Electrical characterisation of SrTiO3/Si interfaces

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 degreesC. 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 x 10(11) and 3.5 x 10(12) eV(-1) cm(-1) while the higher temperature deposited samples had a higher D-it ranging between 1 x 10(11) and 1 x 10(13) eV(-1) cm(-2). The above results were also well correlated to X-ray diffraction measurements, Rutherford backscattering spectroscopy, and spectroscopic ellipsometry. (C) 2002 Elsevier Science Ltd. All rights reserved.