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In this paper, organic thin films of a nonlinear optical (NLO) material ((E)-1-ferrocenyl-2-(l-methyl-4-pyridiniumyl) ethylene iodide) were prepared by a vacuum deposition method. The typical I–V curve of the film exhibits a favorable room-temperature bistability. Further recording experiments have been performed with a scanning tunneling microscope, which confirmed that the thin film of the donor–π–acceptor NLO material could certainly be applied for nanoscale data storage. The average size of the recorded marks is about 1.5 nm. Mechanism analyses suggest that the formation of the recording dots is due to the local change of electrical property of the thin film, and the intermolecular charge transfer induced by an electric field is proposed as the reason for the change. [ABSTRACT FROM AUTHOR]

The authors found CuOx thin film with gradual oxygen concentration (GOC) distribution enhances resistive switching characteristics for nonvolatile memory applications. By using Al/GOC CuOx/Cu structure, not only no forming is needed but also the endurance of switching is greatly enhanced. The device with GOC CuOx demonstrates resistance on/off ratio of greater than 100 and endurance of more than 12 000 cycles. The “forming-free” characteristics appear related to thinner CuO and the endurance enhancement appears related to gradual gradient of oxygen vacancies in CuOx. Thus, the thickness of CuO and distribution of oxygen (as well as vacancies) play important roles for performance improvement. [ABSTRACT FROM AUTHOR]

Nanometer-scale recording on an organic-complex thin film with a scanning tunneling microscope (STM) under ambient conditions is demonstrated. The recording marks are made by applying external voltage pulses between the tip and the highly ordered pyrolytic graphite substrate. A 30×30 nm2 STM image with recorded marks is given. The average recorded mark is 1.3 nm in diameter, which corresponds to a data storage density of about 1013 bits/cm2. The current–voltage characteristics measured by the STM show an insulator behavior for the unrecorded regions, and a conductor behavior for the recorded regions, which indicates that the data are recorded by local change of the electrical property of the films. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present a direct observation of a structural transition at molecular scale in an organic p-nitrobenzonitrile (PNBN) thin film using scanning tunneling microscopy (STM). STM images clearly show an ordered molecular structure of unrecorded regions in the films, while the PNBN molecular arrangements are disordered in the recorded regions. The current-voltage (I-V) measurements from the STM demonstrate a great increase of the conductance transition in the recorded regions after the voltage pulses. Those results suggest that the recording mechanism may be due to a crystalline structural transition, which is consistent with our previously proposed mechanism in another organic system for ultrahigh density data storage. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A thin film of 1,1-dicyano-2,2-(4-dimethylaminophenyl) ethylene (DDME) has been grown by a modified vacuum deposition. The films were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning tunneling microscopy (STM). Highly ordered parallel molecular stacks were repeatedly observed with STM under ambient conditions. The dc current-voltage (I-V) characteristics of device Au/DDME/Au were measured, and the film was found to possess good electrical bistability and electrochromic properties. Nanometer-scale recording was realized on the film by applying pulse voltage between the STM tip and substrate. The possible switching mechanism is discussed. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]