Active modulation of ions and molecules via field-effect gating in nanofluidic channels is a crucial technology for various promising applications such as DNA sequencing, drug delivery, desalination, and energy conversion. Developing a rapid and facile fabrication method for ionic field-effect transistors (FET) over a large area may offer exciting opportunities for both fundamental research and innovative applications. Here, we report a rapid, cost-effective route for the fabrication of large-scale nanofluidic field-effect transistors using a simple, lithography-free two-step fabrication process that consists of sputtering and barrier-type anodization. A robust alumina gate dielectric layer, which is formed by anodizing sputtered aluminium, can be rapidly fabricated in the order of minutes. When anodizing aluminium, we employ a hemispherical counter electrode in order to give a uniform electric field that encompasses the whole sputtered aluminium layer which has high surface roughness. In consequence, a well-defined thin layer of alumina with perfect step coverage is formed on a highly rough aluminium surface. A gate-all-around nanofluidic FET with a leak-free gate dielectric exhibits outstanding gating performance despite a large channel size. The thin and robust anodized alumina gate dielectric plays a crucial role in achieving such excellent capacitive coupling. The combination of a gate-all-around structure with a leak-free gate dielectric over a large area could yield breakthroughs in areas ranging from biotechnology to energy and environmental applications.
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