Preparation and electrical characterization of amorphous BaO, SrO and Ba0.7Sr0.3O as high-k gate dielectrics



We report on the measurement of band offsets and electrical characterizations of amorphous BaO, SrO and Ba0.7Sr0.3O as alternative gate oxides grown on n-Si(001) at room temperature without further treatments. These materials provide relative dielectric constants close to those expected from bulk values even for ultra-thin films (equivalent oxide thicknesses below 1 nm) and posess very low rechargeable trap densities. Interface defect densities are comparable to other high-k materials for BaO and SrO films, but an order of magnitude lower for Ba0.7Sr0.3O. This demonstrates the importance of both chemical and structural interface effects (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)