Structure and stability of La- and hole-doped hafnia with/without epitaxial strain

The significance of hafnia in the semiconductor industry has been amplified following the unearthing of its ferroelectric properties. We investigated the structure and electrical properties of La- and hole-doped HfO₂with/without epitaxial strain by first-principles calculations. It is found that the charge compensated defect with oxygen vacancy (LaHfVO) and uncompensated defect (LaHf), compared to the undoped case, make the ferroelectric orthorhombicPca21phase (ophase) more stable. Conversely, the electrons compensated defect (LaHf+e) makes the nonpolar monoclinicP21/cphase (mphase) more stable. Furthermore, both pure hole doping (without ions substituent) and compressive strain can stabilize theophase. Our work offers a new perspective on enhancing the ferroelectricity of hafnia.