Espalhamento de pacotes de ondas em canais quânticos formados por semicondutores porosos

Abstract

Disorder in experimentally two-dimensional (2D) heterostructured semiconductor materials is inevitable, which can originate from charged impurities, vacancies or atomic substitution. Numerous exciting phenomena arise in disordered quantum materials, such as the metal-insulator transition which can be explained by the Anderson localization effect. For transport properties, a 2D system with potential disorder can exhibit diffusion-ballistic and location-dislocation transitions by decreasing (holding fixed) the size of the system for a fixed (increasing) disorder. The presence of porosities in semiconductor materials, called porous materials, can be used to propose new devices for applications, such as waveguides. For the study of the electronic states for a porous quantum system (well), made of InAlAs/InGaAs, it is necessary to numerically solve the time-independent Schrödinger equation in the approximation of the effective mass with the finite difference technique. In the context of electronic transport properties and porous materials, an adequate theoretical and didactic description is based on the propagation of wave packets. Thus, we investigate the dynamics of the wave packet traveling through a porous semiconductor channel with the defects being simulated by a disordered scattering region produced by obstruction potentials. The theoretical framework is based on the split-operator technique to solve the time-dependent Schrödinger equation within the effective mass approximation. In the simulation, the semiconductor channel made by InGaAs with a width of 100 Å is considered, grown on InAlAs substrate, and the porous ones are taken with circular symmetry and different densities. The results for the probability, reflection and current transmission coefficients are analyzed for different: initial values of kinetic energy of the Gaussian wave packet, disordered pore densities, pore randomness. We show an intersub-band transition strongly dependent on the configuration of the disordered scattering region.