The effect of thickness and temperature on dielectric properties of lutetium oxide thin films grown by electron-beam deposition on quartz

Lutetium oxide films (Lu2O3) of different thicknesses (d = 47–546 nm) were prepared by physical vapor deposition method with an electron-beam gun. The dielectric properties of Lu2O3 films were examined in metal/insulator/metal-type structures. The influence of the temperature (T = 300–500 K) and the frequency (f = 0.1 mHz–3 MHz) on dielectric properties was examined. At room temperature, the structures exhibited high capacitance density of 0.2–2 fF/μm2. Thick, as-deposited, films were characterized by the dielectric permittivity of 12.9, whereas for films thermally annealed the permittivity was 11.1. For films thinner than 120 nm the permittivity decreased down to κ = 9.6. This effect was caused by thin near-electrode layers at both metal/insulator boundaries. Effective capacitance of these two near-electrode regions was 20.7 fF/μm2, as determined from the capacitance–temperature characteristics.

► We examine the Al–Lu2O3–Al structures. ► These capacitors exhibit high capacitance density and dielectric constant of 12.9. ► Films thinner than 120 nm exhibit thickness dependence of dielectric constant. ► Near-electrode layers are formed at both metal–insulator boundaries. ► These layers affect the dielectric properties at low frequency and high temperature.