Optical properties of epitaxial SrHf O3 thin films grown on Si

Abstract

The perovskite SrHf O3 can be a potential candidate among the high-permittivity materials for gate oxide replacement in future metal-oxide semiconductor field-effect transistor technology. Thin films of SrHf O3 were grown by molecular beam epitaxy and compared with SrTi O3 films. Their optical properties were investigated using spectroscopic ellipsometry and analyzed with respect to their structural properties characterized by x-ray diffractometry, atomic force microscopy, and transmission electron microscopy. A band gap of Eg =6.1±0.1 eV is measured optically, which renders this material better suited for gate dielectric applications than SrTi O3 with Eg ∼3.4 eV. At similar equivalent oxide thickness, SrHf O3 also exhibits lower gate leakage current than SrTi O3 does. © 2007 American Institute of Physics.