Large positive magnetoresistive effect in silicon induced by the space-charge effect
Large positive magnetoresistive effect in silicon induced by the space-charge effect
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DOI：
10.1038/nature07711
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发表时间：
2009-02-26
期刊：
影响因子：
64.8
通讯作者：
Kobayashi, Kensuke
中科院分区：
文献类型：
--
作者：
Delmo, Michael P.;Yamamoto, Shinpei;Kobayashi, Kensuke
最近在非磁性半导体（1-8）中发现的大磁阻效应引起了人们的广泛关注，因为这种效应的大小与磁性系统（9-14）中的磁阻效应相当，甚至更大。掺杂半导体中的传统磁阻被直接解释为洛伦兹力对载流子运动的影响（15），但报道的异常大的影响意味着潜在的机制尚未被充分探索。在这里，我们报告了一个简单的设备，基于两个金属接触之间的轻掺杂硅衬底，在室温（300 K）下显示出大于1,000%的大的正磁阻，在25 K下为10,000%，磁场在0和3 T之间。将高电场施加到器件，使得传导受到空间电荷限制（16-18）。对于电荷载流子密度低于10（13）cm（-3）的衬底，磁阻在3 T和9 T之间表现出对磁场的线性依赖性。我们建议，所观察到的大的磁阻可以解释由准中性打破的空间电荷效应，其中不充足的电荷是存在的，以补偿注入到设备中的电子。这引入了电场不均匀性，类似于在其他半导体中观察到的大的非饱和磁阻的情况（1- 5，19）。在这种状态下，电子的运动变得相关，因此变得依赖于磁场。尽管在金属-半导体混合器件中已经实现了室温下的大的正磁阻（6-8），但是我们现在已经以更简单的结构并且以不同于其他已知磁阻效应的方式实现了它（9- 14，20）。它可以用来开发新的硅磁性器件，这可能会进一步推进硅技术。
Recent discoveries of large magnetoresistance in non-magnetic semiconductors(1-8) have gained much attention because the size of the effect is comparable to, or even larger than, that of magnetoresistance in magnetic systems(9-14). Conventional magnetoresistance in doped semiconductors is straightforwardly explained as the effect of the Lorentz force on the carrier motion(15), but the reported unusually large effects imply that the underlying mechanisms have not yet been fully explored. Here we report that a simple device, based on a lightly doped silicon substrate between two metallic contacts, shows a large positive magnetoresistance of more than 1,000 per cent at room temperature (300 K) and 10,000 per cent at 25 K, for magnetic fields between 0 and 3 T. A high electric field is applied to the device, so that conduction is space-charge limited(16-18). For substrates with a charge carrier density below similar to 10(13) cm(-3), the magnetoresistance exhibits a linear dependence on the magnetic field between 3 and 9 T. We propose that the observed large magnetoresistance can be explained by quasi-neutrality breaking of the space-charge effect, where insufficient charge is present to compensate the electrons injected into the device. This introduces an electric field inhomogeneity, analogous to the situation in other semiconductors in which a large, non-saturating magnetoresistance was observed(1-5,19). In this regime, the motions of electrons become correlated, and thus become dependent on magnetic field. Although large positive magnetoresistance at room temperature has been achieved in metal-semiconductor hybrid devices(6-8), we have now realized it in a simpler structure and in a way different from other known magnetoresistive effects(9-14,20). It could be used to develop new magnetic devices from silicon, which may further advance silicon technology.