Thickness-dependent ferroelectric properties of HfO2/ZrO2 nanolaminates using atomic layer deposition

Ferroelectric nanolaminates have drawn wide attention due to the process convenience of atomic layer deposition (ALD) method and their superior performance. In this work, HfO2/ZrO2 nanolaminates were prepared by alternately depositing HfO2 and ZrO2 single layer with ALD technology. The crystal structures and electrical properties were comprehensively investigated and analyzed. Compared with HfZrO4 solid solution, HfO2/ZrO2 nanolaminates showed much lower leakage current density and similar ferroelectricity, which was beneficial for the improvement of device life. The highest remnant polarization of 17.7 mu C cm(-2) was achieved in HfO2/ZrO2 nanolaminates with a ratio of 12:12, exhibiting a good endurance of exceeding 5 x 10(9) cycles. The effects of film thickness and laminated structure on the electrical properties and fatigue performance were also discussed. The differences in ferroelectricity and leakage current were originated from the different grain sizes. The small roughness, fine grains and enough crystallization are essential for the better ferroelectric properties. This work provides a comparison between doped films and laminated films and reveals the thickness dependence on the ferroelectric properties of HfO2/ZrO2 nanolaminates.