Institute for Solid State Electronics, Vienna University of Technology, Vienna, Austria.
Nanotechnology. 2010 Oct 29;21(43):435704. doi: 10.1088/0957-4484/21/43/435704. Epub 2010 Sep 29.
Ge nanowires (NWs) about 2 µm long and 35 nm in diameter are grown heteroepitaxially on Si(111) substrates in a hot wall low-pressure chemical vapor deposition (LP-CVD) system using Au as a catalyst and GeH(4) as precursor. Individual NWs are contacted to Cu pads via e-beam lithography, thermal evaporation and lift-off techniques. Self-aligned and atomically sharp quasi-metallic copper-germanide source/drain contacts are achieved by a thermal activated phase formation process. The Cu(3)Ge segments emerge from the Cu contact pads through axial diffusion of Cu which was controlled in situ by SEM, thus the active channel length of the MOSFET is adjusted without any restrictions from a lithographic process. Finally the conductivity of the channel is enhanced by Ga(+) implantation leading to a high performance Ω-gated Ge-NW MOSFET with saturation currents of a few microamperes.
生长在 Si(111)衬底上的长约 2μm、直径 35nm 的锗纳米线（NWs）是在热壁低压化学气相沉积（LP-CVD）系统中使用 Au 作为催化剂和 GeH(4)作为前驱体异质外延生长的。通过电子束光刻、热蒸发和剥离技术，将单个 NW 与 Cu 衬垫连接。通过热激活相形成过程，实现了自对准和原子级锋利的准金属铜锗源/漏接触。Cu(3)Ge 段通过 Cu 的轴向扩散从 Cu 接触垫中出现，Cu 的扩散是通过 SEM 原位控制的，因此 MOSFET 的有效沟道长度可以在不受光刻工艺限制的情况下进行调整。最后，通过 Ga(+)注入提高了沟道的导电性，从而实现了高性能的 Ω 栅极锗 NW MOSFET，饱和电流达到几微安。
