Self-similar transmission properties of aperiodic Cantor potentials in gapped graphene

We investigate the transmission properties of quasiperiodic or aperiodic structures based on graphene arranged according to the Cantor sequence. In particular, we have found self-similar behaviour in the transmission spectra, and most importantly, we have calculated the scalability of the spectra. To do this, we implement and propose scaling rules for each one of the fundamental parameters: generation number, height of the barriers and length of the system. With this in mind we have been able to reproduce the reference transmission spectrum, applying the appropriate scaling rule, by means of the scaled transmission spectrum. These scaling rules are valid for both normal and oblique incidence, and as far as we can see the basic ingredients to obtain self-similar characteristics are: relativistic Dirac electrons, a self-similar structure and the non-conservation of the pseudo-spin. This constitutes a reduction of the number of conditions needed to observe self-similarity in graphene-based structures, see D\'iaz-Guerrero et al. [D. S. D\'iaz-Guerrero, L. M. Gaggero-Sager, I. Rodr\'iguez-Vargas, and G. G. Naumis, arXiv:1503.03412v1, 2015]

Formalismo de cálculo de la movilidad de portadores en un pozo cuántico delta dopado (DQW).

Este artículo ofrece un esquema para el cálculo de la movilidad de electrones en una estructura de pozo delta dopado, a bajas temperaturas y para campos eléctricos aplicados no muy intensos. El análisis se hace para un sistema dopado tipo n , considerando una lámina de impurezas de silicio en una muestra de GaAs . Se tiene en cuanta explícitamente el carácter tridimensional de los estados electrónicos y de las magnitudes que se miden – en lugar de realizar aproximaciones en que se reduzcan las dimensiones del sistema – , lo que facilita la ejecución del cálculo. Se exponen los resultados de otros esquemas utilizados y se dan las fórmulas que se emplearán para comprobar y comparar nuestros cálculos con los reportados previamente. En la actualidad, se está en el proceso de implementación del cálculo numérico, del que se expone el algoritmo que se tiene en ejecución

Effect of the hydrostatic pressure on two-dimensional transport in delta-doped systems

72.20.Fr Low-field transport and mobility; piezoresistance, 73.21.Fg Quantum wells,

Self-consistent calculation of transport properties in Si dÀdoped GaAs quantum wells as a function of the temperature

a b s t r a c t The electronic structure of a delta-doped quantum well of Si in GaAs is studied at different temperatures. The calculation is carried out self-consistently in the framework of the Hartree approximation. The energy levels and the mobility trends are reported for various impurity densities. As a consequence, the temperature dependence of the mobility can be explained by means of the temperature variation of the electronic structure. The calculated ratios between mobilities at 300 and 77 K, at different impurity densities, are in excellent agreement with the experimental data. These results can also be extrapolated to other similar systems like B, GaN, InSb, InAs and GaAs

Scaling behavior in the transmission coefficient for a self-affine multi-barrier system using graphene

By means of a deposited or epitaxial graphene model, we study the transmission coefficient as a function of the incident electron's energy, for a multi-barrier system which is finitely self-affine (i.e., it is self-similar but with different scaling ratios in the x and energy axis) and has mirror symmetry with respect to the center of the structure. The main result is the scaling behavior in the transmission coefficient (which in fact resembles the form of the multi-barrier structure) and the appearance of a scaling relation between curves of different parameter values. This system is finitely self-affine as the number of scaled pieces is finite and the scaling is only made in the energy axis. In order to study the transmission properties of the proposed structure, we consider first different “generations” of its construction, we compute their transmission coefficient curves and then search for some resemblance of the geometric properties of the multi-barrier structure in the form of scaling relations between transmission curves. We find that not only such scaling relations exist, but they are surprisingly simple. In fact they are simple enough to write down a closed algebraic expression that describe them. We thought that this is due to the finite self-affinity property and that it could be used as a basic model to analyze more complicated multi-barrier profiles