Fullerene Nanostructure-Coated Channels Activated by Electron Beam Lithography for Resistance Switching

Abstract

Fullerenes, which are spherical molecules composed entirely of carbon, have attractive homogeneous shapes at subnanometer sizes and inherent physical and chemical properties that make them promising for use in nanoelectronics. In addition, fullerenes can be chemically functionalized with substitutional elements, which have been incorporated into devices to substantially improve their transport properties. The chemically functionalized fullerenes are known as fullerene derivatives. Using the chemically functionalized fullerene pyrrolidine tris-acid (CPTA), we developed a new device fabrication scheme for a fullerene resistance-switching element generated by the polymerization and depolymerization of C 60 polymer strings. To take advantage of the CPTA property, whereby it forms strong interactions with the surface of a substrate by strengthening the chemical bonds, a uniform thin CPTA film was spin-coated, and conductive fullerene polymerization was subsequently stimulated by a designed scan with an electron beam lithography (EBL) preset. The polymerized channel showed negative differential resistance in its current−voltage characteristics and performed twostate resistance switching, indicating that the polymerization and depolymerization of the C 60 polymer strings were alternatively controlled according to the external voltage input. EBL fabrication with solution-based nanomaterial coating has the potential of a bottom-up scheme for nanoelectronics, allowing for the design of intrinsic material properties.

Electromechanical Switching of a C60 Chain in a Nanogap

“…This NDR is a turn-off point from a high current in a low-resistance state (LRS) to a low current in a highresistance state (HRS). 21,30,32,38 Under a current, channel heating can remove the chemical functional additive of −COOH from the CPTAs and change it to free C 60 s as the chemical substitute element from the C 60 surface removed at 200−300 °C. For PCBM, its chemical substituent element can be removed at 340 °C to return to the original C 60 s. 39 After the removal of the functional additive, the C 60 position could be rearranged under a high electric field between the narrow nanogap and allow a denser packing of C 60 s to increase the current.…”

“…However, as STM is an observation tool for nanoscale objects, a basic phenomenon should be represented as a solid-state device for its verification. Therefore, we equipped fixed electrodes with source and drain electrodes for C 60 devices. ,− …”

“…Thus, we developed thin-film devices using CPTA. 32 The design of the electron irradiation area allows the fabrication of conductive channels for arbitrary device shapes and fabrication of a narrow and short channel, which is important for a high-performance NDR switch. Nanogap fabrication could realize a single or small number of fullerene channels for the observation of the electrical behavior of individual fullerenes.…”

“…Functionalized fullerenes dissolved in the solution have an advantage in the film-coating process. Thus, we developed thin-film devices using CPTA . The design of the electron irradiation area allows the fabrication of conductive channels for arbitrary device shapes and fabrication of a narrow and short channel, which is important for a high-performance NDR switch.…”

Dependence of Charge Transfer on the Adsorption Site at Metal–Molecule Interfaces: Implications for Single-Molecule Electronic Devices

“…The primary effect of charge transfer is alteration of the energy-level alignment at the interface by the surface dipole. − Consequently, the electronic properties of the metal–molecule interface are modulated compared with the properties of the isolated state of the components. At the single-molecule level, where much effort has been devoted to the fundamental and applied development, − ,, these interfacial effects become prominent to deteriorate the desired property or to induce novel functionality. The latter consequence is attractive especially in the development of single-molecule electronic devices for molecular electronics.…”