TY - JOUR
T1 - Electrical Conduction of Superatom Thin Films Composed of Group-V-Metal-Encapsulating Silicon-Cage Nanoclusters
AU - Yokoyama, Takaho
AU - Chiba, Tatsuya
AU - Hirata, Naoyuki
AU - Shibuta, Masahiro
AU - Nakajima, Atsushi
N1 - Funding Information:
We are grateful to Dr. Hironori Tsunoyama for valuable discussion and to Prof. H. Yamamoto (Institute for molecular science) for fruitful discussion on electrical conduction mechanism, to Ms. K. Tanaka (Center Service Facilities for Science and Technology Research, Keio University) for SEM measurements. This work is partly supported by JSPS KAKENHI of Grants-in-Aid for Scientific Research (A) Grant Numbers 15H02002 and 19H00890, of Challenging Research (Pioneering) Grant Number 17H06226 and of Research Fellowships for Young Scientists Grant Number 19J22141.
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/8/26
Y1 - 2021/8/26
N2 - Nanocluster assembled films have attracted great interest for designing nanostructured materials with unique electromagnetic properties through a bottom-up approach. Superatoms of group-5 metals (MV = V, Nb, and Ta) encapsulating silicon (Si) cage nanoclusters (MV@Si16), which are synthesized by high-power impulse magnetron sputtering technique, can be efficiently generated to form assembled films. Temperature-dependent current-voltage (I-V) characteristics of the MV@Si16 assembled films revealed that the electrical conduction mechanism is not band transport but hopping transport with Efros-Shklovskii variable range hopping for all central MV atoms. The results show that electrons involved in conduction are strongly correlated to localized electronic states; this correlation arises because of not only the geometrical disordering in noncrystalline assembled films but also the electronic nature of a superatomic 1H orbital with multiple nodes. The localization length depends on the specific MV and is several times the radius of MV@Si16 (0.45 nm); it is the largest for Ta (2.2 nm) and the smallest for Nb (0.8 nm), revealing a periodicity of superatoms.
AB - Nanocluster assembled films have attracted great interest for designing nanostructured materials with unique electromagnetic properties through a bottom-up approach. Superatoms of group-5 metals (MV = V, Nb, and Ta) encapsulating silicon (Si) cage nanoclusters (MV@Si16), which are synthesized by high-power impulse magnetron sputtering technique, can be efficiently generated to form assembled films. Temperature-dependent current-voltage (I-V) characteristics of the MV@Si16 assembled films revealed that the electrical conduction mechanism is not band transport but hopping transport with Efros-Shklovskii variable range hopping for all central MV atoms. The results show that electrons involved in conduction are strongly correlated to localized electronic states; this correlation arises because of not only the geometrical disordering in noncrystalline assembled films but also the electronic nature of a superatomic 1H orbital with multiple nodes. The localization length depends on the specific MV and is several times the radius of MV@Si16 (0.45 nm); it is the largest for Ta (2.2 nm) and the smallest for Nb (0.8 nm), revealing a periodicity of superatoms.
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U2 - 10.1021/acs.jpcc.1c03591
DO - 10.1021/acs.jpcc.1c03591
M3 - Article
AN - SCOPUS:85114117800
SN - 1932-7447
VL - 125
SP - 18420
EP - 18428
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 33
ER -