Electrical characterisation of SrTiO3/Si interfaces

Deposition of SrTiO ₃ (STO) thin films by ultra-high vacuum rf magnetron sputtering was performed in order to produce high-quality STO/p-Si (1 0 0) interfaces and STO insulator layers with high dielectric constants. The deposition temperatures were in the range from room temperature to 550 °C. Capacitance–voltage ( C– V) and conductance–frequency measurements showed that the dielectric constant of the films ranges from 55 to 120. C– V measurements on Al/STO/p-Si structures clearly revealed the creation of metal–insulator–semiconductor diodes. The interface state densities ( D _it) at the STO/p-Si interfaces were obtained from admittance spectroscopy measurements. The samples deposited at lower temperatures revealed values of D _it between 2×10 ¹¹ and 3.5×10 ¹² eV ⁻¹ cm ⁻² while the higher temperature deposited samples had a higher D _it ranging between 1×10 ¹¹ and 1×10 ¹³ eV ⁻¹ cm ⁻² . The above results were also well correlated to X-ray diffraction measurements, Rutherford backscattering spectroscopy, and spectroscopic ellipsometry.