The following topics are discussed in the frame of the «bottom – up» approach of modern nanoelectronics: a super-brief but hopefully self-containing introduction to the Hamiltonian matrix whose eigenvalues tell us the allowed energy levels in the channel. However, the Hamiltonian describes an isolated channel and we can not talk about the steady-state resistance of an isolated chan-nel without bringing in the contacts and the battery connected across it. Non-equilibrium Green’s functions method in matrix presentation was initially formulated and applied to model transport problems for 1D and 2D conductors using a nearest neighbor orthogonal tight-binding model in the frame of the «bottom – up» approach of modern nanoelectronics. General method to account for electric contacts in Schrödinger equation to solve electron quantum transport problems is given. There are also discussed the elastic and spin dephasing modeling, account for non-coherent processes using Buttiker probe, 1D conductor with two and more scatterers, quantum interference, strong and weak localization, potential drop across scatterers, quantum oscillations in NEGF method without dephasing and with its account under phase and impulse relaxation regimes, destructive and constructive interference effects, four-component description of spin transport with account for dephasing and ending with discussion of quantum nature of classics including spin coherence and pseudo-spin formalism.
General issues of electronic conductivity and the causes for the current flow, role of electro-chemical potentials, Fermi functions, and Fermi window for conduction are discussed, as well as there given detailed description of the Landauer elastic resistor model, different transport regimes from ballistic to diffusion and in between, conductivity modes, and transmission coefficient in the frame of the «bottom – up» approach of modern nanoelectronics. Generalized model of electron transport in the linear response regime developed by R. Landauer, S. Datta, and M. Lundstrom with application to the resistors of any dimension, any size and arbitrary dispersion working in ballistic, quasi-ballistic or diffusion regime is summerized.
In summary, the Landauer equation for the conductivity describes the electron transport in the conductor from the very general positions. The conductivity is proportional to the fundamental constants q and h, which determine the quantum of conductance, associated with contacts. The conductivity depends on the number of modes of conductance and transmission coefficient, representing the probability that an electron with energy E injected by one contact to reach another contact. Conductivity we finally find by integrating the contributions from all modes of conduction. The equations valid for 1D, 2D and 3D conductors for ballistic nanoreactors as well as for massive conductors.
The theory of electrical conduction is developed in the framework of the “bottom – up” approach without invoking the concept of an external electric field generated by a potential difference applied to the conductor. Within the concept of «bottom – up» approach of modern nanoelectronics the diffusion-drift model of a current on the basis of the Boltzmann transport equation is described. There are also discussed the role of the external electric field beyond the linear response regime, field-effect transistor and saturation current, the role of conductor charging, the point and extended models of a conductor, the role of contacts, the model of p-n junctions, the generation of a current in a conductor with asymmetric contacts.
In summary, we conclude, that when a band structure is given, number of modes can be evaluated and, if a model for the mean-free-pass for backscattering can be chosen, then the near-equilibrium transport coefficients can be evaluated. Next, the new generalized Ohm’s law was formulated and used which provides a quite different view of resistivity in terms of the number of modes per unit area and the mean-free-path. Finally, the transport model given is equally well applied either to nanoresistors or as well to micro- and macroconductors made of any kind of materials.
Non-equilibrium Green’s functions method is applied to model transport problems for 1D and 2D uniform conductors using the nearest neighbor orthogonal tight-binding approximation in the frame of the «bottom – up» approach of modern nanoelectronics.
First of all we discuss the construction of the contact matrices of self-energies. The basic idea is that infinitely long conductor described by the Hamiltonian [H] is replaced by a conductor of the finite length described by the matrix [H + Σ1 + Σ2] with the open boundary conditions at the ends meaning “good” contacts, which do not create the reflected streams at its ends. Further we discuss 1D ballistic conductor, a 1D conductor with a single scattering center, then 2D conductor is modeling and explanation is given to the steplike dependence of the transmission coefficients over the energy, and finally there is given the representation of 2D/3D conductor in the form of parallel 1D conductors, which is not only physically correct but also extremely useful in interpreting experimental data.
In summary the physical adequacy of the Huckel approach is stated in the framework of the method of nonequilibrium Green’s functions.
Non-equilibrium Green’s functions method in matrix presentation is given with application to transport of electrons in quantum regime.
Basic topics of spintronics such as spin valve, interface resistance due to mode mismatch, spin potentials, non-local spin voltage, spin moment and its transport, Landau – Lifshitz – Gilbert equation, and explanation on its basis why a magnet has an “easy axis”, nanomagnet dynamics by spin current, polarizers and analyzers of spin current, diffusion equation for ballistic transport and current in terms of non-equllibrium potentials are discussed in the frame of the «bottom – up» approach of modern nanoelectronics.
General questions of electronic conductivity, conductivity modes, n- and p-type conductors and graphene are discussed in the frame of the «bottom – up» approach of modern nanoelectronics
Thermoelectric phenomena of Seebeck and Peltier, quality indicators and thermoelectric optimization, ballistic and diffusive phonon heat current are discussed in the frame of the «bottom – up» approach of modern nanoelectronics.
Current generation with the use of electrochemical potentials and Fermi functions is discussed in the frame of the bottom – up approach of modern theoretical and applied nanoelectronics.
Elastic resistor model, ballistic and diffusion transport and new formulation of the Ohm’s law are discussed in the frame of the bottom – up approach of modern nanoelectronics.
Theoretical basis to compute graphene band structure and density of states in the simplest π–electronic approximation with derivation of the Dirac – Weyl equantions are given including results with an account for π–π–overlap and neighbours up to 3rd order. The necessity of accounting for graphene σ-core is stated. DFT/LDA, GGA and EHT-SCF approaches are shortly described. Corresponding computational observations including ab initio results are given in the next communication.
The first-principle methods for calculating the charging molecular energies and charge stability diagram of the benzene molecule single-electron transistor under the Coulomb blockade regime were applied using the densityfunctional theory for modeling molecular properties and continuum model to describe SET environment as well as a self-consistent approach to treat the interaction between the molecule and the SET environment.