Single-Electron Charging Effects in Hybrid Organic/Inorganic Nanomembrane-Based Junctions
R. F. Oliveira, L. Merces, F. Marques, E. Teixeira-Neto, D. H. S. de Camargo and C. C. B. Bufon*
One of the main questions of modern science and technology is how to explore the properties of the matter down to the quantum limits. Regarding the electronic properties, one possibility lies in the controlled transfer of individual electrons in a piece of matter (viz. nanostructure) or nanoscale device. In so-called single-electron devices (SEDs), electrons are transferred one-by-one to the particular region of the device by tunneling, due to the discreteness of such transport characteristics. SEDs are commonly engineered by combining two tunnel junctions connected in series, having a conductive nanostructure (called island) in between. In this work, we demonstrated a novel SED architecture based on rolled-up nanomembranes (rNMs), semiconducting molecular layers (SMLs) and the controlled, in situ migration of metal particles induced by electric field. The rNMs are used to establish a soft connection with SMLs by connecting them from the top in a two-electrode diode configuration. Here, we employed as SMLs, physisorbed 5 nm-thick copper (II) phthalocyanine molecules – an air-stable, organic semiconductor widely used in several electronics applications. Because of the ultrathin nature of the junction, electric fields of 1−4 MV/cm are easily reached. Thus, metal nanoparticles from the contacts are detached by the action of the electric field and get trapped into the SME matrix. As a result, single-electron charging effects namely Coulomb blockade and Coulomb staircase are observed at low temperatures (10 K). This process can be considered a viable approach to create novel and complex SEDs, for example, by using different SMLs. From another perspective, the reported in situ, field-induced electrode diffusion in such nanoscale junctions deserves attention as the features of the hybrid device can occasionally mask the electrical signatures from other phenomena, such as molecule-dependent responses.
This work was featured on the front cover of The Journal of Physical Chemistry C (JPCC), volume 122, issue 23, June 2018. The authors acknowledge FAPESP (2014/25979-2), CAPES, SisNANO and CNPq. For more information, visit: https://pubs.acs.org/toc/jpccck/122/23.