Thickness scaling of pyroelectric response in thin ferroelectric Hf1-xZrxO2 films

The scaling of polarization and pyroelectric response across a thickness series (5-20 nm) of Hf0.58Zr0.42O2 films with TaN electrodes was characterized. Reduction in thickness from 20 nm to 5 nm resulted in a decreased remanent polarization from 17 to 2.8 mu C cm(-2). Accompanying the decreased remanent polarization was an increased absolute pyroelectric coefficient, from 30 to 58 mu C m(-2) K-1. The pyroelectric response of the 5 nm film was unstable and decreased logarithmically with time, while that of 10 nm and thicker films was stable over a time scale of >300 h at room temperature. The sign of the pyroelectric response was irreversible with differing polarity of poling bias for the 5 nm thick film, indicating that the enhanced pyroelectric response was of electret origins, whereas the pyroelectric response in thicker films was consistent with a crystallographic origin. Published by AIP Publishing.