  Frank's prediction of the spiral growth mode in 1949 defined a pivotal moment
in the history of crystal growth. In recent decades the topic has received less
attention, and instead we have seen a resurrection of two-dimensional
nucleation theory in the context of growth experiments on defect-free
homoepitaxial thin films. In particular, the key role of interlayer transport
controlled by step edge barriers of the Ehrlich-Schwoebel type in shaping the
morphology of multilayer films has been increasingly recognized. After a brief
review of the classical theory, this paper reports on a recent study of spiral
growth in the presence of step edge barriers. Our key observation is that step
edge barriers lead to unconventionally shaped spiral hillocks that display the
same characteristic ever-steepening height profiles as wedding cakes formed
during growth by two-dimensional nucleation. This prediction was verified
experimentally by inducing screw dislocations through ion bombardment of the
Pt(111) surface, thus creating a homoepitaxial growth system on which spiral
hillocks and wedding cakes coexist.
