Floating gate metal-oxide-semiconductor capacitor employing array of high-density nanodots produced by protein supramolecule

An array of high-density 1.8 x 10(12) cm(-2) floating nanodots was embedded within a metal-oxide-semi conductor (MOS) capacitor using a cage-shaped protein supramolecule, Listeria ferritin (Lis-fer). A monolayer of Lis-fer with a 4.5 nm ferrihydrite core was adsorbed on a 3 nm tunneling SiO2 layer on a p-Si substrate by 3-aminopropyl-triethoxysilane (APTES) surface modification. The outer protein was selectively removed and the obtained cores were covered with a 20-nm-thick control SiO2 layer and an aluminum electrode. The MOS capacitor was annealed in reducing gas (H-2 : N-2 = 10 : 90%), and the embedded cores were reduced to conductive nanodots. The capacitance-voltage characteristics of the MOS capacitor measured at I MHz by applying a DC bias voltage from -5 to +5 V showed a clear hysteresis. This result indicates that the array of nanodots produced and positioned by Lis-fer has the ability for electron confinement.