]. At the same time, the most interesting results were obtained for the structures with Fe and Mn layers fabricated on the silicon substrates of p-and n-types.…”

“…Regarding the technology of structure fabrication, it didn't differ for cases of p-and n-type of substrates. Below, as an example, we'll describe the technology used for fabrication of the Fe/SiO 2 /p-Si and Mn/SiO 2 /p-Si [15,16]. p-Si(100) wafers with a resistivity of 5  cm (a doping density of 2×10 15 cm -3 ) were used as substrates.…”

“…Figure 1b [16] shows a cross-sectional TEM image of the Mn/SiO 2 /p-Si interfaces. We would like to emphasize some features of this structure.…”

Influence of metal magnetic state and metal-insulator-semiconductor structure composition on magnetoimpedance effect caused by interface states

“…We detected the effect of a magnetic field on the structure properties and the possibility of controlling the magnetoresistance value via the bias voltage [6]. Moreover, we found the value of the magnetoresistance reached 10 8 % [9]. We made assumptions that the main role in these effects is played by surface states at the insulator/semiconductor interface.…”