Jackson S. Smith

Ab initio calculation of energy levels for phosphorus donors in silicon

The s manifold energy levels for phosphorus donors in silicon are important input parameters for the design and modeling of electronic devices on the nanoscale. In this paper we calculate these energy levels from first principles using density functional theory. The wavefunction of the donor electron’s ground state is found to have a form that is similar to an atomic s orbital, with an effective Bohr radius of 1.8 nm. The corresponding binding energy of this state is found to be 41 meV, which is in good agreement with the currently accepted value of 45.59 meV. We also calculate the energies of the excited 1s(T2) and 1s(E) states, finding them to be 32 and 31 meV respectively.

Electronic properties of delta-doped Si:P and Ge:P layers in the high-density limit using a Thomas-Fermi method

The Thomas-Fermi-Dirac (TFD) approximation and an spds tight binding method were used to calculate the electronic properties of a δ-doped phosphorus layer in silicon. This self-consistent model improves on the computational efficiency of “more rigorous” empirical tight binding and ab initio density functional theory models without sacrificing the accuracy of these methods. The computational efficiency of the TFD model provides improved scalability for large multi-atom simulations, such as of nanoelectronic devices that have experimental interest. We also present the first theoretically calculated electronic properties of a δ-doped phosphorus layer in germanium as an application of this TFD model.

Correlating the energetics and atomic motions of the metal-insulator transition of m1 vanadium dioxide

Materials that undergo reversible metal-insulator transitions are obvious candidates for new generations of devices. For such potential to be realised, the underlying microscopic mechanisms of such transitions must be fully determined. In this work we probe the correlation between the energy landscape and electronic structure of the metal-insulator transition of vanadium dioxide and the atomic motions occurring using first principles calculations and high resolution X-ray diffraction. Calculations find an energy barrier between the high and low temperature phases corresponding to contraction followed by expansion of the distances between vanadium atoms on neighbouring sub-lattices. X-ray diffraction reveals anisotropic strain broadening in the low temperature structure’s crystal planes, however only for those with spacings affected by this compression/expansion. GW calculations reveal that traversing this barrier destabilises the bonding/anti-bonding splitting of the low temperature phase. This precise atomic description of the origin of the energy barrier separating the two structures will facilitate more precise control over the transition characteristics for new applications and devices.

Electronic transport in Si:P delta-doped wires

Despite the importance of Si:P

Hubbard physics in the PAW GW approximation

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Ab initio electronic properties of monolayer phosphorus nanowires in silicon

-doped wires for modern nanoelectronics, there are currently no computational models of electron transport in these devices. In this paper we present a nonequilibrium Greens function model for electronic transport in a

An Ab Initio Description of the Mott Metal-Insulator Transition of M

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_{2}

-doped wire, which is described by a tight-binding Hamiltonian matrix within a single-band effective-mass approximation. We use this transport model to calculate the current-voltage characteristics of a number of

Vanadium Dioxide

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Electronic structure of tungsten-doped vanadium dioxide: from band to Mott insulator

-doped wires, achieving good agreement with experiment. To motivate our transport model we have performed density-functional calculations for a variety of