Figure Captions

Sorry that these figures aren't on-line, but there's no way to store a high-resolution photo in a reasonably-sized file. I'll be happy to send anyone a preprint by mail to anyone who requests one.

Figure 1: A high-resolution cross-sectional TEM image showing overgrowth of a 2212 superconductor film on a SrTiO₃ substrate (001) surface. The view is along the (100) axis of the SrTiO₃ substrate. Registry between planes in the substrate and overlayer is nearly perfect, resulting in a coherent interface. The BiO planes are continuous throughout the image, even directly above rough areas on the SrTiO₃ surface.

Figure 2: A high-resolution cross-sectional TEM image of a 2201/2212 superlattice. The view is along the (001) axis of the SrTiO₃ substrate. The alternation of the 15.4 Å period of 2212 and the 12.3 Å period of 2201 is readily identifiable. Also shown are image simulations of 2212 and 2201 which were calculated using the known lattice constants of the materials. Parameters for the simulations are focus = -450, thickness = 200Å.

Figure 3: Hypothetical crystal structure of the Bi-2278. The c-axis lattice constant is 71.2 Å, so the thickness of a single layer should be 35.6 Å. The in-plane lattice constants are assumed to be the same as in 2212. The view is along the (001) axis. Shown for comparison is the well-known crystal structure of the 2212 phase.

Figure 4: High-resolution cross-sectional image of a 2278 barrier layer sandwiched between two thick films of 2212. The view is along the (001) axis of the SrTiO₃ substrate.

Figure 5: High-resolution cross-sectional image of a twinned section of a 2212 film. The layers on the right-hand side of the image have the b-axis normal to the plane of the figure and show incommensurate modulation. Layers on the left-hand side have the a-axis normal to the plane of the figure.

Figure 6: Stacking defects in a 2212 film grown on SrTiO₃ substrate. View is along the (001) axis of the SrTiO₃ substrate. The antiphase boundary is indicated by a black arrow.

Figure 7: Low-resolution micrograph of a BiSrCaCuO film with three barriers each consisting of a single molecular layer of 2278, separated by thicker layers of 2212. This image demonstrates the long lateral coherence length which is typically observed in BiSrCaCuO-based heterostructures grown by ALL-MBE.