Xiu Faxian, Wang Yong, Zou Jin, Wang Kang L
Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California.
Nano Rev. 2011;2. doi: 10.3402/nano.v2i0.5896. Epub 2011 Mar 7.
Electric-field control of ferromagnetism in magnetic semiconductors at room temperature has been actively pursued as one of the important approaches to realize practical spintronics and non-volatile logic devices. While Mn-doped III-V semiconductors were considered as potential candidates for achieving this controllability, the search for an ideal material with high Curie temperature (T(c)>300 K) and controllable ferromagnetism at room temperature has continued for nearly a decade. Among various dilute magnetic semiconductors (DMSs), materials derived from group IV elements such as Si and Ge are the ideal candidates for such materials due to their excellent compatibility with the conventional complementary metal-oxide-semiconductor (CMOS) technology. Here, we review recent reports on the development of high-Curie temperature Mn(0.05)Ge(0.95) quantum dots (QDs) and successfully demonstrate electric-field control of ferromagnetism in the Mn(0.05)Ge(0.95) quantum dots up to 300 K. Upon the application of gate-bias to a metal-oxide-semiconductor (MOS) capacitor, the ferromagnetism of the channel layer (i.e. the Mn(0.05)Ge(0.95) quantum dots) was modulated as a function of the hole concentration. Finally, a theoretical model based upon the formation of magnetic polarons has been proposed to explain the observed field controlled ferromagnetism.
室温下对磁性半导体中铁磁性的电场控制，作为实现实用自旋电子学和非易失性逻辑器件的重要途径之一，一直受到积极探索。虽然锰掺杂的III-V族半导体被认为是实现这种可控性的潜在候选材料，但寻找具有高居里温度（T(c)>300 K）且在室温下具有可控铁磁性的理想材料的工作已经持续了近十年。在各种稀磁半导体（DMS）中，源自硅和锗等IV族元素的材料，由于它们与传统互补金属氧化物半导体（CMOS）技术具有出色的兼容性，是这类材料的理想候选者。在此，我们回顾了关于高居里温度Mn(0.05)Ge(0.95)量子点（QD）发展的近期报道，并成功证明了在高达300 K的温度下，Mn(0.05)Ge(0.95)量子点中铁磁性的电场控制。在向金属氧化物半导体（MOS）电容器施加栅极偏压时，沟道层（即Mn(0.05)Ge(0.95)量子点）的铁磁性会随着空穴浓度的变化而调制。最后，基于磁极化子的形成提出了一个理论模型，以解释所观察到的场控铁磁性。
