Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA.
ACS Nano. 2012 Jun 26;6(6):5710-7. doi: 10.1021/nn301956m. Epub 2012 Jun 11.
To explore spintronics applications for Ge nanowire heterostructures formed by thermal annealing, it is critical to develop a ferromagnetic germanide with high Curie temperature and take advantage of the high-quality interface between Ge and the formed ferromagnetic germanide. In this work, we report, for the first time, the formation and characterization of Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire transistors, in which the room-temperature ferromagnetic germanide was found through the solid-state reaction between a single-crystalline Ge nanowire and Mn contact pads upon thermal annealing. The atomically clean interface between Mn(5)Ge(3) and Ge with a relatively small lattice mismatch of 10.6% indicates that Mn(5)Ge(3) is a high-quality ferromagnetic contact to Ge. Temperature-dependent I-V measurements on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire heterostructure reveal a Schottky barrier height of 0.25 eV for the Mn(5)Ge(3) contact to p-type Ge. The Ge nanowire field-effect transistors built on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) heterostructure exhibit a high-performance p-type behavior with a current on/off ratio close to 10(5), and a hole mobility of 150-200 cm(2)/(V s). Temperature-dependent resistance of a fully germanided Mn(5)Ge(3) nanowire shows a clear transition behavior near the Curie temperature of Mn(5)Ge(3) at about 300 K. Our findings of the high-quality room-temperature ferromagnetic Mn(5)Ge(3) contact represent a promising step toward electrical spin injection into Ge nanowires and thus the realization of high-efficiency spintronic devices for room-temperature applications.
为了探索通过热退火形成的锗纳米线异质结构中的自旋电子学应用，开发具有高居里温度的铁磁锗化物并利用 Ge 与形成的铁磁锗化物之间的高质量界面是至关重要的。在这项工作中，我们首次报道了 Mn(5)Ge(3)/Ge/Mn(5)Ge(3) 纳米线晶体管的形成和特性，其中通过单晶 Ge 纳米线与 Mn 接触垫之间的固态反应，在热退火后发现了室温铁磁锗化物。Mn(5)Ge(3)和 Ge 之间的原子级清洁界面具有相对较小的晶格失配 10.6%，表明 Mn(5)Ge(3)是高质量的铁磁 Ge 接触。对 Mn(5)Ge(3)/Ge/Mn(5)Ge(3) 纳米线异质结构的温度依赖性 I-V 测量表明，Mn(5)Ge(3)与 p 型 Ge 的肖特基势垒高度为 0.25 eV。基于 Mn(5)Ge(3)/Ge/Mn(5)Ge(3) 异质结构构建的 Ge 纳米线场效应晶体管表现出高性能的 p 型行为，电流开关比接近 10(5)，空穴迁移率为 150-200 cm(2)/(V s)。完全锗化的 Mn(5)Ge(3)纳米线的温度依赖性电阻在 Mn(5)Ge(3)的居里温度附近约 300 K 处表现出明显的转变行为。我们发现的高质量室温铁磁 Mn(5)Ge(3)接触代表了向 Ge 纳米线中电注入自旋的有希望的步骤，从而实现了用于室温应用的高效自旋电子器件。
