Extraordinary magnetoresistance: sensing the future
Extraordinary magnetoresistance: sensing the future
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DOI：
10.2478/s11534-012-0015-1
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发表时间：
2012-06-01
影响因子：
--
通讯作者：
Kusmartsev, Feodor V.
中科院分区：
文献类型：
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作者：
Hewett, Thomas H.;Kusmartsev, Feodor V.
利用有限元法（FEM）的模拟已经产生，以调查方面的圆形异常磁阻（EMR）设备。研究了三个具体特征对所得磁阻的影响：金属与半导体电导率之比（σ（M）/σ（S））;半导体迁移率;以及在半导体与金属界面处引入中间区域以模拟接触电阻。为了获得大的EMR效应，要求电导率比（sigma（M）/sigma（S））大于两个数量级;低于该临界值，所得到的磁阻效应显著降低。对于给定的磁场（低于饱和），大迁移率半导体表现出更大的电磁辐射值，并减少产生磁电阻饱和所需的磁场。这是由于在给定的磁场下产生较大的霍尔角，并且与EMR效应的机制一致。由于实际的磁场传感器需要在低磁场下工作，因此在生产更灵敏的EMR传感器时需要高迁移率半导体。肖特基势垒在半导体-金属界面处的形成已被建模为在半导体-金属界面处引入接触电阻。增加接触电阻的值被发现，以减少EMR的影响，它完全消失的大值。这已经通过观察系统中的电流流动明确地示出，并且与EMR效应的机制一致。界面电阻被用来拟合模拟模型，以现有的实验数据。最佳拟合出现在电阻率为1.55x10（-4）m（高估）的界面。EMR效应在磁场传感器的未来应用方面具有巨大的潜力。任何此类器件的设计都应结合高迁移率材料（如石墨烯）沿着本文中提出的特定功能，以生产有效的磁场传感器。
Simulations utilising the finite element method (FEM) have been produced in order to investigate aspects of circular extraordinary magnetoresistance (EMR) devices. The effect of three specific features on the resultant magnetoresistance were investigated: the ratio of the metallic to semiconducting conductivities (sigma (M) /sigma (S) ); the semiconductor mobility; and the introduction of an intermediate region at the semiconductormetal interface in order to simulate a contact resistance. In order to obtain a large EMR effect the conductivity ratio (sigma (M) /sigma (S) ) is required to be larger than two orders of magnitude; below this critical value the resultant magnetoresistance effect is dramatically reduced. Large mobility semiconductors exhibit larger EMR values for a given field (below saturation) and reduce the magnetic field required to produce saturation of the magnetoresistance. This is due to a larger Hall angle produced at a given magnetic field and is consistent with the mechanism of the EMR effect. Since practical magnetic field sensors are required to operate at low magnetic fields, high mobility semiconductors are required in the production of more sensitive EMR sensors. The formation of a Schottky barrier at the semiconductor-metal interface has been modelled with the introduction of a contact resistance at the semiconductor-metal interface. Increasing values of contact resistance are found to reduce the EMR effect with it disappearing altogether for large values. This has been shown explicitly by looking at the current flow in the system and is consistent with the mechanism of the EMR effect. The interface resistance was used to fit the simulated model to existing experimental data. The best fit occurred with an interface with resistivity of 1.55x10(-4) m (overestimate). The EMR effect holds great potential with regard to its future application to magnetic field sensors. The design of any such devices should incorporate high mobility materials (such as graphene) along with the specific features presented in this paper in order to produce effective magnetic field sensors.