Short-channel nanowire transistor using a nanoporous crystal semiconductor 12CaO·7Al2O3

12CaO·7Al2O3 (C12A7) is an electrical insulator with a band gap ∼7.5 eV. Contrary to conventional ultra-large gap oxides, electrical conductivity of C12A7 is controllable over a very wide range of 10−10 to 103 S cm−1 by electron doping to a unique conduction band arising from 3-dimensionally connected sub-nanometer-sized cages constituting the crystal structure. This feature provides opportunities to develop a new electronic device. In this study, we fabricated side-gated transistors using C12A7:e− nanowire (NW) channels. The carrier concentration in the as-doped NW channel (Ne > 1020 cm−3) was too high to operate transistors, and therefore Ne was reduced by low-temperature oxidation and controlled to be ∼1014 cm−3. Current modulation by gate voltage sweep was clearly observed in semiconducting C12A7:e− NW channels at room temperature. Moreover, by reducing the channel length from ∼2 μm to ∼100 nm, the magnitude of the current modulation was drastically increased and the on–off current ratio larger than 102 was obtained.