Phase transformations and novel phases in hafnia-based heterostructures

The discovery of ferroelectricity in hafnia has generated great excitement as the promise of a silicon compatible ferroelectric has given new life to research on ferroelectric memories and FETs. Over a decade later, it has become clear that ferroelectricity in hafnia is unlike that of other known ferroelectrics, and many fundamental questions remain unanswered. In a previous experiment on ID28, we have followed the temperature evolution of phases in epitaxial hafnia-zirconia films of different crystallographic orientations and grown under different conditions, observing an irreversible transition from an orthorhombic to monoclinic structure for films grown in oxidising conditions and a possible new, previously unreported phase for films grown in reducing conditions. Here, we propose to investigate the effects of annealing environment and presence of an electrode layer on the phase transformations in hafnia and further investigate the structure and origin of the new phase.