Search results for " Semiconductors"

Thin Films of Semiconductors for Flexible Solar Cells: Electrochemical Deposition and Characterization

2011

Fabbricazione elettrochimica e caratterizzazione di materiali nanostrutturati

2010

High accuracy Raman measurements using the Stokes and anti-Stokes lines

1997

We show that by measuring the separation between the Stokes and anti-Stokes peaks excited by two different laser lines we obtain a very precise determination of absolute phonon energies. The method is useful for measuring small changes of these energies with strain, temperature, laser power, etc. It doubles the changes and avoids the necessity of using the reference lines in the Raman spectra. The method can be applied for the determination of phonon deformation potentials, for the characterization of strained heteroepitaxial layers, and for micro-Raman analysis of strain in silicon integrated circuits. We give examples of phonon shifts in Si, Ge, GaAs, InAs, and GaP as a function of applie…

Luminescence properties of III-V multi-junctions solar cells

2012

The recent achievement of multi-junctions solar cells, based on III-V semiconductors, exceeding 43% efficiency, has stimulated a rapid growth of concentration photovoltaic (CPV) technology. The large efficiency of these cells is based on the matching between the semiconductors band gap and the solar spectrum and the capability of working under concentrated illumination, up to ~1000 suns. The research pays, therefore, attention to investigate in detail the mechanisms that affect the conversion efficiency, such as the non radiative losses that increase the cell temperature thus favoring the electron-hole (e-h) recombination. With the aim to clarify the performances of these III-V cells, here …

Research data supporting the paper "Tuning the effective spin-orbit coupling in molecular semiconductors"

2017

We here present the data underlying the paper "Tuning the effective spin-orbit coupling in molecular semiconductors" accepted at Nature Communications on 24 February 2017. For contributions of the authors to the data and experimental details, please refer to the original paper.

Effect of carrier transfer on the PL intensity in self-assembled In (Ga) As/GaAs quantum rings

2006

We present results concerning the carrier transfer between In(Ga)As quantum rings in a stacked multilayer structure, which is characterised by a bimodal size distribution. This transfer of carriers explains the observed temperature behaviour of diode lasers based on that kind of stacked layer structures. The inter-ring carrier transfer can be possible by phonon assisted tunnelling from the ground state of the smallring family towards the big-ring family of the bimodal size distribution. This process is thermally activated in the range 40–80 K.

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…

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 …

Les matériaux pour capteurs chimiques

2002

National audience; A chemical sensor is composed of one part supplying chemical reco gnition coupled to one transducingsystem. At the recognition origin, interaction with the target chemical species is oftwo types, either electronicexchange, or ionic exchange. Two large classes of materials that can supply recognition proceed: metals andsemiconductors giving rise to electronic exchange and ionic conducting materials giving rise to ionic exchan-ge. This paper is structured in tw o large parts, emphasizing on materi als inducing specific interactions:semiconductor materials (metallic oxides and molecular semiconductors) and ionic conductor materials.In each part will be presented nature of ma…

Preparation and characterisation of optical and optoelectronic devices based in two-dimensional semiconductors

2020

In the Materials Science field, two-dimensional materials have gained the scientific community attention in recent years. The change and the appearance of novel properties when their thickness is reduced to nanometric scale has special interest for its fundamental properties study for, from this base, the design and its implementation in devices. The wide variety of materials with the possibility of being exfoliated at the two-dimensional level opens the field to different applications, from optoelectronic devices, detection and sensing, energy storage, catalysis, medical applications and quantum information technologies, among others. This thesis gathers results in both directions: a funda…