Propriedades eletrônicas em junções P-N em monocamada de grafeno

Abstract

In the constant search for new technologies to circumvent the limitations found in modern nanoelectronics whose devices are based on conventional semiconductors, mostly silicon, the scientific community has been attracted to studies in two-dimensional materials since the experimental isolation of graphene in 2004. Graphene, a single sheet of graphite, exhibits several atypical physical properties allowing in many cases the observation of phenomena predicted by quantum field theories for relativistic particles, such as the Klein tunneling, where electrons with normal incidence through pn and pnp junctions present a perfect transmission, and the Zitterbegung effect, where quantum observables such as position and momentum oscillate as a function of time. The exotic properties of graphene originate from the fact that such material has a linear dispersion relation in the vicinity of the Fermi level, and consequently, low-energy electrons behave like massless Dirac particles obeying an equation analogous to the equation of Dirac. Within the context of graphene and in addition to optoelectronic devices, it is natural to study junctions formed by excess or lack of electrons, that is, pn junctions that can be generated or by doping or application of potentials, as such junctions are a key part of semiconductor devices, such as the diode. Thus, in this work, the behavior of electrons and holes in a graphene quantum dot was studied when subjected to potential applications in order to produce a p-n junction. It was investigated the spacial distribution of the confined states and how charge carriers interact with the effects of the edge and the interface of the junction and with each other when applying a magnetic field perpendicular to the quantum dot surface. Three different orientations for the junction were analyzed in a rectangular graphene quamtum dot with well-defined edges of the types armchair and zigzag.