Influence of postdeposition annealing on structural properties and electrical characteristics of thin Tm ₂ O ₃ and Tm ₂ Ti ₂ O ₇ dielectrics

We describe the structural properties and electrical characteristics of thin thulium oxide (Tm ₂ O ₃ ) and thulium titanium oxide (Tm ₂ Ti ₂ O ₇ ) as gate dielectrics deposited on silicon substrates through reactive sputtering. The structural and morphological features of these films were explored by X-ray diffraction, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and atomic force microscopy, measurements. It is found that the Tm ₂ Ti ₂ O ₇ film annealed at 800 °C exhibited a thinner capacitance equivalent thickness of 19.8 Å, a lower interface trap density of 8.37 × 10 ¹¹ eV ^-1 cm ^-2 , and a smaller hysteresis voltage of ∼4 mV than the other conditions. We attribute this behavior to the Ti incorporated into the Tm ₂ O ₃ film improving the interfacial layer and the surface roughness. This film also shows negligible degrees of charge trapping at high electric field stress.