Enhanced linear magnetoresistance of germanium at room temperature due to surface imperfection

Abstract

We report an enhanced linear magnetoresistance in germanium at room temperature. The magnetic-field dependence shows no saturation at magnetic fields (B) up to 4 T and the magnetoresistance sensitivity at low fields (B < 0.4 T) can reach ∼8 T−1. It is found that this magnetoresistance effect is ascribed to surface imperfection, which cannot only increase the recombination rate but also enhance the inhomogeneity. Our work may be attractive to the magnetic-field sensing industry and make germanium-based magnetoelectronics further developed.

Weak localization and weak antilocalization in doped germanium epilayers

“…This behaviour has been observed in other semiconductor systems 21 and at room temperature in germanium devices. 22 It is shown that magnetoresistance can be linear at even very low fields for systems with a large mobility disorder. This is consistent with the data obtained for the p-type sample, since the low temperature mobility in this device has the relatively small value of 200 cm 2 V À1 s…”

The space charge limited current and huge linear magnetoresistance in silicon

“…1a , a typical I-V curve of an intrinsic N-Si exhibits a slow rise ( V < 10 V ) followed by a sharp, power-law rise at a critical voltage V 0 (black open diamonds). In order to avoid the competition of the surface and bulk parallel paths 18 and the edge effects of a limited-size sample 14 , a symmetric out-of-plane electrode set-up is selected in experiments, as shown in the insert of Fig. 1a .…”

“…χ L can be expressed as γ ln(1 + Δ n/n 0 ) with a fitting coefficient γ . Under a high electric field, the uncompensated charge and the concomitant push-back electrostatic field yield the spatial distribution of polarity-conserved charges 14 , 17 , 18 . The localized charges are polarized along electric field, and the term of polarization convergence ought to be considered even for a non-polar one.…”

“…The magnetoresistance approaches to zero in Ohmic regime, which is exactly consistent with the classical equilibrium magneto-electric transport theory 21 . The turn-on voltage, V 0 , grows quasi linearly, from 14 to 104 V, with the increase of magnetic field from 0 to 1 T. Under a magnetic field, the current suppression constrains the field-induced ionization along the transport direction 13 , 18 , 25 , resulting in the postponed of V 0 . In fact, although such phenomena are reported in those pioneer works for silicon wafers 13 , 15 , 17 , 26 , to our best knowledge qualified explanations have not been achieved.…”

“…The phenomena may originate from a spatial inhomogeneous electric field or an inhomogeneous charge distribution 13 , 14 . Experimentally, the magnetoresistance can be controlled by the current, the magnetic field 15 , the dopant concentration 16 , the electrode configuration 14 , 17 and the difference of the surface/bulk electron combination rate 18 . One could predict a non-saturating huge linear magnetoresistance through a macroscopic random resistor network model 19 , 20 or evaluate the net-charge distributions via finite element calculations 14 , 17 .…”