We report, for the first time, about an intermediate band solar cell implemented with InAs/AlGaAs quantum dots whose photoresponse expands from 250 to ∼6000  nm. To our knowledge, this is the broadest quantum efficiency reported to date for a solar cell and demonstrates that the intermediate band solar cell is capable of producing photocurrent when illuminated with photons whose energy equals t...

Carbon nanotubes exhibit a variety of unique electrical, mechanical, magnetic, and optical properties that make them attractive for potential applications in nanotechnology. In this project the energy band structure of single-walled carbon nanotubes of arbitrary chirality is computed using a tight binding scheme that is generalized to include second nearest neighbor interactions. Plots of this ...

The electronic structure of single InSb quantum dots (QDs) with diameters between 3 and 7 nm was investigated using atomic force microscopy (AFM) and scanning tunneling spectroscopy (STS). In this size regime, InSb QDs show strong quantum confinement effects which lead to discrete energy levels on both valence and conduction band states. Decrease of the QD size increases the measured band gap a...

The promising photovoltaic activity of pyrite (FeS2) is attributed to its excellent optical absorptivity and earth abundance, but its band gap, 0.95 eV, is slightly lower than the optimum value of 1.3 eV. Here we report the first investigation of strained FeS2, whose band gap can be increased by ∼0.3 eV. The influence of uniaxial and biaxial strains on the atomic structure as well as the electr...

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...

We have investigated carrier relaxation and exciton recombination dynamics in ZnO/ZnMgO multiple quantum wells using femtosecond pump–probe techniques at room temperature. For a probe energy above the band gap, the hot carriers exhibit an effective relaxation by longitudinal optical phonon scattering with a cooling time of 700–850 fs. By detecting the emission near the band-gap, a longer decay ...

Cu-doped and undoped Lead Iodide crystals have been grown by gel technique. Then, thin films of Cu-doped and udoped Lead Iodide crystals have been deposited, of various thicknesses, successively by thermal evaporation technique. These thin films were characterized by XRD, Transmittance and Reflectance. The lattice parameters of thin films of Cu-doped and undoped, were well matching with the AST...

The basic optical properties and optical constants of the ionomer thin film have been investigated by means of transmittance and reflectance spectra. The real (n) and imaginary (k) parts of the complex refractive index and dielectric constant of the thin film were determined. The oscillator energy Eo, dispersion energy Ed and other parameters have been determined by the Wemple– DiDomenico metho...

InN films with free electron concentrations ranging from mid-10 to mid-10 cm have been studied using optical absorption, Hall effect, and secondary ion mass spectrometry. The optical absorption edge covers a wide energy range from the intrinsic band gap of InN of about 0.7 to about 1.7 eV which is close to the previously accepted band gap of InN. The electron concentration dependence of the opt...

The reliability performance of InxGa1−xAs n-type metal–oxide–semiconductor field-effect transistors with Al2O3 gate dielectric under positive-bias temperature instability stress is investigated systematically. A model of stress-induced border traps was proposed to interpret all charge pumping and I–V experimental results excellently. The stress-induced border traps include recoverable donor tra...