Structural and electrical properties of crystalline (1−x)Ta2O5–xAl2O3 thin films fabricated by metalorganic solution deposition technique

Abstract

Polycrystalline (1−x)Ta2O5–xAl2O3 thin films were fabricated by metalorganic solution deposition technique on Pt-coated Si substrate at a temperature of 750 °C. Thin films with 0.9Ta2O5–0.1Al2O3 composition exhibited improved dielectric and insulating properties compared to Ta2O5 thin films. The measured small signal dielectric constant and dissipation factor at 100 kHz were 42.8 and 0.005, respectively. The temperature coefficient of capacitance was 20 ppm/°C in the measured temperature range of 25–125 °C. The leakage current density was lower than 6×10−8 A/cm2 up to an applied electric field of 1 MV/cm. A charge storage density of 18.9 fC/μm2 was obtained at an applied electric field of 0.5 MV/cm. The high dielectric constant, low dielectric loss, low leakage current density, and good temperature and bias stability suggest (1−x)Ta2O5–xAl2O3 thin films to be a suitable dielectric layer in integrated electronic devices in place of conventional dielectrics such as SiO2 or Si3N4.