Silver Nanofilament Formation Dynamics in a Polymer‐Ionic Liquid Thin Film by Direct Write
Year: 2019
Type: article
Abstract: Silver nanofilament formation dynamics are reported for an ionic liquid (IL)‐filled solid polymer electrolyte prepared by a direct‐write process using a conductive atomic force microscope (C‐AFM). Filaments are electrochemically formed at hundreds of xy locations on a ≈40 nm thick polymer electrolyte, polyethylene glycol diacrylate (PEGDA)/[BMIM]PF6. Although the formation time generally decreases with increasing bias from 0.7 to 3.0 V, an unexpected non‐monotonic maximum is observed ≈2.0 V. At voltages approaching this region of inverted kinetics, IL electric double layers (EDLs) become detectable; thus, the increased nanofilament formation time can be attributed to electric field screening, which hinders silver electromigration and deposition. Scanning electron microscopy confirms that nanofilaments formed in this inverted region have significantly more lateral and diffuse features. Time‐dependent formation currents reveal two types of nanofilament growth dynamics: abrupt, where the resistance decreases sharply over as little as a few ms, and gradual where it decreases more slowly over hundreds of ms. Whether the resistance change is abrupt or gradual depends on the extent to which the EDL screens the electric field. Tuning the formation time and growth dynamics using an IL opens the range of accessible resistance states, which is useful for neuromorphic applications.
Source: Advanced Functional Materials
Institutions: University of Pittsburgh, University of Notre Dame
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Awards: G4979838128, IN THIS PROPOSAL THE FUNDAMENTAL QUANTUM AND PHOTONIC INTERACTIONS OF BIMETALLIC ATOMIC-SCALE JUNCTIONS (ASJS) WILL BE EXPLORED WITH THREE MAJOR SPACE TECHNOLOGY-RELATED APPLICATIONS IN FOCUS: 1)CHEMICAL SENSING 2)SMART/METAMATERIALS AND 3)MEMRISTORBASED COMPUTING. AN ASJ IS A TYPE OF QUANTUM-POINT CONTACT CREATED BY ELECTROCHEMICALLY DEPOSITING SILVER BETWEEN TWO NANOSCALE ELECTRODES. THIS CONNECTION CAN BE FORMED AND DESTROYED BY APPLYING THE APPROPRIATE VOLTAGE POTENTIAL ACROSS THE ELECTRODES AND THUS CONTROLLED TO THE POINT WHERE THE JUNCTION NARROWS TO THE WIDTH OF A SINGLE ATOM. AT THIS POINT THE JUNCTION CAN EXHIBIT A PHENOMENON KNOWN AS QUANTIZED CONDUCTANCE. IN THIS REGION THE JUNCTION IS ESPECIALLY SENSITIVE TO DISTURBANCES IN THE SURROUNDING ENVIRONMENT. PREVIOUS RESEARCH HAS DEMONSTRATED THE POTENTIAL OF A SINGLE ASJ IN SENSING CHEMICALS BOUND TO THE JUNCTION AT THIS NARROWEST SECTION; THIS PROPOSAL WILL EXTEND ON THAT WORK BY EXAMINING PARALLEL AND SERIAL ARRAYS OF ASJS FOR CHEMICAL SENSING AND MEMRISTIVE COMPUTING AS WELL AS THE INTERACTION OF THE JUNCTIONS IN 3-DIMENSIONAL CONFIGURATIONS WITH LIGHT FOR METAMATERIALS. THE OBJECTIVES OF THIS PROJECT ARE TO ESTABLISH CONTROL OVER JUNCTION GROWTH IN MASSIVELY PARALLEL ARRAYS BOTH THROUGH DIRECT ELECTRICAL CONTACT AND WITH PHOTO-INDUCED CHARGING THEN UTILIZE THIS CONTROL TO EXAMINE THE POTENTIAL APPLICATION OF THESE JUNCTIONS IN THE AREAS DESCRIBED ABOVE. JUNCTIONS WILL BE CREATED USING ELECTROCHEMICAL DEPOSITION BETWEEN CONDUCTIVE ELECTRODES WHICH MAY BE LITHOGRAPHICALLY-DEFINED MACROSCALE ELECTRODES ON A WAFER A CONDUCTIVE AFM TIP OR NANOPARTICLES STIMULATED WITH FOCUSED LASERS. ACHIEVING THESE OBJECTIVES WOULD BE HIGHLY SIGNIFICANT TO BOTH NASA AND THE COMMUNITY AT LARGE. DUE TO THE JUNCTIONS SMALL SPACE AND WEIGHT A MASSIVELY PARALLEL ARRAY OF JUNCTIONS WOULD NOT TAKE UP MORE THAN A FEW SQUARE MILLIMETERS OF AREA ON A SILICON WAFER YET COULD PERFORM A WIDE ARRAY OF FUNCTIONS; THUS THEY ARE IDEALLY SUITED TO THE TIGHT WEIGHT AND SIZE REQUIREMENTS OF TERRESTRIALLYLAUNCHED SPACE MISSIONS. THE APPLICATIONS OF ASJS IN CHEMICAL SENSING AND MEMRISTOR-BASED NEURAL NETWORK APPLICATIONS COULD ALLOW FOR NEW EXPERIMENTS AND DATA ANALYSIS NOT POSSIBLE WITH EXISTING TECHNOLOGY. IN ADDITION THE FUNDAMENTAL INSIGHTS INTO QUANTUM AND PHOTONIC PHENOMENA GAINED BY DEVICES THAT OPERATE AT ROOM-TEMPERATURE AND UNDER SIMPLE CONDITIONS WOULD ALSO GREATLY BENEFIT THE SCIENTIFIC COMMUNITY AND SCIENCE EDUCATION.
OpenAlex ID: W2991305078