Search results for "Semiconductor"
showing 10 items of 974 documents
Optical Fibre, Local Measurement Systems For Ships
1987
Modern ships are more and more fully equipped with auxilliary control and supervising sys-tems. These systems, in turn, are more and more frequently built with the aid of fibre optics. Fibre optics ensures proper reliability of such a system in a harsh marine environment. This environment includes: marine climate containing salt spray, mechanical vibrations and shocks, electromagnetic and magnetic interferences, changing temperatures etc. All of these harmful reactions may influence the system /worst case marine environment/ during a single sailing cruise. We will consider here the worst case environment for a marine-grade fibre optic system.
Visible light active self-cleaning materials based on porphyrin-sensitised titanium dioxide
2017
Starting from second half of last century, nanostructured semiconductors have had a crucial function in the material science because of their wide application field going from renewable energy to organic/hybrid electronics up to photocatalysis. Among those materials, titanium dioxide is probably the most used because of some important characteristics like the chemical/mechanical stability, environmental sustainability, its low cost and versatility. Indeed, it has been successfully employed as photo- and electro-active component in electronic devices as well as photocatalytic agent1 in water de-pollution application. Interestingly and importantly together, titanium dioxide may also be applie…
Universal charts for optical difference frequency generation in the terahertz domain
2010
We present a universal and rigorous approach to study difference frequency generation in the terahertz domain, keeping the number of degrees of freedom to a minimum, through the definition of a suitable figure of merit. The proposed method relies on suitably normalized charts, that enable to predict the optical-to-terahertz conversion efficiency of any system based on wave propagation in quadratic nonlinear materials. The predictions of our approach are found to be in good agreement with the best experimental results reported to date, enabling also to estimate the d22 nonlinear coefficient of high quality GaSe.
300°C SiC Blocking Diodes for Solar Array Strings
2009
Silicon Carbide 300V-5A Ni and W Schottky diodes with high temperature operation capability (up to 300°C) have been fabricated. This paper reports on the stability tests (ESA space mission to Mercury, BepiColombo requirements) performed on these diodes. A DC current stress of 5A has been applied to these diodes at 270°C for 800 hours. These reliability tests revealed both, degradation at the Schottky interface (forward voltage drift) and at the diode top surface due to Aluminum diffusion (bond pull strength degradation). The use of W as Schottky metal allows eliminating the forward voltage drift producing stable metal–semiconductor interface properties. Nevertheless, SEM observations of the…
Towards an AMTEC-like device based on non-alkali metal for efficient, safe and reliable direct conversion of thermal to electric power
2018
Alkali Metal ThermoElectric Converters directly convert heat into electric energy and have promising applicability in the field of sustainable and renewable energy. The high theoretical efficiency, close to Carnot's cycle, the lack of moving parts, and the interesting operating temperature range drive the search for new materials able to ensure safe and reliable operation at competitive costs.The present work focuses on the design of a non-alkali metal based cell and on the fabrication of a testing device to validate the design work. The selection of a new operating fluid for the cell improves durability, reliability and safety of the device. Finally, we discuss possible applications to alr…
Size control of InAs∕InP(001) quantum wires by tailoring P∕As exchange
2004
The size and emission wavelength of self-assembled InAs∕InP(001) quantum wires (QWrs) is affected by the P∕As exchange process. In this work, we demonstrate by in situ stress measurements that P∕As exchange at the InAs∕InP interface depends on the surface reconstruction of the InAs starting surface and its immediate evolution when the arsenic cell is closed. Accordingly, the amount of InP grown on InAs by P∕As exchange increases with substrate temperature in a steplike way. These results allow us to engineer the size of the QWr for emission at 1.3 and 1.55 μm at room temperature by selecting the range of substrate temperatures in which the InP cap layer is grown.
Impedance analysis of perovskite solar cells: a case study
2019
Metal halide perovskites are mixed electronic-ionic semiconductors with an extraordinary rich optoelectronic behavior and the capability to function very efficiently as active layers in solar cells, with a record efficiency surpassing 23% nowadays. In this work, we carry out an impedance spectroscopy analysis of two perovskite solar cells with quite distinct optical and electrical characteristics, i.e. MAPbI3 and CsPbBr3-based devices. The main aim of the analysis is to establish how, regardless the inherent complexity of the impedance spectrum due to ionic effects, information like ideality factors, recombination losses and the collection efficiency can be qualitative and quantitatively as…
Crystalline-Size Dependence of Dual Emission Peak on Hybrid Organic Lead-Iodide Perovskite Films at Low Temperatures
2018
In this work, we have investigated the crystalline-size dependence of optical absorption and photoluminescence emission of CH3NH3PbI3 films, which is necessary to identify the potential practical applications of the gadgets based on perovskite films. This study was carried out at low temperatures to minimize the extra complexity induced by thermal effects. The purpose was to clarify the origin of the dual emission peak previously reported in the literature. We found that the grain size is responsible for the appearance or disappearance of this dual emission on CH3NH3PbI3 at low temperatures, whereas we have inferred that the thickness of the perovskite layer is a much more important factor …
Extended Validation of Dynamic Irreversible Thermoporation: A Novel Thermal Process for Microbial Inactivation
2015
A novel thermal treatment for microorganism inactivation, characterized by a very rapid temperature increase (up to 30°C/s) and a low final temperature (up to 65°C) maintained for a relatively short holding time, has been recently presented and tested by the authors, showing microbial load reduction greater than 5 log units against several common bacteria and yeasts. With the aim of extending the possible use of the new thermal treatment to a wider microorganisms class, in this work the dynamic irreversible thermoporation (DIT) treatment was further tested on a well-known thermoresistant strain, the Enterococcus hirae: The results of these new experimental tests confirmed the reliability of…
Electrical conductivity as a state indicator for the start-up period of anaerobic fixed-bed reactors.
2016
The aim of this work was to analyse the applicability of electrical conductivity sensors for on-line monitoring the start-up period of an anaerobic fixed-bed reactor. The evolution of bicarbonate concentration and methane production rate was analysed. Strong linear relationships between electrical conductivity and both bicarbonate concentration and methane production rate were observed. On-line estimations of the studied parameters were carried out in a new start-up period by applying simple linear regression models, which resulted in a good concordance between both observed and predicted values. Electrical conductivity sensors were therefore identified as an interesting method for monitori…