Electrochemical nanofabrication of electronics, an example of making nonvolatile memory device

Speaker:

Di Wei Research Scientist, Nokia

In this work we describe a simple electrochemical process to fabricate an air stable nonvolatile memory device based on polyaniline (PANI) and gold (Au) nanoparticles in one step. PANI and Au particle composite material was synthesized by cyclic voltammetry on a modified ITO (MITO) glass in the room-temperature ionic liquid (IL), 1-ethyl-3-methyl-imidazolium tosylate [EMIM][Tos] containing 1 M trifluoroacetic acid. The Au particles were synthesized during electropolymerization of aniline and distributed in the PANI matrix. It is the first time to report the electrochemical synthesis of such material in IL. This material can be used directly as air stable nonvolatile memory device. Both bistability (switching) and Negative Differential Resistance (NDR) were observed in this single layer device as Fig.1 shows. It demonstrates that the memory effect originates only from the PANI:Au composite and the device made with just PANI without any Au nanoparticles (MITO/PANI/Al) shows no electronic switching. The PANI:Au composite film can be deposited directly on the MITO glass by electrochemical methods and this simplifies fabrication of the memory device significantly. The impedance states are nonvolatile in nature and can be read and switched several times with minimal degradation in air. For example, the composite PANI:Au material was kept in air for 7 weeks and the NDR characteristic was still repeatable. That makes it possible to use these composite materials in printable electronics.