The variable range hopping theory, as formulated for exponentially localized impurity states, does not necessarily apply in the case of graphene with covalently attached impurities. We analyze the localization of impurity states in graphene using the nearest-neighbor, tight-binding model of an adatom-graphene system with Green's function perturbation methods. The amplitude of the impurity state...

Exploring long-range electron transport across protein assemblies is a central interest in both the fundamental research of biological processes and the emerging field of bioelectronics. This work examines the use of serum-albumin-based freestanding mats as macroscopic electron mediators in bioelectronic devices. In particular, this study focuses on how doping the protein mat with hemin improve...

Theoretical calculation and experimental measurement have shown that twin grain boundary (GB) of molybdenum disulphide (MoS2) exhibits extraordinary effects on transport properties. Precise transport measurements need to verify the transport mechanism of twin GB in MoS2. Here, monolayer molybdenum disulphide with a twin grain boundary was grown in our developed low-pressure chemical vapor depos...

For better understanding of the charge-transport mechanisms in perovskite manganites, along with colossal magnetoresistance ~CMR! materials, such as La12xSrxMnO3, we study systems with decreased content of Mn ions, such as single crystals of LaGa12xMnxO3 (0,x,0.5). The conductivity of all the systems in study can be described adequately with a nonadiabatic approximation of the hopping model wit...

Diffusion of moving particles in stationary disordered media is studied using a phenomenological mode-coupling theory. The presence of disorder leads to a generalized diffusion equation with memory kernels having power law long time tails. The velocity autocorrelation function is found to decay like t -(a/2+1), while the time correlation function associated with the super-Burnett coefficient de...

The electrical transport and chemical sensing properties of individual multisegmented Au-poly(3,4-ethylenedioxythiophene)(PEDOT)-Au nanowires have been investigated. Temperature dependent conductivity measurements show that different charge transport mechanisms influence these properties in two types of PEDOT nanowires. Charge transport in PEDOT/poly(4-styrenesulfonic acid) (PSS) nanowires is i...

The electronic structures of an entire segment of a DNA molecule were calculated in its single-strand and double-helix cases using the DFT method with an overlapping dimer approximation and negative factor counting method. The hopping conductivity of the segment was calculated by the random walk theory from the results of energy levels and wave functions obtained. The results of the single-stra...

We report the frequency-dependent conductivity of the manganite system La1−xSrxMnO3 (x ≤ 0.2) when approaching the metal-insulator transition from the insulating side. Results from low-frequency dielectric measurements are combined with spectra in the infrared region. For low doping levels the behavior is dominated by hopping transport of localized charge carriers at low frequencies and by phon...

The present work describes the preparation of nanocomposites in which the multiwall carbon nanotubes (MWCNT) have been mixed with conducting polypyrrole (PPy) via an in situ chemical oxidative preparation method. To reveal their structural, morphological and thermal properties, the composites have been characterized by x-ray diffraction, field emission scanning electron microscope, Fourier tran...

Dielectric impedance measurements of porous silicon within the frequency range of 50 Hz–1.0 MHz and temperature range of 298–798 K revealed three semicircles in a Cole–Cole plot when the temperature is raised to 773 K; they are thought to correspond to contributions from the grain interior, grain boundary, and electrode/film interface, respectively. The enhancement in conductivity by heating fo...