A comparative study on the structural properties and electrical characteristics of thin HoTi_xO_y, TmTi_xO _y and YbTi_xO_y dielectrics

In this paper, the authors described the structural properties and electrical characteristics of thin HoTi_xO_y, TmTi _xO_y and YbTi_xO_y dielectrics deposited on Si(1 0 0) substrates through reactive co-sputtering. X-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectrometry and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions (temperatures ranging from 600 to 800 °C). The YbTi_xO_y gate dielectric that had been annealed at 800 °C exhibited the thinnest capacitance equivalent thickness and the best electrical characteristics (frequency dispersion, hysteresis voltage and interface-trapped charge in the capacitance-voltage curves). We attribute this behavior to the YbTi _xO_y film forming the well-crystallized Yb ₂TiO₅ structure and improving the surface roughness. This dielectric also shows almost negligible charge trapping under high constant voltage stress.