Floating nanodot gate memory fabrication with biomineralized nanodot as charge storage node

Abstract

We have demonstrated floating nanodot gate memory (FNGM) fabrication by utilizing uniform biomineralized cobalt oxide (Co3O4) nanodots (Co-BNDs) which are biochemically synthesized in the vacant cavity of supramolecular protein, ferritin. High-density Co-BND array (>6.5×1011cm−2) formed on Si substrate with 3-nm-thick tunnel SiO2 is embedded in metal-oxide-semiconductor (MOS) stacked structure and used as the floating gate of FNGM. Fabricated Co-BND MOS capacitors and metal-oxide-semiconductor field effect transistors show the hysteresis loop due to the electron and hole confinement in the embedded Co-BND. Fabricated MOS memories show wide memory window size of 3–4V under 10V operation, good charge retention characteristics until 104s after charge programming, and stress endurance until 105 write/erase operation. Observed charge injection thresholds suggest that charge injection through the direct tunneling from Si to the energy levels in the conduction and valence bands of Co3O4 and long charge retention characteristics implies prompt charge confinement to the deeper energy level of metal Co which is formed during the annealing in the device processing.

Characterisation of a carbon nanotube random network conjugated by semiconductor nanoparticles with defined nanometre-scaled gaps

“…The fluctuation may reflect the electron trapping by, or electron emitting from the NPs that surround the CNTs. The hysteresis may reflect formation of conductive paths as a result of Co oxide reduction within NPs [10].…”

“…Synthesis of Co oxide NPs within NHBP-LiDps proteins: Co oxide NPs were synthesised within the NHBP-LiDps proteins because electronic memory functions were observed in the previous reports [8][9][10]. The NHBP-LiDps protein (0.1 mg/ml) was dissolved in 100 mM HEPES-NaOH (pH 8.2) buffer and incubated in the presence of 0.5 mM (NH 4 ) 2 Co(SO 4 ) 2 and 1 mM H 2 O 2 at 50 8C for 15 min.…”

“…Various metal-or semiconductor-materials can be synthesised inside the cavity to form NPs. The NPs synthesised inside proteins can function as charge storage nodes [8][9][10]. The LiDps proteins with NP cores adhere to the surface of CNTs.…”

Nanoscale device architectures derived from biological assemblies: The case of tobacco mosaic virus and (apo)ferritin

“…37) After the protein was removed by UV=ozone treatment, the NPs were buried in a 17 nm control layer of silicon oxide. [159][160][161][162][163] The Co 3 O 4 NP MOSFET required annealing in forming gas after electrode deposition [ Fig. 8(a)].…”

Characterization of floating-gate memory device with thiolate-protected gold and gold-palladium nanoclusters

“…Note that it is crucial to measure the reference curve for each device for evaluating the C-V curves, because the structural variation between devices causes shifts of reference curves for values around 0.1 V. The hysteresis behavior indicates that both holes and electrons are injected into the nanoclusters from the Au electrode; holes are injected with a positive gate bias, while electrons are injected with a negative gate bias. The flatband voltage shift, corresponding to gate-voltage at a half of maximum capacitance (C max ), 28,[44][45][46] was evaluated instead of that defined as gate-voltage at the maximum in G (conductance)-V curve, because the former matches by 0.1 V with the latter; the latter has been frequently used for estimating flat-band voltage. We have found that the flatband voltage is independent of the sweep rate and frequency (Figs.…”