Abstract:Evans D A, Roberts O R, Vearey-Roberts A R, Langstaff D P, Twitchen D J and Schwitters M 2007 Direct observation of Schottky to ohmic transition in Al-diamond contacts using realtime photoelectron spectroscopy Appl. Phys. Lett. 91 132114 doi:10.1063/1.2790779Real-time photoelectron spectroscopy and in situ electrical measurements have been applied to the formation of Al contacts on p-type diamond. At 294 K, an initially uniform Al film induces band bending in the diamond consistent with the measured (current-v… Show more
“…Other examples of the use of snapshot core level photoemission spectra to monitor changes in surface band bending on semiconductor surfaces are described elsewhere. 45,46 In addition, LEED measurements were also carried out in 50°C steps from RT to the highest heating temperatures. 2(a)-2(c)] is due to bulk oxygen, while the higher BE component (shifted to higher BE by 1.4 eV) is commonly attributed to surface hydroxyl groups.…”
Surface sensitive synchrotron x-ray photoelectron spectroscopy (XPS) and real-time in situ XPS were used to study the thermal stability of the hydroxyl termination and downward band bending on the polar surfaces of ZnO single crystals. On the O-polar face, the position of the Fermi level could be reversibly cycled between the conduction band and the band gap over an energetic distance of approximately 0.8 eV (similar to 1/4 of the band gap) by controlling the surface H coverage using simple ultrahigh vacuum (UHV) heat treatments up to 750 degrees C, dosing with H2O/H-2 and atmospheric exposure. A metallic to semiconductorlike transition in the electronic nature of the O-polar face was observed at an H coverage of approximately 0.9 monolayers. For H coverage less than this, semiconducting (depleted) O-polar surfaces were created that were reasonably stable in UHV conditions. In contrast, the downward band bending on the Zn-polar face was significantly more resilient, and depleted surfaces could not be prepared by heat treatment alone.preprintPeer reviewe
“…Other examples of the use of snapshot core level photoemission spectra to monitor changes in surface band bending on semiconductor surfaces are described elsewhere. 45,46 In addition, LEED measurements were also carried out in 50°C steps from RT to the highest heating temperatures. 2(a)-2(c)] is due to bulk oxygen, while the higher BE component (shifted to higher BE by 1.4 eV) is commonly attributed to surface hydroxyl groups.…”
Surface sensitive synchrotron x-ray photoelectron spectroscopy (XPS) and real-time in situ XPS were used to study the thermal stability of the hydroxyl termination and downward band bending on the polar surfaces of ZnO single crystals. On the O-polar face, the position of the Fermi level could be reversibly cycled between the conduction band and the band gap over an energetic distance of approximately 0.8 eV (similar to 1/4 of the band gap) by controlling the surface H coverage using simple ultrahigh vacuum (UHV) heat treatments up to 750 degrees C, dosing with H2O/H-2 and atmospheric exposure. A metallic to semiconductorlike transition in the electronic nature of the O-polar face was observed at an H coverage of approximately 0.9 monolayers. For H coverage less than this, semiconducting (depleted) O-polar surfaces were created that were reasonably stable in UHV conditions. In contrast, the downward band bending on the Zn-polar face was significantly more resilient, and depleted surfaces could not be prepared by heat treatment alone.preprintPeer reviewe
“…Finally, / 0 B decreased from 1.59 to 1.46 eV through the annealing at 600 K. Interfacial reactions, such as the formation of Al-C and Ti-C bonds at the diamond interface, have been observed above 500 K with similar time constants. 18,19 The formation of W-C bounds at the WC/p-diamond interface could be the origin of the / 0 B lowering. An alternative model to explain the decrease of / 0 B is the dissociation of oxygen atoms terminating the diamond surface.…”
The stabilization by vacuum annealing of tungsten carbide/p-diamond Schottky barrier diodes (SBDs) has been investigated. The Schottky barrier height (ϕB) and ideality factor (n), at high temperature, were consistently estimated by employing a vertical SBD structure. An exponential drop of ϕB in time at 600 K and its stabilization at 1.46 eV after 90 min were reported. The lowest n among SBDs examined was close to 1.0 at 600 K. A linear relation between ϕB and n in a statistical electrical characterization suggests a ϕB inhomogeneity.
“…9 Photoelectron-based methods have the required inherent nano-scale sensitivity but are rarely used as a real-time probe since the data acquisition time is usually prohibitive. [10][11][12] Using a combination of a bright synchrotron light source and multichannel electron detection, coupled to theoretical modeling, we have been able to apply this method in real time to reveal the evolving organization of molecules during the growth of thin organic semiconductor films on different semiconductor and metal substrates.…”
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confidence: 99%
“…Fast photoelectron spectroscopy probing both core and occupied valence states has been enabled using a direct electron counting multi-channel array detector coupled to a conventional hemispherical array detector. 12,17 Tunable synchrotron radiation in the soft x-ray region enables valence and core level electron spectra to be recorded during growth using a single incident photon energy. All accessible substrate and overlayer core levels and band edges were monitored sequentially to provide a direct and parallel probe of the changing chemical, a)…”
Post-deposition molecular rearrangement in thin organic films is revealed by in situ real-time photoelectron spectroscopy during organic molecular beam deposition. Agreement between real time spectroscopy and Monte Carlo modeling confirms the role of nearest-neighbor molecular attraction in driving a time-dependent morphology for oriented films of tin phthalocyanine (SnPc) on a range of substrates. The time-dependent molecular self-organization occurs over timescales comparable to the growth rates and is therefore an important factor in the degradation of thin films of organic semiconductors typically considered for the fabrication of multilayer semiconductor devices. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4775762]publishersversionPeer reviewe
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