Electrical properties in low temperature range (5K–300K) of Tantalum Oxide dielectric MIM capacitors

Tantalum oxide (Ta 2 O 5 ) is widely used for MIM (Metal-Insulator-Metal) capacitor owing of its high dielectric constant. This work examines current–voltage and capacitance–voltage characteristics in the 5 K–300 K temperature range. Working at low temperature was chosen in order to freeze trapping mechanisms of the MIM capacitor. The curvature of C – V characteristics radically changes from 5 K to 300 K. The capacitance variation under voltage at 50 K and below can be investigated using the Langevin theory. From this model the permanent dipole moment and the number of dipoles have been extracted. From Poole–Frenkel identification curves, activation energy around 0.20 eV and a dielectric constant of 26 were found for positive polarisation. However, conduction mechanisms cannot be reduced to strick Poole–Frenkel modelling.