High-k perovskite dielectric BaHf_1-xTi_xO₃

Interest in high-k materials continues as the semiconductor devices shrink in size and in its operating voltage. BaTiO₃ is a well-known perovskite ferroelectric material and BaHfO₃ is a perovskite high-k dielectric material with a dielectric value of 38. In this study, we fabricated capacitors with an atomically-mixed BaHf_1-xTi_xO₃ (BHT, with x varying from 0 to 0.8) layer as the dielectric insulator with a perovskite semiconductor La-doped BaSnO₃ (BLSO) layer as the electrode. All the layers were epitaxially grown on SrTiO₃ substrates by pulsed laser deposition. X-Ray diffraction was used to investigate the structural properties, from which we confirmed the epitaxial growth of all the layers and obtained their respective lattice constants. The electrical properties of the capacitors, such as the capacitance and breakdown field, were measured. As the x value increased, the relative permittivity value increased and the dielectric breakdown field decreased. When the x value of BHT was 0.4, the relative permittivity and breakdown field values were 61.7 and 5.85 MV/cm, respectively, yielding the maximum 2D charge density 2x10¹⁴ cm^-2. We will report on the field effect transistor performances with BHT as the gate dielectric and BLSO as the channel layer.