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Tunnel Field-Effect Transistor
Published in Shubham Tayal, Abhishek Kumar Upadhyay, Deepak Kumar, Shiromani Balmukund Rahi, Emerging Low-Power Semiconductor Devices, 2023
Chandan Kumar Pandey, Saurabh Chaudhury, Neerja Dharmale, Young Suh Song
Nanowire transistors [17–22] were found to provide the flexibility of using an extensive variety of materials such as silicon, germanium, group III-V (GaN, InN, AlN, InP, GaAs, etc.) and II-VI (CdS, ZnS, CdSe, ZnSe) compound semiconductors, and semiconducting oxides (ZnO, In2O3, TiO2) as a channel in the form of a nanowire. The diameter of such semiconducting nanowires replacing the planner channel of a conventional MOSFET has been scaled to 0.5 nm. These nanowires have been found to exhibit ballistic conduction due to quantum confinement.
Carbon nanotube electronics and devices
Published in Michael J. O’Connell, Carbon Nanotubes Properties and Applications, 2018
This behavior is often called ballistic conduction, since electrons travel between two terminals without any scattering event (Figure 4.2a). Note that the resistance of a ballistic conductor is not zero, even though there is no scattering in the conduction channel and no backscattering for electrons exiting the conductor. The quantum resistance (or contact resistance, as it is sometimes called) originates from the mismatch between the large number of modes in the macroscopic contacts that the current is distributed over, and the few electronic modes (one-dimensional subbands) available in the one-dimensional conductor. The interested reader can find an excellent introduction to Landauer–Büttiker formalism in Datta’s book on electronic transport in mesoscopic systems.3
Surface engineering with Chemically Modified Graphene
Published in Craig E. Banks, Dale A. C. Brownson, 2D MATERIALS, 2018
Paul Sheehan, D. R. Boris, Pratibha Dev, S. C. Hernandez, Woo-Kyung Lee, Shawn Mulvaney, T. L. Reinecke, J. T. Robinson, Stanislav Tsoi, S. G. Walton, Keith Whitener
Another challenge in using 2D materials for surface engineering is the occasionally necessary tradeoff between desirable but incompatible chemical or physical properties. One example is the tradeoff between the coverage of functional groups on graphene and graphene’s conductivity. Electrons in pristine graphene famously exhibit ballistic conduction which can be a desirable device characteristic. However, this conductivity diminishes with increasing coverage of covalently attached functional groups.35, 103 For applications where chemical versatility and conductivity are both needed, one must choose a concentration of functional groups that is dense enough to perform the requisite chemical functions but not so dense that the device becomes overly resistive. In certain cases, this problem has been solved: non-covalent pyrene linkers to graphene use n-n stacking to allow for a high density of functional groups at the graphene surface while only minimally disturbing the band structure of graphene.104
Coupling Mesoscopic Boltzmann Transport Equation and Macroscopic Heat Diffusion Equation for Multiscale Phonon Heat Conduction
Published in Nanoscale and Microscale Thermophysical Engineering, 2020
W. Cheng, A. Alkurdi, P.-O. Chapuis
The tested configuration is reminiscent of the nanowire of rectangular cross-section deposited on top of a silicon substrate. This configuration has been considered in particular in the works by Mazumder et al. [11] and experimentally tested by groups in Boulder [29], Lyon [30], Purdue [31], Caltech [32], and MIT [33]. The wire undergoes either Joule self-heating due to the transverse flow of electrical current or is simply heated remotely in non-contact way as it absorbs partly light from an optical beam at a wavelength where the substrate is transparent. Here, we consider only steady state, in contrast to some of the experimental works. The wire is treated as fixed-temperature segment of length l on top of the domain. The size of the segment was varied, but we will mostly report the l = 200 nm case. This is close to the average MFP of silicon at room temperature, therefore the Knudsen number associated to the heat source is Kn ~ 1, thus ballistic conduction occurs around the thermal source. The domain is 100 µm large, but due to the adaptive mesh of current FEM solvers, for which the number of mesh elements does not scale steeply with the size, the cost of increasing the domain would not be important. Far from the heater, for instance at a distance larger than 50 times the MFP (~10 µm in our case), thermal conduction is dominated by diffusive conduction. Hence, the whole domain can be divided into two parts: a region where accounting for ballistic dissipation is required and another region where heat diffusion is sufficient.