  Due to Klein tunneling in graphene only quasi-bound states are realized in
graphene quantum dots by electrostatic gating. Particles in the quasi-bound
states are trapped inside the dot for a finite time and they keep bouncing back
and forth till they find their way out. Here we study the effect of an induced
gap on the scattering problem of Dirac electrons on a circular
electrostatically confined quantum dot. Introducing an energy gap inside the
quantum dot enables us to distinguish three scattering regimes instead of two
in the case of gapless graphene quantum dot. We will focus on these regimes and
analyze the scattering efficiency as a function of the electron energy, the dot
radius and the energy gap. Moreover, we will discuss how the system parameters
can affect the scattering resonances inside the dot.
