Texture in atomic layer deposited Hf_0.5Zr_0.5O₂ ferroelectric thin films

HfO₂-based ferroelectric materials have excellent CMOS compatibility and polarization even in ultrathin films, which is regarded as promising candidate material for memory devices and related electronic devices. However, as the ferroelectric layer thickness scaling down, the consistency of device performance is inevitably affected by the complex polyphase and polycrystalline nature of HfO₂-based ferroelectric thin films. Therefore, obtaining and controlling the texture of HfO₂-based ferroelectric thin films is extremely important for regulating polarization orientation and improving ferroelectric polarization. In this work, 10 nm Hf_0.5Zr_0.5O₂ (HZO) films were prepared by atomic layer deposition (ALD) on Nb-doped SrTiO₃ (NSTO) single crystal substrates. The texture and orientation of HZO films were analyzed through the state-of-the-art spherical aberration corrected transmission electron microscope (Cs-TEM) technique. The domain matching epitaxy between HZO films and NSTO substrate helps eliminate lattice mismatch and residual misfit strain, and ultimately leads to the formation of <112> texture in HZO ferroelectric films. The obtained results represent lattice and interface play an extremely important role in regulating the ferroelectricity of HfO₂-based films, which provides a way to design ultra-thin HfO₂-based materials with excellent ferroelectric polarization by controlling the crystal structure and orientation.