The single event effect in ferroelectric-gate field-effect transistor (FeFET) under heavy ion irradiation is investigated in this paper. The simulation results show that the transient responses are much lower in a FeFET than in a conventional metal-oxide-semiconductor field-effect transistor (MOSFET) when the ion strikes the channel. The main reason is that the polarization-induced charges (the polarization direction here is away from the silicon surface) bring a negative surface po- tential which will affect the distribution of carders and charge collection in different electrodes significantly. The simulation results are expected to explain that the FeFET has a relatively good immunity to single event effect.
Bi0.9La0.1Fe0.95Mn0.05O3 (BLFMO) ferroelectric thin films were fabricated on Pt/Ti/SiO2/Si/ substrates by the sol-gel process at different pyrolysis temperatures. The mass loss of BLFMO powder was investigated by thermo gravimetry analyser (TGA), and the polycrystalline structure and smooth surface of BLFMO thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The remnant polarization (Pr) of the BLFMO films pyrolyzed at 420 ℃ is 21.2 μC/cm2 at the coercive field (Ec) of 99 kV/cm and the leakage current density is 7.1×10-3 A/cm2, which indicates that the BLFMO thin films display relatively good ferroelectric property at this temperature.
The alternation from bipolar to unipolar resistive switching is observed in perovskite La0.01Sr0.99TiO3 thin films. These two switching modes can be activated separately depending on the compliance current (Icomp) during the electroforming process: with a higher Icomp (5 mA) the unipolar resistance switching behavior is measured, while the bipolar resistance switching behavior is observed with a lower Icomp (1 mA). On the basis of I–V characteristics, the switching mechanisms for the URS and BRS modes are considered as being a change in the Schottky-like barrier height and/or width at the Pt/La-SrTiO3 interface and the formation and disruption of conduction filaments, respectively.
We use molecular dynamics simulation to calculate the thermal conductivities of(5, 5) carbon nanotube superlattices(CNTSLs) and defective carbon nanotubes(DCNTs), where CNTSLs and DCNTs have the same size. It is found that the thermal conductivity of DCNT is lower than that of CNTSL at the same concentration of Stone–Wales(SW) defects. We perform the analysis of heat current autocorrelation functions and observe the phonon coherent resonance in CNTSLs, but do not observe the same effect in DCNTs. The phonon vibrational eigen-mode analysis reveals that all modes of phonons are strongly localized by SW defects. The degree of localization of CNTSLs is lower than that of DCNTs, because the phonon coherent resonance results in the phonon tunneling effect in the longitudinal phonon mode. The results are helpful in understanding and tuning the thermal conductivity of carbon nanotubes by defect engineering.