Growth of highly oriented monoclinic HfO$_{2}$ thin films after Co and Fe doping by pulsed laser deposition

Above room-temperature ferromagnetism in undoped and Co doped high-k dielectric HfO$_{2 }$thin films opens up the possibility for using spin functionality in various new electronic devices. In the present work, we report on the growth of high quality epitaxial HfO$_{2}$ thin films stabilized in monoclinic phase after 5{\%} Co or Fe doping at 700-800$^{o }$C in an oxygen partial pressure of 10$^{-4}$ torr on (001) yttria stabilized zirconia and (001) Si substrates by pulsed laser deposition. On the one hand, pure HfO$_{2}$ film did not grow epitaxally under various deposition conditions. On the other hand, the formation of single crystalline phase after Co or Fe doping was confirmed by X-ray analysis. Ion channeling analysis in Co and Fe doped films showed 8-24{\%} minimum yield indicating highly oriented film growth, whereas, a very poor minimum yield was observed in the undoped case. Angular scans showed the HfO$_{2}$ to grow in a monoclinic phase with a 9.1 degree tilt with respect to the substrate. High resolution transmission electron microscopy showed very sharp interface while Electron energy loss spectroscopy revealed that Co is in 2+ state indicating the substitution of Co in ionic form into the HfO$_{2 }$lattice.