We report scanning tunneling microscopy and scanning tunneling spectroscopy (STS) measurements of monolayer and bilayer WSe_{2}. We measure a band gap of 2.21±0.08  eV in monolayer WSe_{2}, which is much larger than the energy of the photoluminescence peak, indicating a large excitonic binding energy. We additionally observe significant electronic scattering arising from atomic-scale defects. U...

This paper uses X-ray absorption spectroscopy to study the electronic structure of the high-k gate dielectrics including TM and RE oxides. The results are applicable to TM and rare earth (RE) silicate and aluminate alloys, as well as complex oxides comprised of mixed TM/TM and TM/RE oxides. These studies identify the nature of the lowest conduction band d* states, which define the optical band ...

We use microprobe angle-resolved photoemission spectroscopy (microARPES) to separately investigate the electronic properties of CuO2 planes and CuO chains in the high temperature superconductor, YBa2Cu4O8. For the CuO2 planes, a two-dimensional (2D) electronic structure is observed and, in contrast to Bi2Sr2CaCu2O8+delta, the bilayer splitting is almost isotropic and 50% larger, which strongly ...

Nanowire band-to-band tunneling field-effect transistors ͑TFETs͒ are simulated using the Wentzel– Kramers–Brillouin ͑WKB͒ approximation and an atomistic, full-band quantum transport solver including direct and phonon-assisted tunneling ͑PAT͒. It is found that the WKB approximation properly works if one single imaginary path connecting the valence band ͑VB͒ and the conduction band ͑CB͒ dominates the tunne...

Scanning tunneling microscopy and spectroscopy are used to study InGaP/GaAs heterojunctions with InGaAs-like interfaces. Band offsets are probed using conductance spectra, with tip-induced band bending accounted for using 3-dimensional electrostatic potential simulations together with a planar computation of the tunnel current. Curve fitting of theory to experiment is performed. Using an InGaP ...

Nanostructures of CaF2 and CaF1 on Si~111! are used to demonstrate a chemical imaging method for insulators. Chemical sensitivity is achieved in scanning tunneling microscopy via a sharp drop of the tunneling current for bias voltages below the conduction-band minimum. This imaging method has a spatial resolution of better than 1 nm and distinguishes different oxidation states. A resonance is f...

For bulk liquid helium the bottom of the conduction band (V0) is above the vacuum level. In this case the surface of the liquid represents an electronic surface barrier for an electron to be injected into the liquid. Here we study the electronic conduction band for doped helium droplets of different sizes. Utilizing an electron monochromator, the onset of the (H2O)2- ion yield corresponding to ...

It is numerically shown that the groundstate ofthe Friedel problem (consisting of a conduction band and a d­ resonance), occupied with (n+ I) electrons, can be written as If/ = (Aoo+Bd*) rr=1 o~Po, where ail represents a localized conduction electron state, d* is the Friedel resonance state and TI~=1 a7,po is a Slater determinant of n single electron states it7, (po is the vacuum state). The 07...

Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potentia...