Search results for "effect [finite size]"

Synthesis of Graphene Nanoribbons by Ambient-Pressure Chemical Vapor Deposition and Device Integration

2016

Graphene nanoribbons (GNRs), quasi-one-dimensional graphene strips, have shown great potential for nanoscale electronics, optoelectronics, and photonics. Atomically precise GNRs can be "bottom-up" synthesized by surface-assisted assembly of molecular building blocks under ultra-high-vacuum conditions. However, large-scale and efficient synthesis of such GNRs at low cost remains a significant challenge. Here we report an efficient "bottom-up" chemical vapor deposition (CVD) process for inexpensive and high-throughput growth of structurally defined GNRs with varying structures under ambient-pressure conditions. The high quality of our CVD-grown GNRs is validated by a combination of different …

Liquid-phase alkali-doping of individual carbon nanotube field-effect transistors observed in real-time

2011

The carbon nanotube (CNT) is known to be very sensitive to changes in its surrounding environment. Our study is on the effects of mild, liquid-phase alkali-doping on electronic transport in individual CNTs. We find clear and consistent reversal from p- to n-type behavior, with all seven investigated CNT field-effect transistors (FETs) retaining a similar ON/OFF ratio and subthreshold slope. We have also measured the realtime electronic response during liquid-phase doping, and demonstrate detection of alkali cations with a signal response that ranges over more than three orders of magnitude. The doping is fully reversible upon exposure to oxygen, and the doping cycle is repeatable. We also c…

CMOS-compatible nanoscale gas-sensor based on field effect

2009

The integration of a solid state gas sensor of the metal oxide sensor type into CMOS technology still is a challenge because of the high temperatures during metal oxide annealing and sensor operation that do not comply with silicon device stability. In the presence of an external electric field sensor sensitivity can be controlled through a change of the Fermi energy level and consequently it is possible to reduce the operation temperature. Based in this effect, a novel field effect gas sensor was developed resembling a reversed insulated : gate field effect transistor (IGFET) with the thickness of gas sensing layer in the range of the Debye length (L D ). Under these conditions the control…

Trajectory tracking for an Ultralight WIG

2007

In this paper we present our research about a particular ultralight WIG. We have carried out the design of a Flight Control System that has to fix the control variables trend through a non-linear mathematical model, because of the particular geometric and aerodynamic configuration of this WIG. So, the non-linear mathematical model design has to reproduce exactly the aircraft behaviour either OGE or IGE. In particular, through classical semi-empirical relations, analytical equations have been obtained in order to evaluate incidence variations, downwash and upwash angles due to the ground. In the present paper only longitudinal dynamic is considered, because of its peculiarity in WIG's aircra…

Espiritualidad en atención paliativa: Evidencias sobre la intervención con counselling

2015

ResumenLas necesidades espirituales, cuando son elaboradas de forma efectiva, ayudarán a la persona al final de la vida a encontrar significado, mantener la esperanza y aceptar la muerte. El counselling es una de las terapias más utilizadas para mejorar estas necesidades. El objetivo del presente trabajo es ofrecer evidencia sobre la eficacia de esta terapia para la mejora de la espiritualidad de los pacientes atendidos en diversos dispositivos de salud. Para conseguirlo, se llevó a cabo una intervención de tres semanas en 131 pacientes de atención domiciliaria y hospitalizados. Tenían una edad media de 70.61 años (DT = 11.17). El 51.1% eran hombres. Se evaluó la espiritualidad de los pacie…

Electrical and optical properties of Graphene Field-Effect Transistors (GFETs) fabricated on sapphire

Fabrication and characterization of graphene field effect transistors (GFET)

2015

Graphene is a flat monolayer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice. This peculiarity is responsible of extraordinary physical properties. Graphene exhibits a strong ambipolar field effect and thanks to its huge charge carrier mobility, graphene is a suitable material for high frequency Electronics. Graphene field effect transistors (GFET) for high frequency applications have recently received much attention and significant progress has been achieved in this area. GFETs have been already made by using pre-patterned metal or graphene nanoribbon (GNR) back-gates and hexagonal boron nitride as a dielectric spacer. Among the most employed techniques for the…

Fabrication and analysis of the layout impact in Graphene Field Effect Transistors (GFETs)

2016

In this work we focused on the analysis of Graphene Field Effect Transistor (GFET) microwave parameters dependence on geometries. In particular, a statistical, experimental investigation of the cut-off frequency (ft) dependency on both the gate-drain/source distance (Δ) and the gate length (Lg) was carried out. 24 GFET families on the same chip were fabricated, each one made of 10 identical (same geometry) devices. The analysis of the measured data shows that ft is both Δ and Lg dependent, and that there exists an optimal region in Δ and Lg design space.

Microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions

2016

Graphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and this feature, together with the high carrier mobility observed, makes graphene an interesting solution for high frequency electronics. In our work, we performed a statistical analysis in order to evaluate the microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions. In more detail, for the first time, we studied the behavior of the cut-off frequency (ft) and of the output impedance (Zout) at varying both the gate-drain/gate-source distance (Δ) a…

Impact of GFETs geometries on RF performances

2016

Graphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and the observed high carrier mobility makes graphene an interesting solution for high frequency electronics. In this work, we focused on the analysis of microwave parameters dependence on geometries in Graphene Field Effect Transistors (GFETs). In particular, a statistical, experimental investigation of the cut-off frequency (fT) and of the output impedance (Zout) dependency on both the gate-drain/source distance (Δ) and the gate length (Lg) was carried out. 24 GFET families wer…