Electrical characterisation of SrTiO3/Si interfaces

Abstract

Deposition of SrTiO3 (STO) thin films by ultra-high vacuum rf magnetron sputtering was performed in order to produce high-quality STO/p-Si (100) 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 (Dit) at the STO/p-Si interfaces were obtained from admittance spectroscopy measurements. The samples deposited at lower temperatures revealed values of Dit between 2×1011 and 3.5×1012 eV−1cm−2 while the higher temperature deposited samples had a higher Dit ranging between 1×1011 and 1×1013 eV−1cm−2. The above results were also well correlated to X-ray diffraction measurements, Rutherford backscattering spectroscopy, and spectroscopic ellipsometry.