Observation of different polarity of charges in metal-ferroelectric-semiconductor structures

Capacitors of Au/ferroelectric BaTiO,/p-Si with different constructions of ferroelectric BaTiO, such as single layer amorphous, bilayer of amorphous on polycrystalline, and nanolayer amorphous on a number of stacked layers of polycrystalline on microcrystalline, were fabricated using RF magnetron sputtering. The flat-band voltage, which is a direct indication of the charges in the BaTiO, and at the interface between BaTiO, and Si, was a function of the construction of the BaTiO, layers. Positive charges in the range of 10l2/cm2 were found for single layer amorphous or bilayer amorphous on polycrystalline BaTiO3. However, negative charges in the range of 10 '/cnv were detected for the BaTiO, films with nanolayer structures. The quasistatic capacitance-voltage measurements on different capacitors showed lower interface state density between BaTiO, and Si by using nanolayer structures.