In-situ structural investigation of non-stoichiometric HfO2-x films using quick-scanning extended X-ray absorption fine structure

• Thin films of HfO2-x were deposited by pulsed laser deposition on glass substrates.
• Different gas atmospheres (O2, Ar, Ar/H2) were used to control the stoichiometry.
• Films deposited under reducing conditions are highly non-stoichiometric.
• As-prepared films are amorphous but crystallize upon heating up to 440 °C.
• Time resolved in-situ X-ray absorption spectroscopy analysis of crystallization.

In this work, we report our results on the synthesis and structural characterization of hafnium oxide thin films prepared by means of pulsed laser deposition. During the deposition, different gas atmospheres (O2, Ar, Ar/H2) were used. Electron probe micro analysis and X-ray photoelectron spectroscopy measurements show that films deposited in Ar or Ar/H2 are oxygen deficient, while films deposited in O2 are stoichiometric. X-ray diffraction data confirm that the as-prepared films are amorphous and form the monoclinic HfO2 phase during annealing. In-situ quick-scanning extended X-ray absorption fine structure measurements carried out at elevated temperatures up to 440 °C showed an increase in the Hf–Hf order. From the time-resolved data the crystallization kinetics are extracted and analyzed using the Avrami model.