Publications

Thickness scaling of pyroelectric response in thin ferroelectric Hf _1-xZr _xO₂ films

Smith, Sean S.; Henry, Michael D.; Brumbach, Michael T.; Rodriguez, Mark A.; Ihlefeld, Jon F.

In this study, the scaling of polarization and pyroelectric response across a thickness series (5–20 nm) of Hf_0.58Zr_0.42O₂ 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 μC cm^-2. Accompanying the decreased remanent polarization was an increased absolute pyroelectric coefficient, from 30 to 58 μC 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. Finally, 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.