  This work investigates the electronic properties of the energy spectrum of a
hybrid system composed of (i) a circular quantum dot of monolayer graphene
surrounded by an infinite sheet of AA-stacked bilayer graphene and (ii) a
circular quantum dot of AA-stacked graphene bilayer surrounded by infinite
monolayer graphene. We establish analytical findings for the related energy
levels and wave functions using the continuum model and the zigzag boundary
conditions at the graphene monolayer-bilayer interface. We investigate the
effects of perpendicular magnetic, dot radius, and electrical fields on the two
types of hybrid system quantum dots. We compare our results to previously
published work and explore the potential uses of such a hybrid system quantum
dot.
