A research group at the International Center for Materials Nanoarchitectonics (MANA) have developed thin-film capacitors using a new high-permittivity (high-k) dielectric sheet with molecular-level thickness (~1 nm). The researchers were led by MANA scientist Dr. Minoru Osada and principal investigator Dr. Takayoshi Sasaki at the National Institute for Material Science (NIMS) in Japan.
The technology is expected to revolutionize next-generation electronics. According to the International Technology Roadmap for Semiconductors (ITRS), good insulating, high-k nanofilms are expected to be key to future applications. The new research demonstrates simultaneous improvements in a number of material properties, including relative permittivity, lower loss and leakage current. The solution-based room-temperature process using oxide nanosheets as building blocks opens multiple possibilities for the development of high-k dielectrics in capacitor technology, gate insulators in organic field effect transistors, energy-storage devices, and also future flexible electronics.
MANA researchers created thin films based on titanium-niobate nanosheets (TiNbO5, Ti2NbO7, Ti5NbO14) as building blocks. The research group delaminated layered oxides and stacked sheets on an atomically flat SrRuO3 substrate, creating films between 5 and 15 nm thick. The thin-film capacitors developed by this method have excellent dielectric characteristics, achieving the world’s highest performance permittivity (160 ~ 300) with a film thickness of 5 ~ 15 nm.
The researchers relate the dielectric performance of the nanofilms to the structural features. In these nanosheets, the octahedral distortion inherent to site engineering by Nb doping results in a giant molecular polarizability. New cooperative functions that originate from the mutual interactions between nanoscale structural units comprise the focus of nanoarchitectonics, the discipline at the center of MANA research.
The International Center for Materials Nanoarchitectonics (MANA) is one of the five research centers selected as part of the World Premier International (WPI) Research Center Initiative, which was launched by Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT) in 2007. A sixth research center was added in Kyushu University in 2010.