Linear magnetoresistance in commercial n-type silicon due to inhomogeneous doping

TL;DR

This paper reports large linear magnetoresistance in commercial n-type silicon, explained by inhomogeneous doping and current-jetting effects, challenging traditional resistivity models.

Contribution

It demonstrates that inhomogeneous doping causes linear magnetoresistance in silicon, with potential amplification through sample aspect ratio adjustments.

Findings

Linear magnetoresistance observed in commercial n-type silicon.

Magnetoresistance increased from 445% to 4707% by altering sample aspect ratio.

Classical model of spatially fluctuating donor densities explains the phenomenon.

Abstract

Free electron theory tells us that resistivity is independent of magnetic field. In fact, most observations match the semiclassical prediction of a magnetoresistance that is quadratic at low fields before saturating. However, a non-saturating linear magnetoresistance has been observed in exotic semiconductors such as silver chalcogenides, lightly-doped InSb, N-doped InAs, MnAs-GaAs composites, PrFeAsO, and epitaxial graphene. Here we report the observation of a large linear magnetoresistance in the ohmic regime in commonplace commercial n-type silicon wafer. It is well-described by a classical model of spatially fluctuating donor densities, and may be amplified by altering the aspect ratio of the sample to enhance current-jetting: increasing the width tenfold increased the magnetoresistance at 8 T from 445 % to 4707 % at 35 K. This physical picture may well offer insights into the large magnetoresistances recently observed in n-type and p-type Si in the non-ohmic regime.