Photoemission spectroscopy

About: Photoemission spectroscopy is a research topic. Over the lifetime, 10821 publications have been published within this topic receiving 250888 citations. The topic is also known as: photoelectron spectroscopy & PES.

Fermi-Level Pinning and Chemical-Structure of Inp-Metal Interfaces

Abstract: We have used soft x‐ray photoemission spectroscopy (SXPS) to investigate the dependence of Fermi‐level pinning on chemical structure at InP–metal interfaces. SXPS core level spectra of Al, Ti, Ni, Au, Pd, Ag, and Cu on UHV‐cleaved InP(110) surfaces reveal evidence for semiconductor outdiffusion, metal indiffusion, metal‐anion bonding and metal‐cation alloying. Corresponding Fermi‐level movements indicate a range of pinning positions at significantly different energies within the n‐type InP band gap. These results demonstrate that the Schottky barrier heights depend sensitively on changes in interface chemical bonding and diffusion, which strongly affect the type of electrically active sites and interfacial layers formed.

Understanding reflectance anisotropy: Surface-state signatures and bulk-related features in the optical spectrum of InP ( 001 ) ( 2 × 4 )

Abstract: A detailed analysis based on first-principlescalculations with self-energy corrections is combined with photoemission spectroscopy to determine the origin of features observed in reflectance anisotropy spectroscopy ~RAS! at semiconductor surfaces. Using the InP(001)(2 34) surface as a model case we obtain quantitative agreement between slab calculations and low-temperature RAS measurements. We find the contributions to the anisotropy signal related either directly to surface states or to transitions between surface perturbed bulk wave functions. Our results demonstrate the high sensitivity of RAS to the surface structure and chemistry and show that the absorption processes causing the anisotropy signal take place in the uppermost few atomic layers of the substrate.

Photon-stimulated desorption and other spectroscopic studies of the interaction of oxygen with a titanium (001) surface

Abstract: Synchrotron radiation at the Synchrotron Ultraviolet Radiation Facility at the National Bureau of Standards has been employed to study the adsorption of oxygen on a Ti(001) surface using photon-stimulated desorption (PSD), electron-stimulated desorption (ESD), and ultraviolet photoemission spectroscopy (UPS). The dominant ESD and PSD products observed for oxygen exposures greater than one langmuir are ${\mathrm{O}}^{+}$ ions having a most probable kinetic energy of about 3 eV. The photon energy dependence of the PSD ion yield is similar to the major features of the constant final-state secondary-electron yield although there are some differences in detail. This similarity is consistent with the ${\mathrm{O}}^{+}$ desorption being initiated by the production of a Ti $3p$ core hole as suggested by the Knotek-Feibelman Auger decay mechanism. The dependence of the ${\mathrm{O}}^{+}$ ion yield on oxygen exposure and surface temperature is compared with UPS and work-function measurements. These data indicate that surface oxidation occurs at temperatures as low as 90 K and that at least a fraction of the surface oxide is electronically similar to the maximal valency compound Ti${\mathrm{O}}_{2}$.

Transition from electron accumulation to depletion at InGaN surfaces

Abstract: The composition dependence of the Fermi-level pinning at the oxidized (0001) surfaces of n-type InxGa1−xN films (0⩽x⩽1) is investigated using x-ray photoemission spectroscopy. The surface Fermi-level position varies from high above the conduction band minimum (CBM) at InN surfaces to significantly below the CBM at GaN surfaces, with the transition from electron accumulation to depletion occurring at approximately x=0.3. The results are consistent with the composition dependence of the band edges with respect to the charge neutrality level.