High permittivity quaternary metal (HfTaTiOx) oxide layer as an alternative high-κ gate dielectric

The authors investigated the optical and electrical properties of the high permittivity (κ) metal oxides, HfTiO and HfTaTiO, using HfO2 as a reference and compared their material properties against their electrical performance. HfTiO has a higher κ value but its band offset is relatively smaller and, therefore, it has greater gate leakage current than HfO2. HfTaTiO has an even higher κ value which compensates for the impact of its small band offset. In addition, HfO2 was found to have more defect states than the other two films, which caused a larger hysteresis in the capacitance-voltage scan and degraded channel mobility.