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This paper reports the optimization of voltage controlled resistive switching devices in terms of device and circuit level parameters in a memristor-based circuit in order to demonstrate profound non-linear characteristics for high performance NVM applications. The pinched hysteresis loop has been correlated to the different stages of formation and rupture of conductive filaments in memristors. A qualitative study of the VTEAM model has also been presented. The memristor circuit has been simulated for varying device and circuit level parameters and options to optimize the circuit to achieve high degree of power-aware non-linearity in the characteristics of the memristor have been demonstrated in this paper. The effect of window functions on the non-linear behavior of memristors has been presented towards the end of the paper.

Resistive random-access memory (RRAM) is a non-charge-based two-terminal non-volatile memory device. It is a promising candidate for usage in high radiation applications such as medical devices, aircraft, and space. The impact of radiation affects the resistance of RRAM. The resistance depends on the dimensions of the conductive filament. In this work, we have analyzed the impact of radiation on RRAM resistance with respect to the length and width of the conductive filament (CF). For our simulations, radiation is modeled as a double exponential current pulse (DECP). Different values of DECP are injected to mimic different radiation doses. Our simulations on the RRAM device demonstrate that high radiation dose affects the device performance in terms of low resistance state (LRS) and high resistance state (HRS). There is no distinction between LRS and HRS due to high radiation dose.

Electron transport through a few-donor cluster flanked by acceptors is studied by first-principles and semi-empirical simulations in gated Si-nanowire transistors with n+electrostatically-doped source/drain. Local density-of-states spectra are probed by electrical characteristics at room temperature for clarifying modifications induced by acceptor-atoms on the energy states of the few-donor cluster. It is found that acceptor-atoms located between the few-donor cluster and the leads mainly shift the cluster potential, introducing a minor distortion to its energy spectrum. The results change only weakly as the acceptor-atoms are moved towards the Si nanowire surface, and systematically depend on the number of acceptors.

High temperature aluminium alloys containing iron and cerium additions have promising mechanical properties, particularly with regard to thermal stability. Development of these alloys has been possible because of advances in rapid solidification technology. The advantage of rapid solidification is that it produces extended solid solubility or a high volume fraction of strengthening dispersoids depending on the cooling rate. To retain the microstructural advantages of rapid solidification, it has generally been thought necessary to process these alloys at the lowest possible temperature. The present work indicates that for optimum strength levels this is correct but that the greater homogeneity of microstructure produced by higher processing temperature leads to improved ductility and toughness. The present investigation was undertaken to find suitable extrusion processing conditions for two rapidly solidified high temperature aluminium alloys having the compositions Al–6·7Fe–5·9Ce and Al–6·2Fe–5·9Ce–1·63Si (all wt-%). Silicon was added to Al–Fe–Ce in an attempt to form the Al12(Fe,Ce)3Si phase, which if formed might improve the thermal stability of the alloy (similar to the Al12(Fe,V)3Si phase in the Al–Fe–V–Si system). Both the alloys were extruded in the temperature range 400–500°C at a constant extrusion ratio of approximately 10:1 and ram speed of 3 mm s-1. The room temperature mechanical properties of all the extrudates were measured for both alloys and the values obtained were compared with those for other high temperature aluminium alloys such as Al–5Cr–2·2Zr and Al–8·3Fe–4·8Zr. High temperature tensile properties were measured for extrudates processed at 400 and 450°C. The results obtained for the low temperature (400°C) extrudate were found to be satisfactory when compared with US Air Force Materials Laboratory (AFML) goals for high temperature aluminium alloys. Attempts have been made to explain the properties on the basis of the microstructures of the extrudates, which were characterised using transmission and scanning electron microscopy and X-ray diffraction.MST/1615

Aluminium alloys containing additions of iron and cerium are among the alloys being developed as potential replacements for titanium based alloys for moderately high temperature applications. Development of these alloys is possible using rapid solidification technology, which results in a very fine distribution of dispersoids in the aluminium matrix. The microstructures of two rapidly solidified high temperature alloy powders of composition (wt-%) Al–6·7Fe–5·9Ce (alloy A) and Al–6·2Fe–5·9Ce–1·63Si (alloy B) have been characterised using transmission electron microscopy and the results are explained on the basis of some of the major solidification parameters, such as nucleation undercooling and recalescence. It was observed that most of the powder particles in the +10 to -20 µm size range contained both microcellular and cellular regions, which could be explained in terms of an initial large undercooling followed by recalescence. The decomposition of the powder microstructure after exposing the powders to temperatures of 350, 420, and 500°C for 1 h was investigated using transmission electron microscopy. This work was complemented by phase identification studies using X-ray diffraction. The equilibrium precipitates Al13Fe4, Al8Fe2Si, and Al3FeSi were detected in the powder microstructure of alloy B, whereas Al13Fe4precipitates were detected in alloy A after high temperature exposure (500°C).MST/1571