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We investigated the phonon scattering effects on the transport properties of carbon nanotube devices with micron-order lengths at room temperature, using the time-dependent wave-packet approach based on the Kubo formula within a tight-binding approximation. We studied the scattering effects of both the longitudinal acoustic and the optical phonons on the transport properties. The conductance of semiconducting nanotubes is decreased by the acoustic phonon, instead of the optical phonon. Furthermore, we clarified how the electron mobilities of the devices are affected by the acoustic phonon.

We present calculations of field emission current using the first-principles recursion-transfer-matrix (RTM) method with nonlocal pseudopotentials. The original boundary condition of the RTM method is modified to express a constant electric field deep into a vacuum region. We analyze field emission from an Al atom adsorbed on a metallic electrode and show the microscopic distributions of the electron emission current and the potential barrier for the system.

Using the recursion-transfer-matrix (RTM) method combined with the non-equilibrium Green's function (NEGF) method and density-functional theory, we perform ab initio calculations for the electron transport of molecular wires bridged between electrodes. We present an effective potential of molecular wire under a finite bias voltage and discuss the phonon emission and local heating due to inelastic electron–phonon coupling effects. We find that it is strongly dependent on contact conditions. When the contacts to electrodes are bad, excitation phonon modes at contacts become dominant for the energy dissipation.

The energy distributions of the occupied surface states of GaAs(001) surfaces with several kinds of surface superstructure are measured using photoemission yield spectroscopy. The surfaces are prepared by molecular beam epitaxy. The surface states are found to change in both distribution and density depending on the surface superstructure and the surface preparation conditions. It is concluded that not all observed surface states originate ordered surface atomic structures.

Schottky barrier heights (SBH's) are measured by current-voltage and capacitance-voltage methods for both Al/n-GaAs and Al/p-GaAs contacts with several kinds of rare-earth metal (Sm) interlayers, which differ in thickness, composition, and distance from the GaAs surface. The SBH for each contact is found to decrease (increase) without diode degradation for n-type (p-type) GaAs, compared to ideal Al/GaAs and rare-earth metal/GaAs contacts. It is concluded that the final SBH is determined during the interface evolution, such as alloy formation, of these contacts. The SBH changes are discussed in connection with the anomalous diffusion found only for the contacts with a SBH change and are explained by the current SBH formation model proposed by Monch.