  We theoretically investigate the frictional drag induced by the Coulomb
interaction between spa- tially separated massless and massive fermions at low
temperatures. As a model system, we use a double-layer structure composed of a
two-dimensional electron gas (2DEG) and a n-doped graphene layer. We analyze
this system numerically and also present analytical formulae for the drag re-
sistivity in the limit of large and small interlayer separation. Both, the
temperature and density dependence are investigated and compared to 2DEG-2DEG
and graphene-graphene double-layer structures. Whereas the density dependence
of the transresistivity for small interlayer separation differs already in the
leading order for each of those three structures, we find the leading order
con- tribution of density dependence in the large interlayer separation limit
to exhibit the same density dependence in each case. In order to distinguish
between the different systems in the large interlayer separation limit, we also
investigate the subleading contribution to the transresistivity. Furthermore,
we study the Coulomb drag in a double-layer structure consisting of n-doped
bilayer and monolayer graphene, which we find to possess the same qualitative
behavior as the 2DEG-graphene system.
