Analytical Modeling of Short-Channel Fully-Depleted Triple Work Function Metal Gate (TWFMG) SOI MESFET

Silicon - In this paper, a new structure: triple work function metal gate SOI MESFET, intended for integration into the deep-submicron CMOS technology, is proposed. The gate of the device consists...     

Ionization coefficient of monolayer graphene nanoribbon

A semi-analytical model for impact ionization coefficient of graphene nanoribbon (GNR) is presented. The model is derived by calculating probability of electrons reaching ionization threshold energy E_t and the distance travelled by electron gaining E_t. In addition, ionization threshold energy is semi-analytically modelled for GNR. During modelling, we justify our assumptions using analytical modelling and comparison with simulation. Furthermore, it is shown that conventional silicon models are not valid for calculation of ionization coefficient of GNR. Finally, the profile of ionization is presented using the proposed models and the results are compared with that of silicon.     

Effect of temperature on friction and wear behaviour of CuO–zirconia composites

Results of wear tests using an alumina ball sliding against 5 wt% copper oxide doped tetragonal zirconia polycrystalline (CuO-TZP) ceramics are reported as a function of temperature up to 700 °C. The specific wear rate and friction coefficient are strongly dependent on temperature. Below a critical temperature (T < 600 °C), CuO-TZP showed a high coefficient of friction as well as a high wear rate. This was ascribed to the formation of a rough surface, caused by brittle fracture and abrasive wear, based on observations by scanning electron microscopy (SEM), laser scanning microscopy (LSM) and X-ray photoelectron spectroscopy (XPS). However, above 600 °C a self-healing layer is formed at the interface and results in low friction and wear. The mechanism of layer formation and restoration is discussed and rationalized by onset of plastic deformation caused by a reduction reaction of CuO to Cu₂O at high temperatures.     

Non-prespecified Starting Depot Formulations for Minimum-Distance Trajectory Optimization in Patrolling Problem

In this paper, two new formulations are presented for trajectory optimization in the patrolling problem. It is assumed that the starting depot is not prespecified; an assumption that distinguishes the present work from the existing literature. A number of viewpoints are assigned to be visited in a certain sequence to minimize the total travel distance. The problem turns out to be a variant of the well-known Traveling Salesmen Problem (TSP), namely the Single depot multiple Traveling Salesmen Problem (mTSP). Comparisons between the commonly-used prespecified starting depot approach and the proposed formulations are performed and the efficacy of the results is presented through simulations. It is noted that by using the new approach, the total travel distance can be improved by an average of about 20 % compared to the case where the starting depot is prespecified, and by about 40 % in the worst-case scenario (in terms of the starting depot).     

A model for length of saturation velocity region in double-gate Graphene nanoribbon transistors

Length of saturation region (LVSR) as an important parameter in nanoscale devices, which controls the drain breakdown voltage is in our focus. This paper presents three models for surface potential, surface electric field and LVSR in double-gate Graphene nanoribbon transistors. The Poisson equation is used to derive surface potential, lateral electric field and LVSR. Using the proposed models, the effect of several parameters such as drain-source voltage, oxide thickness, doping concentration and channel length on the LVSR is studied.     

Influence of countersurface materials on dry sliding performance of CuO/Y-TZP composite at 600 °C

Dry sliding wear tests on 5 wt.% copper oxide doped yttria stabilized zirconia polycrystals (CuO–TZP) composite have been performed against alumina, zirconia and silicon nitride countersurfaces at 600 °C. The influences of load and countersurface materials on the tribological performance of this composite have been studied. The friction and wear test results indicate a low coefficient of friction and specific wear rate for alumina and zirconia countersurfaces at F = 1 N load (maximum Hertzian pressure ～0.5 GPa). Examination of the worn surfaces using scanning electron microscope/energy dispersive spectroscopy confirmed the presence of copper rich layer at the edge of wear scar on the alumina and zirconia countersurfaces. However, Si₃N₄ countersurface sliding against CuO–TZP shows a relatively higher coefficient of friction and higher wear at 1 N load condition. These results suggest that the countersurface material significantly affect the behavior of the third body and self-lubricating ability of the composite.     

Graphene nanoribbon field-effect transistor at high bias

Combination of high-mean free path and scaling ability makes graphene nanoribbon (GNR) attractive for application of field-effect transistors and subject of intense research. Here, we study its behaviour at high bias near and after electrical breakdown. Theoretical modelling, Monte Carlo simulation, and experimental approaches are used to calculate net generation rate, ionization coefficient, current, and finally breakdown voltage (BV). It is seen that a typical GNR field-effect transistor''s (GNRFET) breakdown voltage is in the range of 0.5 to 3 V for different channel lengths, and compared with silicon similar counterparts, it is less. Furthermore, the likely mechanism of breakdown is studied.     

Quantum confinement effect on trilayer graphene nanoribbon carrier concentration

In this study, one-dimensional vision of carrier movement based on the band structure of trilayer graphene nanoribbon in the presence of a perpendicular electric field is employed. An analytical model of ABA-stacked trilayer graphene nanoribbon carrier statistics as a fundamental parameter of field effect transistor (FET) in corporation with a numerical solution is presented in the degenerate and non-degenerate limits. The simulated results based on the presented model indicate that the model can be approximated by degenerate and non-degenerate approximations in some numbers of normalised Fermi energy. Analytical model specifies that carrier concentration in degenerate limit is strongly independent of normalised Fermi energy; however, in the non-degenerate limit, it is a strong function of normalised Fermi energy. The proposed model is then compared with other types of graphene. As a result, the developed model can assist in comprehending experiments involving trilayer graphene nanoribbon FET-based devices.