A5076553166- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Semiconductor materials and interfaces
- Advanced Semiconductor Detectors and Materials
- Semiconductor Quantum Structures and Devices
- Surface and Thin Film Phenomena
- Semiconductor materials and devices
- Copper-based nanomaterials and applications
- Supramolecular Self-Assembly in Materials
- Ferroelectric and Piezoelectric Materials
- Classical Antiquity Studies
- Electron and X-Ray Spectroscopy Techniques
- X-ray Diffraction in Crystallography
- Thermography and Photoacoustic Techniques
- Supramolecular Chemistry and Complexes
- nanoparticles nucleation surface interactions
- Crystallization and Solubility Studies
- Reformation and Early Modern Christianity
- ZnO doping and properties
- Luminescence Properties of Advanced Materials
- Solid-state spectroscopy and crystallography
- Electronic and Structural Properties of Oxides
- Quantum and electron transport phenomena
- Dielectric properties of ceramics
- Molecular Junctions and Nanostructures
ETH Zurich
2024
University of Zurich
2022-2024
University of Oxford
2021-2022
Hewlett-Packard (United States)
2010
Philips (United States)
2009
Grand Valley State University
2009
Associated Universities, Inc.
2003
Brookhaven National Laboratory
2003
Durham University
1984-1993
King Saud University
1991-1992
An extensive experimental examination of conductivity glow curves and their analysis has been made on a variety CdS crystals. A large number analytical methods have used to evaluate trap depths capture cross sections. It is shown that it possible obtain consistent results determine whether retrapping occurs provided an procedure adopted produce isolated, non-overlapping, curves. Good agreement obtained between parameters calculated from (1) data (2) photoconductive decay.
A method of evaluating experimentally determined thermally stimulated current curves by a process successive approximation is described. The essentially one curve fitting and an excellent fit eventually obtained between the theoretical experimental curves. serves to determine electron-trapping parameters. technique can be used for two extreme cases trap emptying: emptying with no retrapping fast retrapping. illustrated its application some results from CdS crystals.
Self-assembly and molecular recognition are critical processes both in life material sciences. They usually depend on strong, directional non-covalent interactions to gain specificity make long-range organization possible. Most supramolecular constructs also at least partially governed by topography, whose role is hard disentangle. This makes it nearly impossible discern the potential of shape motion creation complexity. Here, we demonstrate that order can be assisted topography individual...
A thermodynamic analysis was made of the pseudobinary phase diagrams III–V semiconductor alloys, , and . The excess free energy mixing is expressed as where a parameter characteristic each system are mole fractions end components. This homologous series alloys showed consistent behavior in that all vs. composition plots were linear for both liquids solids. greater part solids appears to be entropy rather than enthalpy, indicating these materials freeze with local ordering or structure...
Negative magnetoresistance is observed at 4.2\ifmmode^\circ\else\textdegree\fi{}K in Cd-doped $p$-type GaAs, vapor deposited $n$-type and P-doped Ge. In GaAs prepared by Czochralski or horizontal-Bridgman techniques, samples with carrier concentrations less than about ${10}^{16}$ show negative which goes through a maximum fields 10 000 G becomes positive high fields. At greater there no clear indication of up to 20 G. The ratio longitudinal transverse the impurity conduction range function...
New strategies for synthesizing polyyne polyrotaxanes are being developed as an approach to stable carbyne "insulated molecular wires". Here we report active metal template route [3]rotaxanes, using dicobalt carbonyl masked alkyne equivalents. We synthesized two both with the same C28 dumbbell component, one a phenanthroline-based macrocycle and 2,6-pyridyl cycloparaphenylene nanohoop. The thermal stabilities of rotaxanes were compared that naked in decalin at 80 °C, nanohoop rotaxane was...
Conductivity glow curve experiments have shown that six major sets of electron traps can be found in cadmium sulphide crystals prepared this laboratory. Traps which lie 0.25 eV below the conduction band are associated with excess cadmium. These centres disappear when a crystal is irradiated white light at or near room temperature, while two new appear depths 0.41 and 0.83 eV. The process reversible, initial levels restored by heating 100°C dark. trap not sulphur-rich crystals. Experiments on...
GaAs grown in a horizontal Bridgman crystal growth apparatus to which oxygen has been added exhibits lower silicon content than that without oxygen. Material under additions of 10–20 Torr exhibits, at room temperature, carrier densities the 2–4×1015 cm−3 range and mobilities between 7500–8650 cm2 V−1 sec−1. Silicon concentrations computed from reaction 4Ga+SiO2 → 2Ga2O+Si are compared with electrical determinations donor spectroscopic reasonably good agreement. It is concluded suppression...
It is shown that the steep rise of current with accelerating field in a diode an oxide-coated cathode cannot be fully explained either by surface roughness or patch effect. This leads to theoretical treatment, based on existence space-charge zone immediately inside coating The charge this vary applied and density, certain parameters variation work function, thereby dependence emission strength, which combined normal Schottky effect effects partial space relationship between anode voltage are...
The extent of the influence that molecular curvature plays on self-assembly supramolecular polymers remains an open question in field. We began addressing this fundamental with introduction "carpyridines", which are saddle-shaped monomers can associate one another through π-π interactions and rotational translational movements restricted. topography displayed by led, previously, to assembly highly ordered 2D materials even absence strong directional such as hydrogen bonding. Here, we...
In this paper, the turbulent transport properties of ST40 hot ion plasmas are examined and fully predictive time evolving modelling a plasma pulse was performed. Understanding on spherical tokamaks (STs) is challenging due to their unique geometry characteristics. typically unstable scale Trapped Electron Modes (TEMs) Ubiquitous (UMs), driven from kinetic response trapped particles passing ions, electron Temperature Gradient (ETGs) at edge plasma. A comparison between linear modes...
Two compositions of BaTiO3 positive temperature coefficient resistance ceramics, prepared identically except for the fact that a small addition Mn (0.04 at. %) was made to one them, were studied. The samples sintered simultaneously in air at 1400 °C 1 h and then annealed 1200 ° 5 h, using muffle furnace. Room-temperature dielectric measurements audio- radio-frequency ranges confirmed has negligible effect on bulk resistance. Arrhenius plots resistivity vs 1/[Tε′m(T)] found give straight...
BaTiO3 positive temperature coefficient of resistance (PTCR) specimens were made from commercial which was mixed with 0.35 mol. % Ho2O3 to make it semiconducting and 0.07 MnCO3. After sintering at 1320 °C the samples annealed in batches 1220 for various periods between 0 5 h. The effect Mn studied by making direct comparison previous results obtained free but otherwise identical specimens. Room-temperature dielectric measurements audio radio frequency ranges revealed that had a negligible on...
The electrical conductivity and Hall coefficient of a variety single crystals zinc selenide have been measured. As-grown, undoped resistivity ( approximately 1012 Omega cm) which is too large for successful measurements to be made. However, after heat treatment at 850 degrees C in molten zinc, the sample reduced about 10-1 cm. samples are fairly heavily compensated. mobility free electrons 530 cm2 V-1 s-1 room temperature when optical mode scattering dominant mobility-limiting mechanism. At...
ABSTRACT Single crystals of cadmium sulphide can be activated to give high photo-conductive sensitivity in a variety ways. Experiment shows that containing non-stoichiometric excess the form sulphur vacancies are inherently unstable. Their photoconductivity decays under illumination and on exposure an ambient atmosphere oxygen. This instability eliminated by using activation treatment which does not produce vacancies. The photochemical effects heat oxygen number differently have been...
A long-standing question in the theory of photoconductivity semiconductor films is whether change conductivity can be attributed completely to a carrier density, or current amplification occurs through modulation barrier potentials. This studied chemically deposited lead sulfide by measuring fractional Hall coefficient, $\frac{\ensuremath{\Delta}{R}_{H}}{{R}_{H}}$, and resistivity, $\frac{\ensuremath{\Delta}\ensuremath{\rho}}{\ensuremath{\rho}}$, under illumination. The measurements were...
A technique is described for producing dislocation etch pits on (0001), (0001) and {1010} growth faces of cadmium sulphide crystals. Methods are also whereby the dislocations decorated by precipitation either gallium or copper. The strongest proof that formed where lines cut free surfaces provided (1) characteristic pattern after indentation; (2) densities in intersecting low-angle grain boundaries; (3) coincidence lines. Various other observations support main evidence.