In this paper, we have studied the strain, band-edge, and energy levels of cubic InGaAs quantum dots (QDs) surrounded by GaAs. It is shown that overall strain value is larger in InGaAs-GaAs interfaces, as well as in smaller QDs. Also, it is proved that conduction and valence band-edges and electron-hole levels are size dependent; larger QD sizes appeared to result in the lower recombination...

In this work, nanostructured TiO2 and Cr-doped TiO2 thin films were deposited on glass substrate through sonochemical-chemical vapor deposition (CVD) method. The resulting thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy, and photoluminescence spectroscopy techniques. The TiO2 thin film has nanocubic morphology and ...

Multi-walled carbon nanotubes (MWCNT)-doped TiO2 thin films were synthesized by the dip-coating method. The obtained products were characterized by SEM, EDX, XRD, and UV-vis absorption spectroscopy. The XRD patterns showed the presence of anatase phase. Absorption spectrum of MWCNT-doped TiO2 revealed a red shift in the optical absorption edge due to carbon doping. The photocatalytic properties...

In this work, the irreversible processes in light heating of Silicon (Si) and Germanium (Ge) thin films are examined. Each film is exposed to light irradiation with radiative and convective boundary conditions. Heat, electron and hole transport and generation-recombination processes of electron-hole pairs are studied in terms of a phenomenological model obtained from basic principles of irrever...

We present an experimental investigation of optical spin orientation in colloidal CdS quantum dots (QDs) by a femtosecond laser pulse at room temperature. The spin carrier and its spin-generation process are clarified. Firstly, the observed spin signals of CdS QDs in time-resolved Faraday rotation measurements are shown to belong to electron carriers, by comparing the spin dephasing dynamics an...

TiO2 nanoparticles, as a photocatalyst for oxidation of dimethyl methylphosphonate (DMMP) as an organophosphorus simulant of chemical warfare agent, were prepared by using sol-gel method. The prepared nanoparticles were then modified with transition metals in order to decrease the electron-hole recombination and increase the photocatalytic activity. Transition metal ions including Pt...

Various types of 2% Cu-incorporated CdS (Cu:CdS) quantum dots (QDs) with very similar sizes have been prepared via a water soluble colloidal method. The locations of Cu impurities in CdS host nanocrystals have been controlled by adopting three different synthetic ways of doping, exchange, and adsorption to understand the impurity location-dependent relaxation dynamics of charge carriers. The ox...

The electroluminescence of p-i-n diodes with fully strained Si0.80Ge0.20 /Si(001) is dominated by radiative recombination in an electron–hole plasma. The recombination mechanisms and the band gap renormalization have been studied experimentally and by modeling. In order to minimize the influence of the SiGe/Si interface regions and thus to study the intrinsic behavior of strained SiGe, electrol...

Here n, p denote the electron, hole density, respectively Jn, Jp the electron, hole current, μ the related mobilities, R the recombination/generation. The Poisson equation relates the electrostatic potential u to the total charge density (D is the net doping concentration, ε is the dielectric permittivity). Contact models result in different boundary conditions. For existence and uniqueness (cl...

Organic-inorganic hybrid systems based on lead halide compounds have recently encountered considerable success as light absorbers in solid-state solar cells. Herein we show how fundamental mechanistic processes in mesoporous oxide films impregnated with CH3NH3PbI3 can be investigated by time resolved techniques. In particular, charge separation reactions such as electron injection into the tita...