Large magnetoresistance in Si:B-SiO2-Al structures

Abstract

A magnetic-field-dependent resistance change of eight orders of magnitude is observed in boron-doped Si-SiO2-Al structures. In order to identify the elementary mechanisms governing this phenomenon, the thickness of the oxidic layer, which is used as an interface energy barrier, has been varied by changing the exposure time to an oxygen plasma. Next, the chemical composition has been monitored by in situ x-ray photoelectron spectroscopy measurements. From current-voltage measurements, we observe that at low temperatures, an ultrathin SiO2 layer provides the kinetic energy to trigger an autocatalytic process of impact ionization. A magnetic field suppresses the onset of impact ionization to higher electric fields, resulting in a large magnetoresistance.

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“…Although the positive MR phenomenon was also observed in doped silicon,6–9 the transport behaviors and correlated mechanisms between doped silicon and p–n junction are distinctively different. For the doped silicon, the I–V characteristics typically obeyed the Ohm law at the low electric field and the Mott‐Gurney law at high electric field 8, 9.…”

“…Magnetoresistance (MR) effects of non‐magnetic materials such as silver chalcogenide,1, 2 semimetallic bismuth,3 doped InSb,4 GaAs,5 and silicon6–15 have recently attracted a growing amount research interest due to their physical interests and potential applications in magneto‐electronics devices. Compared with the magnetic materials, the MR effect on these non‐magnetic materials presents two distinguished features.…”

“…Among these non‐magnetic materials, silicon provides substantial benefits including the long spin coherence and the compatibility with the current CMOS technology, as well as the ability to fabricate low‐cost devices. However, due to its modest carrier mobility it is experimentally and theoretically still a great challenge to obtain the large MR effect and related mechanism 6–15. One promising approach is based on the tunnel injection through the thin silicon dioxide layer, which triggers a transition to a high mobility transport regime by an autocatalytic process of impact ionization 6.…”

“…One promising approach is based on the tunnel injection through the thin silicon dioxide layer, which triggers a transition to a high mobility transport regime by an autocatalytic process of impact ionization 6. At proper oxidation thicknesses (≈2 nm) the large MR ratios in lighted doped p‐type silicon have been reported at 4 K and even at room temperature 6, 7, 15. An alternative way is to produce a quasi‐neutrality breaking by applying a large electric field in silicon, in which the large MR effect is believed to arise from an electric‐field inhomogeneity due to a space‐charge effect 8, 9.…”

Laser‐Triggered Large Magnetoresistance Change Observed in Corbino Disk of Cu/SiO2/Si

“…Magnetic materials are commonly used in the research of Corbino magnetoresistance . Since the recent discoveries of large geometric magnetoresistance effect in non‐magnetic semiconductors, especially silicon, there has been a technological and fundamental interest in this phenomenon. Theoretically, several models have been proposed to explain the basic mechanism, which generally conclude that the basic cause of the effect is unevenly carrier distribution and the bending of current path .…”