Laser-deposited thin hafnium dioxide condensates: Electron-microscopic study

Thin films of hafnium dioxide (HfO$_2$) have been obtained by pulsed laser ablation of hafnium targets in oxygen atmosphere and characterized by transmission electron microscopy and electron diffraction. Conditions ensuring the formation of an amorphous phase, tetragonal and monoclinic modifications of HfO$_2$ have been determined. It is established that the crystalline phase is formed on orienting substrates at lower temperatures than on neutral ones. The phenomenon of epitaxy has been observed for tetragonal modification of HfO$_2$. Annealing in air leads to crystallization of an initially amorphous film with the formation of a monoclinic HfO$_2$ modification.