  Films of Bi$\rm _2$Sr$\rm _2$CaCu$\rm _2$O$\rm _8$ and Bi$\rm _2$Sr$\rm
_2$CuO$\rm _6$ have been grown using Atomic-Layer-by-Layer Molecular Beam
Epitaxy (ALL-MBE) on lattice-matched substrates. These materials have been
combined with layers of closely-related metastable compounds like Bi$\rm
_2$Sr$\rm _2$Ca$\rm _7$Cu$\rm _8$O$\rm _{20}$ (2278) and rare-earth-doped
compounds like Bi$\rm _2$Sr$\rm _2$Dy$\rm _x$Ca$\rm _{1-x}$Cu$\rm _2$O$\rm _8$
(Dy:2212) to form heterostructures with unique superconducting properties,
including superconductor/insulator multilayers and tunnel junctions.
Transmission electron microscopy (TEM) has been used to study the morphology
and microstructure of these heterostructures. These TEM studies shed light on
the physical properties of the films, and give insight into the growth mode of
highly anisotropic solids like Bi$\rm _2$Sr$\rm _2$CaCu$\rm _2$O$\rm _8$.

Condensed Matter;Superconductivity