Dielectric, energy storage, and loss study of antiferroelectric-like Al-doped HfO2 thin films

Abstract

Antiferroelectric thin films have properties ideal for energy storage due to their lower losses compared to their ferroelectric counterparts as well as their robust endurance properties. We fabricated Al-doped HfO2 antiferroelectric thin films via atomic layer deposition at variable thicknesses (20 nm or 50 nm) with varying dopant concentrations (4 at. % or 8 at. %). 50 nm thick 8 at. % Al-doped HfO2 showed a maximum energy storage density of 63 J/cm3 while maintaining an efficiency of 85%. A study comparing these thin films revealed thicker films allowed for higher operating electric fields and thus higher energy storage densities at operating voltage. The loss tangents of the thin films at operating voltage were under 2% over the range of −4 to 4 MV/cm and at frequencies ranging from 500 Hz to 100 kHz. Reliability studies showed the thin films endure up to 106–107 cycles and the breakdown field of the films yielded Weibull moduli greater than 6 for all our thin films. The Weibull modulus provides a measurement of the consistency of the breakdown strength from sample to sample, with higher moduli indicating a more invariable result. These electrical characteristics along with the thin film's cycling endurance and reliability make antiferroelectric-like Al-doped thin films a promising material for energy storage applications.

Electroceramics for High-Energy Density Capacitors: Current Status and Future Perspectives

“…Apart from these perovskite lead-free relaxor candidates, HfO 2 -based ceramic films have also been explored and demonstrate promising energy storage properties, stabilities/reliabilities, scalability, and integration. W rec ∼ 46 J cm –3 with excellent temperature stability (up to 175 °C) and cyclic fatigue resistant (up to 10 9 time) was reported by Park in a 9.2 nm thick Hf 0.3 Zr 0.7 O 2 film and W rec ∼ 63 J cm –3 with η ∼ 85% were realized in 50 nm thick Al doped HfO 2 ceramic films with excellent temperature and frequency stability …”

“…W rec ∼ 46 J cm −3 with excellent temperature stability (up to 175 °C) and cyclic fatigue resistant (up to 10 9 time) was reported by Park in a 9.2 nm thick Hf 0.3 Zr 0.7 O 2 film 458 and W rec ∼ 63 J cm −3 with η ∼ 85% were realized in 50 nm thick Al doped HfO 2 ceramic films with excellent temperature and frequency stability. 459 3.2.3. Summary of State-of-the-Art in Ceramic MLs and Films.…”

High Energy Storage Performance of All-Inorganic Flexible Antiferroelectric–Insulator Multilayered Thin Films

“…APAPA has the lowest current density compared to PZO, PAP, and APA. Moreover, the higher electric field is mainly concentrated in the AO insulating layer due to lower dielectric constant, which is beneficial to increase E b of the film. − …”

Achieving High Dielectric Constants in Tetragonal Single‐Phase ZrHfO2 Thin Films through the Atomic Layer Deposition Process Using a Mixed Precursor

“…[21][22][23] HfO 2 has also been extensively studied as a representative high-k material for gate dielectric and DRAM capacitor dielectric applications. [24][25][26] Many studies have been performed to increase the k value of HfO 2 , [27][28][29][30][31][32][33][34] for example, through the use of dopants such as carbon, [27] Si, [29] and Al 2 O 3 . [30,31,35] HfO 2 can exist in various crystal structures with different values of k such as the monoclinic (k % 20), orthorhombic (k % 30), cubic, and tetragonal structures (k > 40).…”

“…[24][25][26] Many studies have been performed to increase the k value of HfO 2 , [27][28][29][30][31][32][33][34] for example, through the use of dopants such as carbon, [27] Si, [29] and Al 2 O 3 . [30,31,35] HfO 2 can exist in various crystal structures with different values of k such as the monoclinic (k % 20), orthorhombic (k % 30), cubic, and tetragonal structures (k > 40). In particular, the dielectric constant of tetragonal phase (t-phase) HfO 2 calculated by first-principles calculations in a previous work was approximately 70.…”