Micro and Nanosystems, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Nat Nanotechnol. 2010 Aug;5(8):589-92. doi: 10.1038/nnano.2010.129. Epub 2010 Jul 4.
Single-walled carbon nanotubes offer high sensitivity and very low power consumption when used as field-effect transistors in nanosensors. Suspending nanotubes between pairs of contacts, rather than attaching them to a surface, has many advantages in chemical, optical or displacement sensing applications, as well as for resonant electromechanical systems. Suspended nanotubes can be integrated into devices after nanotube growth, but contamination caused by the accompanying additional process steps can change device properties. Ultraclean suspended nanotubes can also be grown between existing device contacts, but high growth temperatures limit the choice of metals that can be used as contacts. Moreover, when operated in ambient conditions, devices fabricated by either the post- or pre-growth approach typically exhibit gate hysteresis, which makes device behaviour less reproducible. Here, we report the operation of nanotube transistors in a humid atmosphere without hysteresis. Suspended, individual and ultraclean nanotubes are grown directly between unmetallized device contacts, onto which palladium is then evaporated through self-aligned on-chip shadow masks. This yields pairs of needle-shaped source/drain contacts that have been theoretically shown to allow high nanotube-gate coupling and low gate voltages. This process paves the way for creating ultrasensitive nanosensors based on pristine suspended nanotubes.
单壁碳纳米管作为纳米传感器中的场效应晶体管，具有灵敏度高和功耗极低的优点。在化学、光学或位移传感应用以及谐振机电系统中，将纳米管悬浮在两个触点之间，而不是将其附着在表面上，具有许多优势。悬浮纳米管可以在纳米管生长后集成到器件中，但是伴随的额外工艺步骤引起的污染可能会改变器件性能。超洁净悬浮纳米管也可以在现有器件触点之间生长，但是高温生长限制了可以用作触点的金属的选择。此外，当在环境条件下操作时，通过后生长或预生长方法制造的器件通常表现出栅极滞后，这使得器件行为的再现性降低。在这里，我们报告了在没有滞后的情况下在潮湿气氛中操作的纳米管晶体管。悬浮的、单个的和超洁净的纳米管直接在未金属化的器件触点之间生长，然后通过自对准的芯片上掩模将钯蒸发到其上。这产生了一对针状源/漏极接触，理论上表明它们允许高的纳米管-栅极耦合和低的栅极电压。该工艺为基于原始悬浮纳米管的超高灵敏纳米传感器的创建铺平了道路。
