We report a simple biogenic-route to narrow the band gap of TiO2 nanocrystals for visible light application by offering a greener method. When an electrochemically active biofilm (EAB) was challenged with a solution of Degussa-TiO2 using sodium acetate as the electron donor, greyish blue-colored TiO2 nanocrystals were obtained. A band gap study showed that the band gap of the modified TiO2 nano...

The ambipolar random telegraph signal (RTS) (i.e., RTS in both hole conduction at negative gate biases and electron conduction at positive gate biases) is observed in an ambipolar carbon nanotube field-effect transistor (CNT-FET). Then, the ambipolar RTS is used to extract the small band gap of the SWNT. The determination of the small band gap CNT using RTS demonstrates a potentially high accur...

To clarify the nature of photonic band gaps, a series of calculations on two-dimensional photonic crystals is undertaken. Systems that possess a large gap for one polarization and no gap for the other polarization are analyzed. Two features of a photonic crystal that give rise to a large photonic band gap for each polarization, i.e., connectivity and concentration of the dielectric material, ar...

We use evolutionary algorithms to design photonic crystal structures with large band gaps. Starting from randomly generated photonic crystals, the algorithm yielded a photonic crystal with a band gap sdefined as the gap to midgap ratiod as large as 0.3189. This band gap is an improvement of 12.5% over the best human design using the same index contrast platform. © 2005 American Institute of Phy...

Layered heterostructures combining ordinary and negative refractive index materials are shown to display a new type of photonic band gap corresponding to zero (volume) averaged refractive index. Distinct from band gaps induced by Bragg scattering, the zero-n; gap is invariant upon a change of scale length and is insensitive to disorder that is symmetric in the random variable. A metallic struct...

Experiments are described on the prism-coupled excitation of surface electromagnetic waves in one-dimensional photonic band-gap arrays. The low loss of photonic band-gap materials leads to narrow angular reflectivity resonances and high surface fields. These attributes, coupled with the ability to engineer the optical properties of photonic band-gap arrays, suggest these materials as powerful r...

Ag2Te simultaneously shows high mobility and low thermal conductivity, however the relatively low band gap of 0.2 eV prevents it from achieving high thermoelectric figure of merit, zT, in the high temperature phase. In this study, the band gap of Ag2Te has been increased enabling a zT of unity by forming alloys and composites with PbTe, thereby demonstrating the importance of exploiting potenti...