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Rectangular graphene nanoribbons with two contacts have been studied extensively as parts of several nanoelectronic devices. L-shaped and T-shaped graphene nanoribbons received a little or no attention until now. In this letter, we present computations of the conductance of L-shaped graphene nanoribbons with two contacts and of T-shaped graphene nanoribbons with tree contacts. We used tight-binding Hamiltonians and non-equilibrium Green's functions to compute their conductance. In L and T-shaped nanoribbons electrons are initially transported along a zigzag-edged nanoribbon, and then the direction of their motion changes by 90O and are transported along an armchair-edged nanoribbon. Our results show that this change in direction of motion results in a zero-conductance region that extents about 0.25 eV below and above the Fermi level. This zero conductance region is large enough to cause current switching and, because of this, L and T-shaped graphene nanoribbons can be used as building blocks for logic gates.

The design and simulation of a single-electron 2-4 decoder using a novel single electron circuit simulation tool named single-electron circuit simulator (SECS), is presented in this paper. In single electron circuits bits of information are represented by the presence or absence of single electrons at conducting or semiconducting islands. SECS utilizes the Monte Carlo method and the change in free-energy of the whole circuit determines the tunnel rates of possible tunnel events, providing thus a real time simulation of any arbitrary single-electron circuit. Furthermore, SECS is using the SPICE interface for schematic capture. SPICE models of single-electron circuit structures have been developed and, therefore, SECS can also be used for the design and simulation of hybrid microelectronic-single-electron circuits.

A nanoelectronic single-electron Control–Not gate is presented in this paper. Bits of information are represented by the presence or absence of single electrons at conducting islands. The logic operation of the gate is verified using simulation, whereas the stability of its operation is analyzed using Monte-Carlo method.

Non-linear filters are large family of filters used in signal and image processing. They have found numerous applications such as in digital image restoration, speech processing and coding, digital TV applications, etc. In this paper, two binary non-linear filters, the three-point median filter and the 2×2-pixel morphological opening filter are designed using nanoelectronic single-electron circuitry. In single-electron circuits bits of information are represented by the presence or absence of single electrons at conducting islands. The two nanoelectronic filters are simulated using a Monte Carlo technique and their correct and stable logical operation is confirmed.

A single-electron universal Control–Control-Not gate (CCN gate) is presented in this paper. Bits of information are represented by the presence or absence of single-electrons at conducting islands. The logic operation of the CCN gate as well as its XOR, AND, NAND and NOT operation is verified using simulation. The stability of its universal operation is analysed using a Monte Carlo method. Stability analysis using free energy diagrams and stability plots verify the correct and stable operation of the gate.

The design of a nanoelectronic single-electron analog to digital (A to D) converter is presented. By taking advantage of the Coulomb blockade effect, the conversion of the analog input to a digital signal is obtained directly without the use of reference voltages, counters or other auxiliary circuitry. The operation of the A to D converter is simulated and the electron transport in the circuit is analyzed. The stability of the single-electron A to D converter circuit is studied and its stable operation is shown. The main result of this research work is that single-electron A to D converters are simple, stable and can be fabricated.

A single-electron half-adder is presented in this paper. Bits of information are represented by the presence or absence of single electrons at conducting islands. The logic operation of the half-adder is verified using simulation, whereas the stability of its operation is analysed using the Monte Carlo method.

The design of a single-electron AND gate with three inputs is presented for the first time in this paper. The operation of this gate has been simulated using a well-known single-electron circuit simulator. Furthermore, the stability of its operation has been studied by constructing the free-energy history diagram, and by constructing and analyzing the corresponding three-dimensional stability plot, using Monte Carlo simulation. Simulation has verified the correct and stable operation of the gate.

A new single-electron circuit implementing the logic function XOR is presented in this paper. The logic gate proposed consists of five tunnel junctions, two capacitors and four islands. The operation of this gate is analysed using Monte Carlo simulation. The simulation results show that the gate operates in stable regions.