اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدBallistic Graphene Nanoribbon MOSFETs: a full quantum real-space simulation study
55
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
A real-space quantum transport simulator for carbon nanoribbon (CNR) MOSFETs has been developed. Using this simulator, the performance of carbon nanoribbon (CNR) MOSFETs is examined in the ballistic limit. The impact of quantum effects on device performance of CNR MOSFETs is also studied. We found that 2D semi-infinite graphene contacts provide metal-induced-gap-states (MIGS) in the CNR channel. These states would provide quantum tunneling in the short channel device and cause Fermi level pining. These effects cause device performance degradation both on the ON-state and the OFF-state. Pure 1D devices (infinite contacts), however, show no MIGS. Quantum tunneling effects are still playing an important role in the device characteristics. Conduction due to band-to-band tunneling is accurately captured in our simulations. It is important in these devices, and found to dominate the off-state current. Based on our simulations, both a 1.4nm wide and a 1.8nm wide CNR with channel length of 12.5nm can outperform ultra scaled Si devices in terms of drive current capabilities and electrostatic control. Although subthreshold slopes in the forward-bias conduction are better than in Si transistors, tunneling currents are important and prevent the achievement of the theoretical limit of 60mV/dec.
قيم البحث
اقرأ أيضاً
We present an atomistic three-dimensional simulation of graphene nanoribbon field effect transistors (GNR-FETs), based on the self-consistent solution of the 3D Poisson and Schroedinger equation with open boundary conditions within the non-equilibriu
m Greens Function formalism and a tight-binding hamiltonian. With respect to carbon nanotube FETs, GNR-FETs exhibit comparable performance, reduced sensitivity on the variability of channel chirality, and similar leakage problems due to band-to-band tunneling. Acceptable transistor performance requires effective nanoribbon width of 1-2 nm, that could be obtained with periodic etching patterns or stress patterns.
Stimulated by recent advances in isolating graphene, we discovered that quantum dot can be trapped in Z-shaped graphene nanoribbon junciton. The topological structure of the junction can confine electronic states completely. By varying junction lengt
h, we can alter the spatial confinement and the number of discrete levels within the junction. In addition, quantum dot can be realized regardless of substrate induced static disorder or irregular edges of the junction. This device can be used to easily design quantum dot devices. This platform can also be used to design zero-dimensional functional nanoscale electronic devices using graphene ribbons.
We calculate quantum transport for metal-graphene nanoribbon heterojunctions within the atomistic self-consistent Schrodinger/Poisson scheme. Attention is paid on both the chemical aspects of the interface bonding as well the one-dimensional electros
tatics along the ribbon length. Band-bending and doping effects strongly influence the transport properties, giving rise to conductance asymmetries and a selective suppression of the subband formation. Junction electrostatics and p-type characteristics drive the conduction mechanism in the case of high work function Au, Pd and Pt electrodes, while contact resistance becomes dominant in the case of Al.
We report an experimental study of Cooper pair splitting in an encapsulated graphene based multiterminal junction in the ballistic transport regime. Our device consists of two transverse junctions, namely the superconductor/graphene/superconductor an
d the normal metal/graphene/normal metal junctions. In this case, the electronic transport through one junction can be tuned by an applied bias along the other. We observe clear signatures of Cooper pair splitting in the local as well as nonlocal electronic transport measurements. Our experimental data can be very well described by using a modified Octavio-Tinkham-Blonder-Klapwijk model and a three-terminal beam splitter model.
We investigate the electronic band structure of an undoped graphene armchair nanoribbon. We demonstrate that such nanoribbon always has a gap in its electronic spectrum. Indeed, even in the situations where simple single-electron calculations predict
a metallic dispersion, the system is unstable with respect to the deformation of the carbon-carbon bonds dangling at the edges of the armchair nanoribbon. The edge bonds deformation couples electron and hole states with equal momentum. This coupling opens a gap at the Fermi level. In a realistic sample, however, it is unlikely that this instability could be observed in its pure form. Namely, since chemical properties of the dangling carbon atoms are different from chemical properties of the atoms inside the sample (for example, the atoms at the edge have only two neighbours, besides additional non-carbon atoms might be attached to passivate unpaired covalent carbon bonds), it is very probable that the bonds at the edge are deformed due to chemical interactions. This chemically-induced modification of the nanoribbons edges can be viewed as an effective field biasing our predicted instability in a particular direction. Yet by disordering this field (e.g., through random substitution of the radicals attached to the edges) we may tune the system back to the critical regime and vary the electronic properties of the system. For example, we show that electrical transport through a nanoribbon is strongly affected by such disorder.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
