The temperature dependence of the band gap of semiconducting carbon nanotubes was measured for ten different nanotube species. The unprecedented effectiveness in avoiding the effect of external strain, or any other effects originating from the surrounding environment, lead to an accurate measurement of the band gap temperature dependence, giving fundamental insight into the nanotube electron-ph...

Self-consistent numerical calculation and photoluminescence (PL) measurements have been used to investigate the temperature dependence of the optical Stark e ect in n-doped GaAs/AlGaAs single asymmetric quantum wells (SAQWs), grown by molecular beam epitaxy. In the low-temperature regime (5 to 40 K) a remarkable blue shift (9.8 meV) is observed in the PL peak energy, as the optical excitation i...

by means of first principles calculations we show that both rutile and anatase phases of bulk tio2 doped by s, se or pb can display substantial decreasing in the band gap (up to 50%), while doping by zr does not sizably affect the band-gap value. moreover, the absorption edge is shifted (up to 1 ev) to the lower energy range in the case of tio2 doped by s or pb that opens a way to enhancing of ...

We have performed high-resolution photoluminescence spectroscopy on silicon crystals with different isotopic composition and investigated the effects of this composition on the indirect electronic band gap and phonon energies. From the relative energy shift of the indirect electronic band gap between two crystals of different isotopic composition, the zero-point renormalization energy of that e...

Zn0.97TM0.03O (TM = Co, Fe) thin films were deposited onto glass substrates by the sol–gel method and the effects of transition metals substitution on structural and optical properties of ZnO films were investigated. The X-ray diffraction patterns revealed that the films have wurtzite structure. Optical transmittance of the films was recorded in the range of 200 -800 nm wave length and the band...

li2ni8o10 and limn2o4 nanoparticles as cathode materials of lithium ion battery, were successfully synthesized using lithium acetate, nickel and manganese acetate as li, ni and mn sources and stearic acid as a complexing reagent. the structure of the obtained products were characterized by ft-ir and xrd. the shape, size and distribution of the li2ni8o10 and limn2o4 nanoparticles were observed b...

In the present work, Bi2S3 nanostructures have been synthesized with the aid of thioglycollic acid (TGA) a solvent, capping agent, and sulfide source in the presence of ultrasonic method. The as-synthesized products were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM), and photoluminescence (PL) spectroscopy. The band gap ...

It has been well-established that single layer MX2 (M = Mo, W and X = S, Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap multilayer counterparts. In few-layer MX2, there are two valleys along the Γ-K line with similar energy. There is little understanding on which of the two valleys forms the conduction band minimum (CBM) in this thi...