Non-volatile Memory Using Embedded Gold Nanoparticles in Polymer Dielectric PDF Download

Author: Poh Choon Ooi
Publisher:
ISBN:
Category : Ferroelectric storage cells
Languages : en
Pages : 240

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Book Description
Many recent studies have been conducted on optically transparent and mechanically flexible polymer memory devices due to its additional benefits in comparison to conventional electronic devices for various applications, such as vision-free products, see-through electronic devices; head-up displays, and produces a class of system-on-glass for use in see through and flexible electronic devices. There are numerous studies on transparent and flexible non-volatile memory (NVM) based on organic thin film transistor (OTFT) using different charge trap mediums. Although some promising results have been achieved in OTFT study, however, the fabrication process is complicated with many stacking layers to achieve the bistable memory effect with three-terminal contacts to operate the transistors. Therefore, for simplicity and ease in fabrication while achieving the bistable memory effect, the transparent and flexible organic bistable device (OBD) has been designed as metal-insulator-semiconductor (MIS) structure with two-terminal contacts to operate the device and using metal nanoparticles as charge trap medium has been of interest lately. The advantages of metallic nanoparticles storage layers stem from the large work functions difference with Si substrate, which ensures deep potential wells that enhance carrier confinement; hence avoiding retention loss. In addition, noble metals such as gold do not oxidize and do not react with the surrounding dielectric layers. Hence, a simple fabrication route using a simple solution process to construct a large area, optically transparent and flexible memory based on MIS structure with embedded AuNPs is proposed in this study. The preliminary study has begun with the fabrication of opaque and rigid MIS memory devices using p-type Si substrate. The organic-inorganic (hybrid) dielectric polymethylsilsesquioxane (PMSSQ) embedded with gold nanoparticles (AuNPs) are used as the insulator layer and charge storage medium in the MIS structure. The use of polymer materials as insulator layer is driven by the possibility of enabling new applications in flexible and transparent electronic devices. Polymer materials offer an alternative fabrication process for the large area electronics, because it provides simpler process, lower cost, and higher throughput, compared with the vacuumdeposition- based process. In this preliminary study, spin-coating method is used to deposit the PMSSQ and AuNPs in polymer host. Subsequently, the electrical characterization has been performed on a MIS NVM device to understand the transport mechanisms through thin insulator and proposed. Although some promising memory characteristics have been obtained from preliminary study; however, spin-coating deposition of AuNPs in the polymer host results in high percentage of non-operational non-volatile memory devices due to the non-uniformly distributed AuNPs attributed to the centrifugal force during spin-coating. Therefore, a novel hydrothermally grown AuNPs directly on the Si substrate has been proposed to improve the distribution of AuNPs. Then, the research proceeds to realize transparent and flexible NVM devices using a simple solution process. Here, the MIS stacking structure is constructed on the flexible indium-tin-oxide (ITO) coated polyethylene terephthalate (PET) as a bottom transparent and conducting electrode, and the replacement of p-Si substrate with pentacene as an active layer. However, they also suffer non-uniformity in AuNPs due to spin-coating of PMSSQ. Lastly in an attempt to achieve non-volatile memory devices based on simple metal-insulatormetal (MIM) structure, AuNPs embedded in parylene-C with two sandwiching metals were realized. Electrical characterization has been performed on these MIM devices to examine and propose the charge transport mechanisms. As a result, it has better yield of operational nonvolatile memory devices because the vapor deposition of parylene does not disturbed the AuNPs. Further the parylene deposition does not introduce thermal stress on the flexible ITO coated PET substrate.