1,721,125 research outputs found
Conferenze divulgative presso Scuole /Enti
No full textLe sfide dei nuovi materiali
(D. Cavalcoli, B. Fraboni)
Quali e quante sono le applicazioni dei nuovi materiali? Solo per citare alcuni esempi:
Lampadine a pellicola. Pellicole flessibili saranno in uso prima nei display dei telefonini ed
entreranno presto anche nelle case, in sostituzione delle normali lampadine. Energia solare.
La quantità di energia che arriva dal sole è circa 10000 volte il consumo globale di energia.
Come utilizzare al meglio questa enorme riserva energetica? Quali saranno i materiali che
miglioreranno l’efficienza e diminuiranno i costi dell’energia solare fotovoltaica?
Nanoelettronica. L’attuale microelettronica è in crisi... come potremo “aiutarla”? In che
modo la ricerca sta cercando di risolvere i problemi relativi all’eccessiva miniaturizzazione
dei dispositivi elettronici
Numerical modeling of current-voltage characteristics to extract transport properties of organic semiconductors
No full textThe current vs. voltage (I-V) characteristics of single crystal rubrene Organic Field-Effect Transistors (OFETs) and polycrystalline poly(p-phenylenevinylene) (PPV) films are modeled using the polaron transport theory presented in a previous work [A. F. Basile et al., J. Appl. Phys. 115, 244505 (2014)]. The model is first applied to rubrene OFETs, where transport is two-dimensional
and is confined near the interface between the insulator and the organic semiconductor. By considering the effect of image charges in the insulator and by assuming a constant intrinsic mobility, we reproduce both the positive and the negative temperature dependences of the channel mobilities
measured on OFETs having a gate dielectric and an air-gap insulator, respectively. In addition, we adapt this model to the three-dimensional transport in PPV films, characterized by effective mobilities which depend on temperature, charge density, and electric field. We show that the I-V
characteristics of these materials can be matched by the numerical solution of the Poisson and drift-diffusion equations assuming a constant intrinsic mobility. The polaron binding energy can account for the thermally activated behavior of the I-V characteristics and for the increase of the effective mobility at high applied voltages. Therefore, this model enables to extract the intrinsic transport parameters of organic semiconductors, independent of the device structure, and of the measurement conditions. VC 2014 AIP Publishing LLC
Correlation among structural, electrical, and deep-level properties of Fe centers implanted in InP
No full textThe Fe-related properties in high-temperature Fe implanted and annealed InP were studied by means of PIXE-RBS-channeling and correlated with the results of electrical (current-voltage) measurements. It is found that the point defect mobility, the concentration of substitutional Fe, and the resistivity of the implanted layer, all follow a similar temperature behavior. For annealing temperatures higher than 500degreesC semi-insulating behavior controlled by the Fe2+ deep levels is observed
"Electrical and optical properties of Si-doped InGaP layers grown by LP-MOVPE width TBAs and TBP"
No full textSurface Photovoltage Spectroscopy Analyses of Cd1-x ZnxTe
No full textCd1-xZnxTe alloys have been studied by Surface Photovoltage Spectroscopy (SPS) and Energy Dispersive Spectroscopy (EDS). The analyses of surface photovoltage spectra have been perfomed at near- and above- band gap energies.
Surface recombination effects on the surface photovoltage have been investigated. SPS analyses of Cd1-xZnxTe alloys with different surface conditions have shown that the surface recombination velocity significantly affects the SPS determination of the material band gap. Accounting for this and preparing the surfaces accordingly, SPS spectra of Cd1-xZnxTe samples have allowed an accurate determination of the optical band gap as a function of the Zn concentration, determined via EDS analyses. The local increases in the density of states associated with band structure features in Cd1-xZnxTe alloys have been investigated by SPS spectra in the above- band gap energy range
Electrical spectroscopy of high resistivity ion-implanted layers by current-voltage measurements
No full textWe report on a spectroscopic characterization of electrically compensated high resistivity Fe-implanted InP and GaInP by room temperature space-charge-limited-current measurements. This method results to be a reliable and powerful tool to obtain a quantification of the degree of compensation and the free carrier concentration in the samples, together with the activation energy and density of states distribution of the dominant majority carrier traps. Moreover, by correlating these results with temperature dependent electrical spectroscopy analyses, it is possible to obtain information on material parameters, such as the carrier mobility, not always easily accessible by direct measurements
Direct X-ray Photoconversion in Organic Flexible Thin Film Devices: Photoconductive Gain and High-Z Nanoparticle-doping
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