Switching Dynamics of HfO₂–ZrO₂ Nanolaminates With Different Laminate Thicknesses

In this work, the switching dynamics of HfO <tex-math notation="LaTeX">₂</tex-math> –ZrO <tex-math notation="LaTeX">₂</tex-math> nanolaminate ferroelectric (FE) films with different laminate thicknesses are investigated. Metal/FE layer/metal capacitors with HfO <tex-math notation="LaTeX">₂</tex-math> –ZrO <tex-math notation="LaTeX">₂</tex-math> alternate cycle ratios n ( n <tex-math notation="LaTeX">$=$</tex-math> 1, 8, 15, 25, and 37) are fabricated, and the hysteresis loop and switching dynamics of these devices are measured. All nanolaminate samples exhibit ferroelectricity and show reduced spontaneous polarization compared with the controlled Hf <tex-math notation="LaTeX">0.5</tex-math> Zr <tex-math notation="LaTeX">0.5</tex-math> O <tex-math notation="LaTeX">₂</tex-math> (HZO) sample. The differences in switching dynamics are analyzed by the inhomogeneous field mechanism (IFM). It is found that: 1) the switching becomes slower with laminate thickness increases. The HZO sample shows the fastest switching due to fewer pinned domains. 2) Decreasing the laminates within a certain range to form a laminate structure is beneficial for higher remanent polarization, better endurance, and fast switching speed. The improvement in the HfO <tex-math notation="LaTeX">₂</tex-math> –ZrO <tex-math notation="LaTeX">₂</tex-math> alternate laminate device with 8 and 15 cycle ratios could be attributed to higher orthorhombic fraction, grain boundary interruption, and enhanced nucleation. This work provides guidelines for designing devices with HfO <tex-math notation="LaTeX">₂</tex-math> –ZrO <tex-math notation="LaTeX">₂</tex-math> nanolaminate layers.