Stable ferroelectric properties of Hf_0.5Zr_0.5O₂ thin films within a broad working temperature range

Abstract

The ferroelectric properties of 20 nm Hf0.5Zr0.5O2 (HZO) thin films has been investigated in a wide temperature range from 100 K to 450 K. The remnant polarization of HZO thin films decreases slightly from 24.6 μC cm−2 (100 K) to 17.9 μC cm−2 (450 K), indicating a robust temperature stability. The capacitors also exhibit excellent endurance properties up to 109 cycles at 100 K and 300 K, and their endurance cycles slightly degrades to 108 at an elevated temperature of 450 K. The results show that HZO ferroelectric thin films have great potential for future emerging memory applications in various harsh temperature environments.

Thermal evolution of ferroelectric behavior in epitaxial Hf0.5Zr0.5O2

“…However, recent modeling efforts by Vopsaroiu et al predicts that a ferroelectric's coercive bias should also increase as temperature decreases 28 . For example, Wang et al observed an approximate 50% increase in Zr-doped HfO2 as the temperature decreased from 300 K to 100 K 24 , and based upon a theoretical model 27 , we anticipate an increase of similar magnitude for our own films. Thus, the fixed 5.36 MV/cm field we employ for hysteresis measurements may be insufficient to keep up with evolving coercive bias at decreasing temperature, which prevents the complete switching of the ferroelectric and leads to the decreasing polarization at cryogenic temperatures.…”

“…However, many of these reports investigate endurance at room temperature or higher, where charged defect mobility is high. There are few low-temperature investigations of wake-up and endurance in HfO2, the majority of which involve films grown via ALD [21][22][23][24] . Therefore, considering the noted differences anticipated between ALD-and PLD-grown HfO2 solid solutions, the role of charged defects on the wake-up and fatigue behavior of HfO2-based ferroelectrics may be further elucidated by careful study of epitaxial PLD-grown films.…”

Characterizing Ferroelectric Properties of Hf0.5Zr0.5O2 From Deep-Cryogenic Temperature (4 K) to 400 K

“…13 in the wide-ranging temperatures with small-signal AC frequency from 5 kHz to 100 kHz. Here, it was found that εr experiences monotonic increase with temperature similar to the general observation from other ferroelectric phased materials [14] regardless of the AC frequency.…”

Low-Voltage Permittivity Control of Coplanar Lines Based on Hafnium Oxide Ferroelectrics Grown on Silicon

“…100 K-450 K), hence proving that HfZrO is a temperature-stable ferroelectric. We also carried out extensive experiments on HfZrO-based IDT phase shifters, from which we observed a good stability of the ferroelectric phase of 6-10 nm-thick HfZrO layers up to about 140 • C, thus confirming the results in [27] (these results will be reported elsewhere).…”

“…As regards a possible dependence of the performance of the HfZrO ferroelectric on temperature, a very recent paper [27] clearly demonstrates how the ferroelectric physical properties of HfZrO thin films exhibit very little variations over a broad temperature range (i.e. 100 K-450 K), hence proving that HfZrO is a temperature-stable ferroelectric.…”