High energy storage density with HfxZr1-xO2 based 3D capacitors

Electrical energy storage is a stringent manufacturing challenge that requires a low-cost, near-term solution  which can be provided with antiferroelectric capacitors for miniaturized devices and potentially having multiple applications such as in the semiconductor industry (NFC, RFID, IoT...) or in life-sciences.

Hafnium zirconium oxide (Hf1-xZrxO2 or HZO) was selected as material of choice for energy storage (ES), due to the already existing mature CMOS technology  for both Hf and Zr oxides, back-end-of-line (BEOL) compatible character, and its easy integration in 3D nanostructures by conformal atomic layer deposition (ALD). Besides increased power density and ultrafast charge/discharge times as compared to conventional batteries and supercapacitors, it is expected to have increased cycle efficiency and theoretically unlimited lifetime. The challenge is to increase the energy density beyond (100J/cm3) while maintaining high endurance. 
Recent breakthrough [1] shows that the material is promising for high energy storage in the  3D antiferroelectric capacitors, due to a relatively large energy storage density (ESD) in a wide temperature range and a high-power efficiency.
The main research objective is:

1. The stabilization of tetragonal phase  with anti-ferroelectric (AFE) behavior and high dielectric constant (>40) in a multiphasic HZO  for upscaled superlattices
2. Achieve high endurance, implicitly long lifetime beyond 1E+11 cycles in superlattice type of 2D and 3D capacitors [2,3].

Methodology of work will include firstly the stabilization of  AFE tetragonal phase, and secondly its characterization e.g. grain size morphology and chemical analysis by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, etc and electrical evaluation of 2D and 3D capacitors by capacitance-polarization-leakage-voltage measurements and endurance and efficiency evaluation with applied electrical field of  the optimized capacitors.

[1]. S.S. Cheema et al., Nature, 629, 805, 2024.
[2]. M. I. Popovici et al., ACS Appl. Electron. Mater., 4, 4,1823, 2022.
[3]. A.Walke et al, A. M. Walke et al., IEEE Electron Device Letters, 45, 4, 578, 2024.