Epitaxial thin films of BaSrO as gate dielectric

Abstract

Interface trap densities between single crystalline Ba0.7Sr0.3 O and Si (001). Results on p- and n-type substrates. Trap densities between 6 and 9i?1011eV-1cm-2 were found close to midgap.Display Omitted Electronic properties of mixed BaSr oxides.e = 21.8?0.2, interface trap densities 6-9i?1010eV-1cm-2, CET below 1nm.Negligible capacitance-voltage hystereses smaller than 10mV, low leakage currents.Band offsets of 1eV for both conduction and valence bands.Tuning of flatband voltage by insertion of an Al layer at the metal gate. The electronic properties of mixed BaSr oxides were investigated both spectroscopically and by electrical measurements in MOS-diode structures on Si (001). The dielectric properties of crystalline Ba0.7Sr0.3O turned out to be very good with a dielectric constant of ? = 21.8 ? 0.2 , interface trap densities 6-9i?1010eV-1cm-2 near midgap, negligible capacitance-voltage hystereses smaller than 10mV, low leakage currents (below 2mA/cm-2 at 5nm oxide thickness), and band offsets of 1eV for both conduction and valence bands. At the smallest oxide thickness of 5nm a capacitance equivalent thickness (CET) of 0.75nm was achieved. Effective flatband voltages could be tuned by inserting an ultrathin Al layer between metal gate and oxide. Above 400?C the oxide is transformed into a silicate of defined stoichiometry.