Identification number: LZP-2025/1-0601
Type: Latvian Council of Science Fundamental and Applied Research project
Duration: 01.09.2025. - 31.08.2028.
Project Leader: Dr. phys. Andrei Kholkin, Institute of Solid State Physics University of Latvia (ISSP UL)
Total funding: 299 973 EUR
Project summary:
The discovery of scalable, Si-compatible, and robust ferroelectricity in doped-Hafnium oxide based nanostructures (thin films so far) has been instrumental in the resurgence of ferroelectric memories and FEFETs in microelectronics. This ferroelectricity is unconventional, and by now it is accepted that oxygen vacancies, electrochemistry, and vacancy-stabilized metastable states play a crucial role in stabilizing it. But the exact reasons by which polarization is created in these materials and switches, are still under investigation worldwide.
Most of the salient aspects in conventional ferroelectrics have been understood in bulk first, and the lessons and design principles learned from bulk studies accelerated the design of functionality and devices in thin films. However, in the case of ferroelectric hafnia, so far, ferroelectricity has not been stabilized in bulk, making it difficult to systematically assess the arising questions. Through this proposal, first, we attempt to change this paradigm and stabilize ferroelectricity in bulk via microwave hydrothermal synthesis by using 3+ cation doped hafnia ceramics. Metastable phases are known to be stabilized by microwave synthesis methods, oxygen vacancies are induced by substituting cations of different sizes and charge states (3+) than hafnia. Thus, from a materials design perspective, the bulk synthesis has all the ingredients required to stabilize unconventional ferroelectric phases in hafnia. On these materials, we will perform rigorous structure-property characterization via available techniques such as high-resolution electron microscopy and EELS to understand the structural and chemical dynamics during polarization switching.