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Posted: August 30, 2010
Development of world's highest performance thin-film condenser
(Nanowerk News) A research group headed by MANA Scientist Dr. Minoru Osada and Principal Investigator Dr. Takayoshi Sasaki of the International Center for Materials Nanoarchitectonics (MANA) at the National Institute for Materials Science (NIMS) discovered a new high-k dielectric nanosheet with a molecular level thickness (∼1.5 nm), and successfully developed the world's highest performance thin-film condenser by a solution-based bottom-up nanotechnology
Condensers based on dielectric thin films are a key component of electronic devices, where they perform essential functions such as storing electrical charge, and blocking direct current while allowing alternating currents to propagate. Because condensers are the largest components in our electronic equipments such as cell phones, personal computers, etc., extensive efforts are directed at the developments of high performance condensers with smaller size and higher capacitance.
Central to these researches is the design and integration of ultrathin high-k dielectrics such as perovskite-structure BaTiO3 and (Ba1-xSrx)TiO3, which should provide more capacitance per unit area of device. However, current perovskite thin films yield reduced dielectric constants that are one order of magnitudesmaller than bulk values. This so-called size effect is a long-standing conundrum in perovskite dielectrics, which limits further miniaturization and enhanced capacitance in condensers devices.
This research group conducted a search for new high-k nanodielectrics, and discovered a moleculary thin high-k nanosheet (perovsikte nanosheet) that afford robust high-k properties even at several nanometer thicknesses, allowing high capacitances. By solution-based bottom-up approach using perovskite nanosheets, the group successfully fabricated thin-film condensers directly on SrRuO3 or Pt substrates with a clean interface. These devices exhibited a high capacitance density (with dielectric constant of 210 - 240), the largest value seen so far in current perovskite films with the thickness down to 10 nm. This result enables further miniaturization and enhanced capacitance in thin film condensers, and opens a new route to the development of high performance condenser devices desirable for future electronic equipments.
This research was carried out as part of the research project "Development of Nanomaterials/Manufacturing Processes for Next-generation Electronics Using Inorganic Nanosheets" (Project Leader: Takayoshi Sasaki) in the "Establishment of Innovative Manufacturing Technology Based on Nanotechnology" Research Area ofthe Core Research of Evolutional Science & Technology (CREST) Program of the Japan Science and Technology Agency (JST). This result was published in the online edition of ACS Nano on August 24.