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.
Highlights
Magnetoresistance and magnetoimpedance in various materials and artificial structures attract attention of researches as physical phenomena interesting for both fundamental research and application
It was shown that the ac and dc transport properties of the Schottky diode based on the Mn/SiO2/p-Si structure are highly sensitive to external magnetic fields at low temperatures
The giant MR effect originates from impact ionization initiated in the bulk of the Si substrate when the bias voltage attains a threshold value
Summary
Magnetoresistance and magnetoimpedance in various materials and artificial structures attract attention of researches as physical phenomena interesting for both fundamental research and application. Our studies on lateral devices and Schottky diodes based on the Fe/SiO2/p(n)-Si hybrid structures showed that the interface states localized in the SiO2/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 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. As the bias exceeded a certain critical value, the magnetotransport properties drastically changed: the MR attained giant values of about 106% in the dc and ac modes in magnetic fields below 0.1 T, which cannot be explained by the mechanisms associated with the interface states in the SiO2/p-Si interfacial region and attracted by us previously to ground the dc MR and magnetoimpedance. We found that the key role in the giant MR effect under high bias is played by impact ionization
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