Numerical study of Klein quantum dots in graphene system

TL;DR

This paper develops a numerical method to analyze Klein quantum dots in graphene, explaining experimental observations and exploring how quasi-bound states depend on quantum dot parameters and shape changes.

Contribution

It introduces a new numerical approach to calculate LDOS in KQDs and investigates the effects of shape and intervalley scattering on quasi-bound states.

Findings

Quasi-bound states depend on dot size, energy, and potential.

Intervalley scattering converts quasi-bound states into true bound states.

Shape evolution from circle to semicircle reveals whispering gallery mode mechanisms.

Abstract

Klein quantum dot (KQD) refers to a QD with quasi-bound states and a finite trapping time, which has been observed in experiments focused on graphene recently. In this paper, we develop a numerical method to calculate local density of states (LDOS) of KQD and apply it to monolayer graphene. By investigating the variation of LDOS in a circular quantum dot, we obtain the dependence of the quasi-bound states on the quantum dot parameters (e.g. the electron energy, radius, confined potential, etc). Based on these results, not only can we well explain the experimental phenomena, but also demonstrate how quasi-bound states turn to real bound states when intervalley scattering is taken into considered. We further study the evolution of the LDOS for KQD varying from a circle shape to a semicircle shape, which reveals the mechanism of whispering gallery mode on the quasi-bound states.