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The next‐generation semiconductor memories are essentially required for the advancements in modern electronic devices. Ferroelectric memories by HfO2‐based ferroelectric thin films (FE‐HfO2) have opened promising directions in recent years. Nevertheless, improving the polarization switching speed of FE‐HfO2 remains a critical task. In this study, it is demonstrated that the composition‐graded Hf1‐xZrxO2 (HZO) ferroelectric thin film has more than two times faster polarization switching speed than the conventional composition‐uniform one. Meanwhile, it has excellent ferroelectricity and improved endurance characteristics. It is also discovered that when the HZO thin film has a gradient composition, the polarization‐switching dynamics shifts from the nucleation‐limited‐switching mechanism to the domain‐wall growth mechanism. Moreover, the transition of switching dynamics is responsible for the faster speed and better endurance of the composition‐graded HZO thin film. These findings not only reveal the physical mechanisms of this material system but also provide a new strategy for memory devices having faster speed and higher endurance. [ABSTRACT FROM AUTHOR]

The highly scalable ferroelectric hafnia‐based thin films can be easily integrated into ferroelectric field‐effect transistors (FeFETs) by existing Si technology, which are regarded as one of the promising candidates for fast read/write, energy‐efficient, and high‐density nonvolatile memories. However, device‐to‐device variation in threshold voltage (VTH) caused by non‐uniformity of ferroelectric properties is a serious challenge for implementing hafnia‐based FeFETs in high‐density nonvolatile memories. Here, the substrate‐orientation independent growth of Hf0.5Zr0.5O2 (HZO) thin films is realized with uniform ferroelectricity by using HfO2 seed layers. The HfO2 seed layers are beneficial to improving the ferroelectric polarization of HZO thin films grown on differently oriented Si substrates and reducing the variation in ferroelectric properties. Moreover, device simulation confirms that the proposed scheme contributes to realizing uniform memory properties in 3D vertical HZO‐based FeFETs. This study suggests the possibility to implement hafnia‐based FeFETs into 3D vertical high‐density memory. [ABSTRACT FROM AUTHOR]

CeO 2 -HfO 2 solid solution thin films are fabricated on (100) InAs substrates by chemical solution deposition (CSD) method. The effects of annealing conditions (annealing temperature and atmosphere) on the structural and ferroelectric properties of CeO 2 -HfO 2 solid solution thin films are studied. The results verified that ferroelectric phase of CeO 2 -HfO 2 solid solution thin film could be induced on InAs substrate. In the temperature range studied (550 – 700 ºC), higher annealing temperature profits suppressing nonferroelectric monoclinic phase and promoting ferroelectric orthorhombic phase, and therefore improves ferroelectric polarization. For film annealed at 700 ºC, annealing in N 2 leads to an enhanced ferroelectric polarization (2 P r of 33.9 μC/cm2) compared with annealing in O 2. Importantly, all films can survive 1 × 108 cycles at an applied voltage of 20 V, and do not show significant retention losses, which are benificial for further application. This work highlights the feasibility of integrating CeO 2 -HfO 2 ferroelectric thin films on III-V platform technology. [Display omitted] • Ferroelectric CeO 2 -HfO 2 solid solution thin films are fabricated on InAs substrates by chemical solution deposition method. • Annealing temperature and atmosphere affect the ferroelectric polarizations of the CeO 2 -HfO 2 solid solution thin films. • CeO 2 -HfO 2 ferroelectric thin films on InAs exhibit superior reliability (fatigue and retention). [ABSTRACT FROM AUTHOR]