Chemical and structural properties of atomic layer deposited La₂O₃ films capped with a thin Al₂O₃ layer

X-ray diffraction and infrared spectroscopy measurements are conducted in order to assess the crystallographic structure and chemical purity of lanthanum oxide (La₂O₃) films grown by atomic layer deposition (ALD) on Si substrates. In situ capping with thin aluminum oxide (Al₂O₃) layer is proved to be beneficial in preventing the formation of lanthanum hydroxide phases. The effect of two process parameters, namely, La₂O₃ film growth temperature (260–500 °C range) and postdeposition annealing temperature (600–1100 °C range), on the chemical and structural evolutions of Al₂O₃/La₂O₃/Si stacks is discussed. This study enables the identification of the optimum ALD growth recipe yielding the highest hexagonal La₂O₃ phase content, which might be suitable for integration into innovative metal oxide semiconductor devices.