A5006467571- Organic Electronics and Photovoltaics
- Thin-Film Transistor Technologies
- Semiconductor materials and interfaces
- Conducting polymers and applications
- Semiconductor materials and devices
- Advanced Memory and Neural Computing
- Silicon and Solar Cell Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Atmospheric and Environmental Gas Dynamics
- Climate variability and models
- Semiconductor Quantum Structures and Devices
- Analytical Chemistry and Sensors
- Silicon Nanostructures and Photoluminescence
- ZnO doping and properties
- Nanowire Synthesis and Applications
- Molecular Junctions and Nanostructures
- Electron and X-Ray Spectroscopy Techniques
- Atmospheric chemistry and aerosols
- Advanced Thermodynamics and Statistical Mechanics
- Integrated Circuits and Semiconductor Failure Analysis
- Global Energy and Sustainability Research
- Organic Light-Emitting Diodes Research
- Organic and Molecular Conductors Research
- Ocean Acidification Effects and Responses
- Scientific Research and Discoveries
University of Algarve
2015-2024
University of Amsterdam
1992-2015
State Key Laboratory of Synthetic Chemistry
2008
University of Hong Kong
2007-2008
Chinese University of Hong Kong
2007
Institute of Nanostructured Materials
2004
Aarhus University
1997-2002
University of California, Berkeley
1995-1998
Polish Academy of Sciences
1994
Institute of Physics
1994
An investigation into the stability of metal-insulator-semiconductor (MIS) transistors based on α-sexithiophene is reported. In particular, kinetics threshold voltage shift upon application a gate bias has been determined. The follow stretched-hyperbola-type behavior, in agreement with formalism developed to explain metastability amorphous-silicon thin-film transistors. Using this model, quantification device possible. Temperature-dependent measurements show that there are two processes...
Band theory for inorganic materials versus hopping or percolation organics? conduction is contrasted with the more widely used and theories organic electronic (). These are generally of lower performance than their counterparts this often presented as justification a different mechanism. Here it reasoned that switching to mechanism not justified.
Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals silicon–dioxide matrix. This performed by comparing ultrafast photo-induced absorption transients at different pump photon energies below and above the threshold energy for this process. The average nanocrystal size approximately 5–6 nm, as inferred from photoluminescence Raman spectra. A carrier efficiency 190% measured photo-excitation 2.8 times optical bandgap nanocrystals, deduced their Germanium...
It is reported that the electrical instability known as bias stress caused by presence of trapped water in organic layer. Experimental evidence provided observation an anomaly occurring systematically at around 200K. This observed a variety materials, independent deposition techniques and remarkably coincides with phase transition supercooled water. Confined does not crystallize 273K but forms metastable liquid. behaves electrically charge trap, which causes instability. Below 200K finally...
The authors have examined the field effect behavior of nanocomposite transistors containing ZnO (zinc oxide) tetrapods or nanocrystals dispersed in a polymer matrix poly[2-methoxy,5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). electrical characteristics tetrapods/MEH-PPV composite devices exhibit an increase hole mobility up to three orders magnitude higher than MEH-PPV device.
The electronic conduction of thin-film field-effect-transistors (FETs) sexithiophene was studied. In most cases the transfer curves deviate from standard FET theory; they are not linear, but follow a power law instead. These results compared to models “variable-range hopping” and “multi-trap-and-release”. accompanying IV Poole-Frenkel (exponential) dependence on drain voltage. explained assuming huge density traps. Below 200 K, activation energy for found be ca. 0.17 eV. energies mobility...
The electron paramagnetic resonance spectrum of float-zone silicon recorded after implantation with protons contains a strongly temperature dependent signal from vacancy-type defect. displays monoclinic-I symmetry below 65 K and trigonal above 100 K. This change, together hyperfine splitting single proton, allows an unequivocal identification ${\mathrm{VH}}^{0}$, the neutral charge state vacancy containing hydrogen atom. striking similarity between properties ${\mathrm{VH}}^{0}$...
Abstract We investigate photoluminescence of Eu-related emission in a GaN host consisting thin layers grown by organometallic vapor-phase epitaxy. By comparing it with reference sample Eu-doped Y 2 O 3 , we find that the fraction Eu 3+ ions can emit light upon optical excitation is order 1%. also measure quantum yield and this to reach (~10%) (~3%) under continuous wave pulsed excitation, respectively.
Electron paramagnetic resonance measurements on float-zone silicon implanted with protons at \ensuremath{\sim}50 K followed by heating to room temperature have revealed two signals ${S1}_{a}$ and ${S1}_{b}$ belonging the $S1$ group of signals. both originate from defects spin $S=\frac{1}{2}$ monoclinic-I symmetry. The near-trigonal g tensors several sets ${}^{29}\mathrm{Si}$ hyperfine splittings all closely resemble those observed previously for $V{\mathrm{H}}^{0},$ neutral charge state...
Abstract An investigation into the stability of metal insulator semiconductor (MIS) transistors based on α ‐sexithiophene is reported. In particular kinetics threshold voltage shift upon application a gate bias has been determined. The follow stretched‐hyperbola type behavior, in agreement with formalism developed to explain metastability amorphous–silicon thin film transistors. Using this model, quantification device possible. Temperature‐dependent measurements show that there are two...
Energy exchange between closely packed semiconductor quantum dots allows for long-range transfer of electronic energy and enables new functionalities nanostructured materials with a huge application potential in photonics, optoelectronics, photovoltaics. This is illustrated by impressive advances quantum-dot solids based on nanocrystals (NCs) direct bandgap materials, where this effect has been firmly established. Regretfully, the (resonant) close-packed ensembles NCs remains elusive...
Transient capacitance methods were applied to the depletion region of an abrupt asymmetric n+−p junction silicon and unintentionally doped poly[2-methoxy, 5 ethyl (2′ hexyloxy) paraphenylenevinylene] (MEH-PPV). Studies in temperature range 100–300 K show presence a majority-carrier trap at 1.0 eV two minority traps 0.7 1.3 eV, respectively. There is indication for more levels which activation energy could not be determined. Furthermore, admittance data reveal bulk conduction 0.12 suggesting...
Planar capacitor structures based on granular films composed of nanometric ferromagnetic grains embedded in an insulating Al2O3 matrix can switch between a high-conductance and low-conductance state. The switching properties are induced by forming process. ON/OFF resistance ratio is as high 104 under electrical field only 15 kV/m. This resistive accompanied capacitive two well-defined voltage-independent states, behavior that not readily explained the filamentary type conduction.
We study the concepts of residence time vs. adjustment for carbon dioxide in atmosphere. The system is analyzed with a two-box first-order model. Using this model, we reach three important conclusions: (1) never larger than and can, thus, not be longer about 5 years. (2) idea atmosphere being stable at 280 ppm pre-industrial times untenable. (3) Nearly 90% all anthropogenic has already been removed from
In briefly annealed silicon samples implanted with hydrogen and deuterium an electron paramagnetic resonance spectrum is detected. It identified as arising from a molecule oriented in the 〈111〉 crystallographic direction located most probably at interstitial site. Such result consistent recent theoretical calculations predicting such orientation to be of lowest energy. addition, evidence obtained indicating that forms part more elaborate cluster.