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 HfO2 with/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 orthorhombic Pca21 phase (o phase) more stable. Conversely, the electrons compensated defect ( LaHf +e) makes the nonpolar monoclinic P21/c phase (m phase) more stable. Furthermore, both pure hole doping (without ions substituent) and compressive strain can stabilize the o phase. Our work offers a new perspective on enhancing the ferroelectricity of hafnia.