Voltage Programmable Pyroelectric Sensors With ZrO₂-Based Antiferroelectrics

The physics operating at the nanometer scale in antiferroelectric devices has provided a pathway for new voltage programmable, passively operated pyroelectric sensors. Zr
$_{{1}-{x}}$
HfxO2 thin films of 8 and 6 nm thickness are incorporated into workfunction-engineered capacitors to provide nonvolatile switching of pyroelectric and nonpyroelectric states. The different operating principles of the voltage control of the pyroelectric response between ferroelectrics and antiferroelectric pyroelectric switches are demonstrated. Simple ± 2.5-V voltage pulses can turn the pyroelectric effect on and off in the workfunction-engineered ZrO2-based thin-film antiferroelectric capacitors. Zero-field pyroelectric coefficients with magnitudes of up to
$108\,\,\mu \text{C}\,\,\text{m}^{-{2}}\,\,\text{K}^{-{1}}$
were measured in the pyroelectric ON-state. Hf-doping lowered the endurance of the nonpolar OFF-state with switching cycles, where degradation was observed to begin at
$10^{{4}}-10^{{6}}$
cycles. The loss of the nonpolar state and the convergence of the ON- and OFF-state pyroelectric coefficients after
$10^{{10}}$
cycles was attributable to an irreversible phase transition to the ferroelectric phase, in agreement with the “wake-up” phenomenon widely observed in HfO2 and ZrO2-based films. Undoped ZrO2 exhibited the best cycling endurance with an OFF-state pyroelectric coefficient magnitude of
$10.3\,\,\mu \text{C}\,\,\text{m}^{-{2}}\,\,\text{K}^{-{1}}$
after
$2 \times 10^{{10}}$
cycles, demonstrating the potential for long lifetime pyroelectric devices. The robust demonstration of the operating principles and performance of these programmable antiferroelectric pyroelectric sensors establishes a new design framework for high-speed and reconfigurable pyroelectric systems.