Resistive memories are promising candidates for replacing current nonvolatile memories and realize storage class memories. Moreover, they have memristive properties, with many discrete resistance levels and implement artificial synapses. The last years researchers have demonstrated RRAM chips used as accelerators in computing, following the new in-memory and neuromorphic computational approaches. Many different metal oxides have been used as resistance switching materials in MIM structures. Understanding of the switching mechanism is very critical for the modeling and the use of memristors in different applications. Here, we demonstrate the bipolar resistance switching of silicon nitride thin films using heavily doped Si and Cu as bottom and top-electrodes respectively. Next, we dope nitride with oxygen in order to introduce and modify the intrinsic nitride defects. Analysis of the current-voltage characteristics reveal that under space-charge limited conditions and by setting the appropriate current compliance, the operation condition of the RRAM cells can be tuned. Furthermore, resistance change can be obtained using appropriate SET/RESET pulsing sequences allowing the use of the devices in computing acceleration application. Impedance spectroscopy measurements clarify the presence of different mechanisms during SET and RESET. We prove through a customized measurement set-up and the appropriate control software that the initial charge-storage in the intrinsic nitride traps governs the resistance change.

Studies of quantum computer implementations suggest cellular quantum computer architectures. These architectures can simulate the evolution of quantum cellular automata, which can possibly simulate both quantum and classical physical systems and processes. It is however known that except for the trivial case, unitary evolution of one-dimensional homogeneous quantum cellular automata with one qubit per cell is not possible. Quantum cellular automata that comprise two qubits per cell are defined and their evolution is studied using a quantum computer simulator. The evolution is unitary and its linearity manifests itself as a periodic structure in the probability distribution patterns.

Graphene nanoribbons (GNRs) are the most important emerging Graphene structures for nanoelectronic and sensor applications. GNRs with perfect lattices have been extensively studied, but fabricated GNRs contain lattice defects the effect of which on their electronic properties has not been studied extensively enough. In this paper, we apply the Non-Equilibrium Green's function (NEGF) method combined with tight-binding Hamiltonians to investigate the effect of lattice defects on the conductance of GNRs. We specifically study, butterfly shaped GNRs, which operate effectively as switches, and have been used in CMOS-like architectures. The cases of the most usual defects, namely the single and double vacancy have been analytically examined. The effect of these vacancies was computed by placing them in different regions and with various numbers on GNR nano-devices, namely edges, main body, contacts and narrow regions. The computation results are presented in the form of energy dispersion diagrams as well as diagrams of maximum conductance as a function of the number of lattice defects. We also present results on the defect tolerance of the butterfly shaped GNR devices.

Graphene is a biocompatible material that can be incorporated safely into living tissue. This property makes graphene an ideal material for bioelectronics applications. The main obstacle for using graphene as a material for bioelectronic circuits is the lack of a bandgap, which results in noneffective current switching. Here, we use rectangular L-shaped graphene nanoribbons as a building block for graphene logic gates. Electrons are initially transported along the zigzag-edged nanoribbon and then the transport direction changes by 90°, resulting in transport along the armchair edge. Our computations showed that electron scattering because of this change in the direction causes the appearance of a pseudobandgap, which is large enough for logic operations. This pseudobandgap appears as a zero-conductance region for electron energies near the Fermi level. We propose an and, an or, and a not logic gate and use tight-binding Hamiltonians and nonequilibrium Greens functions to show that these designs can reproduce effectively the desired logic operations.