Unexpected band-bending of donor-doped PbZr0.52Ti0.48O3 films
N. Barrett, I. Gueye, G.L. Rhun, O. Renault, and E. Defay
Thin Solid Films, vol. 715, art. no. 138423, 2020
We present a study of the correlation between doping induced band shifts in ferroelectric PbZr0.52Ti0.48O3 (PZT) and the electrical characteristics of PZT-based capacitors. Sol-gel grown 220 nm PZT thin films were doped with 1 to 4% La or Nb donors at A and B-sites, respectively. The peak surface capacitance and breakdown field values are obtained for 2% La and Nb. The breakdown field decreases significantly for higher doping suggesting the formation of new conduction paths. Film chemistry is unchanged by La or Nb doping but band shifts are observed. La and Nb doping results in band bending towards the Fermi level, with a maximum shift also at 2% and La doping softens the ferroelectric state as seen from the reduction in the coercive field. The results are consistent with initial compensation of oxygen vacancies by La and Nb doping following thermal activation of defects.