Institute for Solid State Electronics, Vienna University of Technology, Vienna, Austria.
Nano Lett. 2011 Aug 10;11(8):3108-12. doi: 10.1021/nl201105k. Epub 2011 Jul 11.
In this Letter we report the atypical self-activation of gallium (Ga) implanted by focused ion beam (FIB) into germanium nanowires (Ge-NWs). By FIB implantation of 30 keV Ga(+) ions at room temperature, the Ge-NW conductivity increases up to 3 orders of magnitude with increasing ion fluence. Cu(3)Ge heterostructures were formed by diffusion to ensure well-defined contacts to the NW and enable two point I/V measurements. Additional four point measurements prove that the conductivity enhancement emerges from the modification of the wires themselves and not from contact property modifications. The Ga distribution in the implanted Ge-NWs was measured using atom probe tomography. For high ion fluences, and beginning amorphization of the NWs, the conductivity decreases exponentially. Temperature dependent conductivity measurements show strong evidence for an in situ doping of the Ge-NWs without any further annealing. Finally the feasibility of improving the device performance of top-gated Ge-NW MOSFETs by FIB implantation was shown.
在这封信件中，我们报告了聚焦离子束（FIB）注入锗纳米线（Ge-NWs）中的镓（Ga）的非典型自激活。通过在室温下用 30keV Ga(+)离子进行 FIB 注入，随着离子注入剂量的增加，Ge-NW 的电导率增加了 3 个数量级。通过扩散形成 Cu(3)Ge 异质结构，以确保与 NW 之间有良好定义的接触，并实现两点 I/V 测量。附加的四点测量证明，电导率的增强源于线本身的改性，而不是接触性质的改性。使用原子探针层析成像测量了注入 Ge-NWs 中的 Ga 分布。对于高离子注入剂量和 NW 开始非晶化的情况，电导率呈指数下降。温度相关的电导率测量为原位掺杂 Ge-NWs 提供了有力证据，而无需进一步退火。最后，通过 FIB 注入提高顶部栅 Ge-NW MOSFET 器件性能的可行性得到了证明。
