Spontaneous nano-clustering of ZrO2 in atomic layer deposited LayZr1-yOx thin films: Part 1 – Material characterization

During atomic layer deposition (ALD) of uniform LayZr1-yOx thin films, spontaneous segregation of ZrO2 nanocrystals takes place that are embedded in an amorphous La2O3 matrix. This occurs if the Zr content in the LayZr1-yOx film is above 30% i.e. if the pulse ratio between the lanthanum precursor and the zirconium precursor is larger than six. We study this clustering phenomena using High resolution Transmission electron Microscopy (HRTEM) and X-ray diffraction (XRD) techniques. XRD analyses show that the ZrO2 nanocrystals are in the tetragonal phase, which is the most stable phase of this material. Conclusions: In conclusion, this Technical Note reports the effects of mixing precursor pulses of lanthanum and zirconium in ALD, which results in the spontaneous formation of nanocrystalline ZrO 2 crystals in an amorphous La 2 O 3 matrix, instead of a homogeneous La y Zr 1-y O x film. We find that below 30% Zr content the spontaneous crystallization is very unlikely, though short-range order is still feasible. ZrO 2 nucleated in the film are in tetragonal phase, which is the most stable phase of ZrO 2