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The instability mechanisms of passivated and non-passivated low-temperature polycrystalline silicon thin film transistors (LTPS TFTs) under various bias stress conditions have been investigated. Irrespective of plasma treatment, the degradation was more severe under negative gate bias stress than that under positive gate bias stress. This could be due to Fowler–Nordheim tunneling electron induced impact ionization. For hot carrier stress, TFTs with NH3 plasma treatment degraded more severely than those without plasma treatment. This might be attributed to collapsing of weak Si–H bonds in NH3-plasma passivated devices. For the high current stress, it showed the opposite results against hot carrier stress. [Copyright &y& Elsevier]

Abstract: The TiO2 nanofibers and nanoparticles are prepared by electrospinning and molten salt method, respectively. The materials are characterized by X-ray diffraction scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and a thermal analysis. The SEM and TEM studies showed that fibers were of average diameter ∼100nm and composed of nanocrystallites of size 10–20nm. Electrochemical properties of the materials are evaluated using cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy. Cyclic voltammetric studies show a hysteresis (ΔV) between the cathodic and the anodic peak potentials for TiO2 nanofibers and nanoparticles (sizes ∼15–30nm) are in the range, 0.23–0.30V and a redox couple Ti4+/3+ around ∼1.74/2.0V. Electrochemical cycling results revealed that the TiO2 nanofibers have lower capacity fading compared to that of the nanoparticles. The capacity fading for 2–50 cycles was ∼23% for nanofibers, which was nearly one-third of that of corresponding nanoparticles (∼63%). We discussed the effect of particle size on hysteresis and cycling performance of TiO2 nanoparticles. Impedance analysis of TiO2 nanofibers and nanoparticles during first discharge cycle is analyzed and interpreted. [Copyright &y& Elsevier]