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We presented an idea to increase the efficiency of the MoS2 solar cells with the special E-k relation of the intermediate band in MoS2 nanoribbon structures. From the calculations of armchair nanoribbon structures by the tight binding method, we found that the continuous surface states forming at the middle bandgap has the lowest energy states at X-valley. This dispersion relation will allow phonons to rapidly scatter electrons to the lower X valley of the intermediate band in pico-second scale. Simulations show that this will prevent electrons to be directly recombined with the holes in the Γ valley. After modelling the transition rates of photon absorption and emission with the solar spectrum, it shows a significant improvement of the short circuit current compared to the bulk MoS2 structures without intermediate bands.

The bandstructures of [110] and [001] Bi2Te3 nanowires are solved with the atomistic 20 band tight binding functionality of NEMO5. The theoretical results reveal: The popular assumption that all topological insulator wire surfaces are equivalent is inappropriate. The Fermi velocity of chemically distinct wire surfaces differs significantly which creates an effective in-surface confinement potential. As a result, topological insulator surface states prefer specific surfaces. Therefore, experiments have to be designed carefully not to probe surfaces unfavorable to the surface states (low density of states) and thereby be insensitive to the TI-effects., 2015 Applied Physics Letters

We report the characterization of the ceramic SrIn0.1Ti0.9O3 thin film grown by laser molecular-beam epitaxy. The lattice constant is determined to be 0.3948 nm, slightly larger than that of the SrTiO3 substrate. Hall measurement confirms that this film is a p-type semiconductor either below 92 K or above 158 K. X-ray photoemission spectroscopy study shows that the width of the valence band of the p-type SrIn0.1Ti0.9O3 film is narrower than that of the n-type SrNb0.1Ti0.9O3 film. There is a 0.35 eV difference in the Fermi energy level of the two films. The electronic state of the surface layer of the SrIn0.1Ti0.9O3 film is found to be different from that of its interior.

We studied the epitaxy of 10 mol % Nb:SrTiO3 on a SrTiO3(100) substrate under an interrupted pulsed-laser-deposition condition. By monitoring the recovery behaviors of reflection high-energy electron diffraction intensity and an optical reflectance difference signal from the growth surface, we observed that, at temperatures above 630 °C, the oxidation of an as-deposited Nb:SrTiO3 monolayer was achieved by the diffusion of oxygen vacancies in the monolayer into the substrate.

A series of BaTiO3−x (x=0, 0.07, 0.18, and 0.48) thin films with c-axis oriented tetragonal perovskite structures were epitaxially grown on SrTiO3 (100) and MgO (100) substrates by laser molecular-beam epitaxy under various oxygen pressures. The electrical conductivity of the deposited thin films increases with decreasing the oxygen pressure. A metallic conduction is observed in the oxygen most deficient BaTiO2.52 thin film whose oxygen content (2.52) and electrical resistivity (6.0×10−5 Ω cm) are both the minimum values among literature. An optical absorption peak is observed in each oxygen deficient BaTiO3−x thin film. The peak position shifts to lower energy, and the peak width becomes larger with decreasing the oxygen pressure. The influence of oxygen pressure on the electrical and optical properties in the reduced BaTiO3−x thin films is discussed.A series of BaTiO3−x (x=0, 0.07, 0.18, and 0.48) thin films with c-axis oriented tetragonal perovskite structures were epitaxially grown on SrTiO3 (100) and MgO (100) substrates by laser molecular-beam epitaxy under various oxygen pressures. The electrical conductivity of the deposited thin films increases with decreasing the oxygen pressure. A metallic conduction is observed in the oxygen most deficient BaTiO2.52 thin film whose oxygen content (2.52) and electrical resistivity (6.0×10−5 Ω cm) are both the minimum values among literature. An optical absorption peak is observed in each oxygen deficient BaTiO3−x thin film. The peak position shifts to lower energy, and the peak width becomes larger with decreasing the oxygen pressure. The influence of oxygen pressure on the electrical and optical properties in the reduced BaTiO3−x thin films is discussed.

The enhanced optical transmission through the annular aluminum metal with different number of concentric rings arranged in a long-range periodic structure on the silicon substrate is investigated. The measured transmission spectra demonstrate that the surface plasmon modes depend sensitively on the structural parameters of the metallic rings. The degenerate (1,0), (1,1), and (2,1) Al∕Si surface plasmon modes are determined by the long periodicity of the structure. The localized modes in cavities with different length can be observed in this structure as well. These phenomena suggest that both surface plasmons and localized cavity modes are excited within super unit cell.

The conductance of aniline trimers, pentamers, and heptamers has been measured in a molecular junction as a function of the oxidation state of the molecules by making measurements under electrochemical potential control. The effective electronic decay length is too small to be consistent with simple tunnel transport in the neutral molecule and is even smaller in the oxidized molecule. Thus these molecules can act as relatively high conductance links even in the absence of the interchain hopping required for metallic behavior.

Direct coupling of aminosilane molecules onto the plasma hydroxylated InN surface is demonstrated. By using synchrotron-radiation photoelectron spectroscopy, the authors have studied the surface chemical properties of (3-aminopropyl)trimethoxysilane coupled InN. They have also found that the positively charged amine terminal groups on the functionalized InN surface can be utilized to bind negatively charged Au colloids (10nm diameter) in aqueous solution. Combining with the existing bioconjugation techniques for Au colloids, this approach opens up the possibility of nanoparticle-biomolecular hybrid systems for chemical and biosensing using electronic devices based on surface-functionalized InN.