Fullerene-derivative-embedded nanogap field-effect-transistor and its nonvolatile memory application.

Adevice platformwith nanochannels, fabricated by either topdown or bottom-up nanofabrication technologies, has been attracting notable attention in various fields and applications. Asa representativecaseof suchnanochanneldeviceplatform,a nanogapembedded field-effect-transistor (FET) has shown a great potential as a fast and label-free detection tool for a specific target material by monitoring the changes in electrical characteristics such as the threshold voltageor conductivity. In a recent publication, for example, we reported that the nanogap-embedded FET can detect biomolecules in a very sensitive way by confining them within the nanogap and by monitoring the induced change in the effective dielectric constant of gate dielectrics, which is directly tied to the threshold voltage of the FET under study. Alternatively, a conductivity change that was induced upon bridging the gap with a conductive nanomedium was used as an unlabeled biosensor. In those devices, it is often difficult to confirm in a direct waywhether the nanogap or channel is really filledwith a target material due to its vulnerability under the common spectroscopicmethodsused for such study.That is, other than the indirect evidence providedby its ownelectrical signal, there is hardly any physical observation method that can give information on how far the fluids can infiltrate into the gap or channel. Given these facts, it would be beneficial to have molecules or nanostructures that are soluble and small enough to infiltrate nanometric gaps or channels and yet are robust and chemically stable enough tonot bedamagedduring electronmicroscopyor other spectroscopic techniques. It would be even better if electrical changes can be induced by filling the gap with those types of molecules or nanostructures. In that respect, fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is regarded as highly promising due to its high solubility,