An investigation of the model of porous silicon in the form of periodic set of silicon nanowires has been carried out. The electronic energy structure was studied using a first-principle band method-the method of pseudopotentials (ultrasoft potentials in the basis of plane waves) and linearized mode of the method of combined pseudopotentials. Due to the use of hybrid exchange-correlation potent...

With the development of monochromators for transmission electron microscopes, valence electron energy-loss spectroscopy (VEELS) has become a powerful technique to study the band structure of materials with high spatial resolution. However, artefacts such as Cerenkov radiation and surface effects pose a limit for interpretation of the low-loss spectra; also the inelastic delocalisation restricts...

The spin density wave phase transition in chromium has been studied by angle-resolved photoemission on a (110) surface. The electronic band structure is shown to exhibit backfolding in the antiferromagnetic state. Direct spectroscopic evidence is obtained on the gradual opening of an energy gap at the Fermi level. The gap extends almost isotropically around the G point, its magnitude reaching 2...

A molecular exciton signature is established and investigated under different ambient conditions in rubrene single crystals. An oxygen-related band gap state is found to form in the ambient atmosphere. This state acts as an acceptor center and assists in the fast dissociation of excitons, resulting in a higher dark and photoconductivity of oxidized rubrene. The band gap state produces a well-de...

Zinc oxide (ZnO) is a promising wide band gap semiconductor. It has a direct energy band gap, Eg of 3.3eV at room temperature. ZnO can be alloyed with CdO and MgO to form the ternaries CdxZn1-xO and MgxZn1-xO, extending the direct energy band from 2.8eV to 4.0eV. Through proper doping, it also can be made transparent and conductive, piezoelectric, or ferromagnetic. ZnO based single crystal nano...

the research in the short-chain organic -conjugated molecules has become one of the most interesting topics in the fields of chemistry. these compounds have become the most promising materials for the optoelectronic device technology. the use of low band gap materials is a viable method for better harvesting of the solar spectrum and increasing its efficiency. the control of the band gap of th...

in the present study, co-zno and co-ni-zno nanoparticles were synthesized by sonochemical methods and the structural and optical properties were investigated through fourier transform infrared spectroscopy (ftir), uv-vis spectroscopy, field emission scanning electron microscopy (fe-sem), x-ray diffraction (xrd), and photoluminescence spectroscopy (pl) methods. morphology of nanoparticles obtain...

This paper describes synthesis of In2S3 nanoparticles by sonochemistry method and their application to enhance solar cells performance which In2S3 nanoparticles work as co-sensitizer for the first time. In2S3 is a narrow band gap semiconductor (2 eV) with conduction band higher than TiO2. Therefore it can transfer electron to the conduction band of TiO2. The effect of different parameters such ...

Cobalt oxide (Co3O4) nanorods were prepared by a simple co-precipitation method using ethanol solution of cobalt nitrate as precursor and cetyl trimethylammonium bromide (CTAB) as surfactant. Morphological properties of the nanoparticles were characterized. XRD measurement exhibited the structure of Co3O4 nanocrystals for annealed samples. The SEM ima...