Search results for "schottky"
showing 10 items of 109 documents
Semiconducting properties of passive films and corrosion layers on weathering steel
2020
Abstract Anodic films were grown on Weathering Steel by potentiostatic polarization in slightly alkaline solution. The photoelectrochemical results reveal that they are n-type iron oxide with Eg = 2.0 eV. Rust layer grown by atmospheric corrosion are n-type semiconductors with a band gap higher than that estimated for the anodic film attributed to the formation of γ-lepidocrocite. The electrochemical impedance spectra allow to evidence that rust layers have a higher conductivity with respect to anodic films due to the presence of highly doped iron oxide layers. The use of Mott-Schottky theory to model the dependence of oxide capacitance as function of potential is critically discussed.
Effect of alloying elements on the electronic properties of thin passive films formed on carbon steel, ferritic and austenitic stainless steels in a …
2014
The influence of alloying elements on the electrochemical and semiconducting properties of thin passive films formed on several steels (carbon steel, ferritic and austenitic stainless steels) has been studied in a highly concentrated lithium bromide (LiBr) solution at 25 °C, by means of potentiodynamic tests and Mott Schottky analysis. The addition of Cr to carbon steel promoted the formation of a p-type semiconducting region in the passive film. A high Ni contentmodified the electronic behaviour of highly alloyed austenitic stainless steels.Mo did notmodify the electronic structure of the passive films, but reduced the concentration of defects.
Assessment on the use of the amorphous semiconductor theory for the analysis of oxide films
2015
Abstract Although the theory of Schottky barrier in amorphous semiconductors is generally accepted, the limits of validity of such theory have not yet been explored. The classic semi-analytical solution is obtained under the constraint of constant electronic density of states (DOS) distribution in the mobility gap. In order to take into account the presence of a DOS variable in energy, a semi-empirical corrective power law was introduced in this paper. It is shown that the equations derived for thick films maintain their validity also in the case of thin films, provided that the space charge region width remains lower than 70% of the whole film thickness. A new expression based on the use o…
Electronic cooling and hot electron effects in heavily doped silicon-on-insulator film
2004
The influence of carrier concentration in silicon-on-insulator film on the thermal characteristics of semiconductor and performance of the superconductor-semiconductor-superconductor micro-coolers have been investigated at sub kelvin temperatures. The overheating of the lattice in heavily doped silicon film must be taken into account in the analysis of electron-phonon coupling experiment and operation of the cooler device. The heat flow between electrons and phonons in heavily doped silicon films is found to be proportional to T6, which is in accordance with theoretical prediction for dirty limit. Increasing the doping level in the semiconductor considerably increases both the efficiency of…
AMORPHOUS SEMICONDUCTOR-ELECTROLYTE JUNCTION. A NEW INTERPRETATION OF THE IMPEDANCE DATA OF AMORPHOUS SEMICONDUCTING FILMS ON METALS.
1986
On the basis of the theory of amorphous semiconductor Schottky barrier an equivalent electrical circuit of the amorphous oxide film/electrolyte interface is proposed.—The analytical expressions for the equivalent conductance and capacitance of the barrier are reported in the hypothesis of a constant density of states within the mobility gap.—According to this model, the semiconducting properties and the impedance behaviour at different frequencies of anodic oxide films on Niobium are interpreted by taking into account the amorphous nature of the films.—An explanation for the anomalous behaviour of the Mott-Schottky plots usually observed with amorphous anodic oxide films is presented.—The p…
<title>Changes in the temperature dependence of the dielectric constant in irradiated antiferroelectric thin films</title>
2003
A model describing the changes of the Curie-Weiss temperature in lead-zirconate thin films under neutron irradiation is proposed. The Curie-Weiss temperature in the irradiated material decreases which is connected to charges caused by neutron irradiation. The charges located near the surfaces due to Schottky effect and in the bulk of the film results in different rates of the Curie-Weiss temperature decreases with neutron fluence. However the influence of the Schottky layers seems to be more pronounced. Satisfactory agreement between the theoretical results and the experimental data is obtained for different neutron fluences.© (2003) COPYRIGHT SPIE--The International Society for Optical Eng…
Dynamic response of thin-film semiconductors to AC voltage perturbations
2012
A theoretical treatment of a Schottky barrier dynamic response is developed on the basis of a general model of a semiconductor with thickness comparable in length to the space charge region width. It is shown that, when the space charge region approaches the metal/semiconductor interface, the electric field at this interface, induced by the charge accumulated on the metal, becomes significant with respect to the electric field induced by the charge accumulated on the semiconductor. Under this condition, the total capacitance of the Schottky barrier becomes independent of the polarization potential and tends to the value ε/L, like in a pure dielectric insulator. The term thin film is intende…
First laser cooling of relativistic ions in a storage ring
1990
The first successful laser cooling of ions at relativistic energies was observed at the Heidelberg TSR storage ring. A $^{7}\mathrm{Li}^{+}$-ion beam of 13.3 MeV was oberlapped with resonant copropagating and counterpropagating laser beams. The metastable ions were cooled from 260 K to a longitudinal temperature of below 3 K and decelerated by several keV. The longitudinal velocity distribution was determined by a fluorescence method. After laser cooling a strongly enhanced narrow peak appeared in the Schottky noise spectrum in addition to the uncooled ion distribution.
Formation and Rupture of Schottky Nanocontacts on ZnO Nanocolumns
2007
In this paper, the electrical transport and mechanical properties of Pt/ZnO Schottky nanocontacts have been studied simultaneously during the formation and rupture of the nanocontacts. By combining multidimensional conducting scanning force spectroscopy with appropriated data processing, the physical relevant parameters (the ideality factor, the Schottky barrier height, and the rupture voltage) are obtained. It has been found that the transport curves strongly depend on the loading force. For loading forces higher than a threshold value, the transport characteristics are similar to those of large-area Schottky contact, while below this threshold deviations from strictly thermionic emission …
Study of Passive Films Formed on AISI 316L Stainless Steel in Non-Polluted and Underwater-Volcano-Polluted Seawater
2014
This work studies the semiconducting behavior of passive films formed on AISI 316L (UNS S31603) in two different sea-water solutions, non-polluted and polluted, collected from the volcano of El Hierro Island. Polarization measurements, potentiostatic passivation tests, electrochemical impedance spectroscopy, and capacitance measurements were performed. Results show that the polluted seawater worsens passivation kinetics. Additionally, passive films formed on AISI 316L stainless steel in polluted seawater have been found to be less protective than those formed in non-polluted seawater, showing a more defective structure, owing to the acidity of the polluted medium.