Non-volatile memory devices with redox-active diruthenium molecular compound

Reduction-oxidation (redox) active molecules hold potential for memory devices due to their many unique properties. We report the use of a novel diruthenium-based redox molecule incorporated into a non-volatile Flash-based memory device architecture. The memory capacitor device structure consists of a Pd/Al2O3/molecule/SiO2/Si structure. The bulky ruthenium redox molecule is attached to the surface by using a 'click' reaction and the monolayer structure is characterized by x-ray photoelectron spectroscopy to verify the Ru attachment and molecular density. The 'click' reaction is particularly advantageous for memory applications because of (1) ease of chemical design and synthesis, and (2) provides an additional spatial barrier between the oxide/silicon to the diruthenium molecule. Ultraviolet photoelectron spectroscopy data identified the energy of the electronic levels of the surface before and after surface modification. The molecular memory devices display an unsaturated charge storage window attributed to the intrinsic properties of the redox-active molecule. Our findings demonstrate the strengths and challenges with integrating molecular layers within solid-state devices, which will influence the future design of molecular memory devices.

Solid and liquid spectroscopic analysis (SALSA)--a soft x-ray spectroscopy endstation with a novel flow-through liquid cell

We present a novel synchrotron endstation with a flow-through liquid cell designed to study the electronic structure of liquids using soft x-ray spectroscopies. In this cell, the liquid under study is separated from the vacuum by a thin window membrane, such that the sample liquid can be investigated at ambient pressure. The temperature of the probing volume can be varied in a broad range and with a fast temperature response. The optimized design of the cell significantly reduces the amount of required sample liquid and allows the use of different window membrane types necessary to cover a broad energy range. The liquid cell is integrated into the solid and liquid spectroscopic analysis (SALSA) endstation that includes a high-resolution, high-transmission x-ray spectrometer and a state-of-the-art electron analyzer. The modular design of SALSA also allows the measurement of solid-state samples. The capabilities of the liquid cell and the x-ray spectrometer are demonstrated using a resonant inelastic x-ray scattering map of a 25 wt % NaOD solution.