Charge transport in organic materials as a function of carrier concentration is investigated. An analytical model of the concentration dependent obility based on the variable hopping range theory is formulated. This model is applied to analyze the discrepancy between the experimental obilities extracted from FETs and LEDs. The result shows that an exponential density of states (DOS) is a good a...

The possibility of ferromagnetic ordering is revisited in the band model. The coherent potential approximation decoupling has been used for the strong on-site Coulomb interaction. The driving forces towards the ferromagnetism are the on-site and inter-site molecular fields coming from different Coulomb interactions. Another driving force is the lowering of the kinetic energy with growing magnet...

An experiment is conducted to determine the effect of uni-axial strain on the superconducting and microscopic properties of bulk Nb3Sn. Methods of calculating the electron DOS are explored in order to investigate whether the strain sensitivity of the superconducting properties is correlated to changes in the electron density of states. Two different methods are developed to calculate the Sommer...

[1] We report the high-pressure thermoelastic and vibrational thermodynamic parameters for hexagonal close-packed iron (e-Fe), based on nuclear resonant inelastic X-ray scattering and in situ X-ray diffraction experiments at 300K. Long data collection times, high-energy resolution, and quasi-hydrostatic sample conditions produced a high-statistical quality data set that comprises the volume-dep...

We have developed a subgap density of states (DOS) model of amorphous In-Ga-Zn-O (a-IGZO) based on optical and electrical measurements. We study the optical absorption spectrum of the a-IGZO using UV-Vis spectroscopy. Together with the first-principles calculations and transient photoconductance spectroscopy from the literature, we determine that the valence band tail and deep-gap states are do...

We present an ab initio full-potential linearized augmented plane-wave (FLAPW) study of the structural and electronic properties of the two bulk unstable compounds FeSi (CsCl structure) and FeSi2 (CaF2 structure) which have recently been grown by molecular beam epitaxy on Si(111). We obtain equilibrium bulk lattice constants of 2.72 Å and 5.32 Å for FeSi and FeSi2, respectively. The density of ...

Inelastic neutron scattering was used to measure the phonon densities of states DOSs for pure V and solid solutions of V with 6 to 7at% of Co, Nb, and Pt, at temperatures from 10 K to 1323 K. Ancillary measurements of heat capacity and thermal expansion are reported on V and V-7at%Co and used to help identify the different sources of entropy. Pure V exhibits an anomalous anharmonic stiffening o...

Plasma waves in graphene field-effect transistors (FETs) and nano-patterned graphene sheets have emerged as very promising candidates for potential terahertz and infrared applications in myriad areas including remote sensing, biomedical science, military, and many other fields with their electrical tunability and strong interaction with light. In this work, we study the excitations and propagat...

Structural quantum confinement in long-channel thin silicon-on-insulator MOSFETs has been quantified using the temperature dependence of the subthreshold current. The results were compared with the shifts in the threshold voltage. Data were obtained from simulations after initial verification with experimental data. This study demonstrates that, with the temperature dependence of the subthresho...