Ferroelectric materials are known components that exhibit high electrical polarization. Polarization means the isolation of the negative and positive charges present within a material.
This means that for ferroelectric materials, the “memory” of the material’s previous state, known as hysteresis, can store data in a manner similar to magnetic storage devices such as hard discs.
Hafnium element -based ferroelectric materials show great promise because they appear to be very suitable for silicon computer circuits available today compared to other potential materials.
Previously, it was possible for scientists to obtain ferroelectricity in ultrathin films. Such films can be fragile and difficult to use. Scientists have now reported the first experimental proof of ferroelectricity at room temperature in crystals made of a hafnium-based compound and multiple yttrium doped hafnium dioxide.
Hafnia -based ferroelectric materials seem to have many advantages for computer memory. They provide high stability, lower operating power, speed, and the potential to hold data when power is turned off. But scientists do not fully understand such materials.
This study produced a creative bulk hafnia-based ferroelectric material. The results offer insights into how such materials function and how they are regulated. Also, the findings eliminate the high size limit of materials, thus making such materials easier to use in real-world applications.
The large sample size will help further experiments to better understand the ferroelectric properties of the material. In return, it will help scientists create next-generation non-volatile memory devices.
In 1965, Intel co-founder Gordon Moore explained that the number of transistors on a computer chip would double every two years, a prediction called Moore’s Law. Chip manufacturers have since been able to maintain this rate of miniaturization but are likely to encounter increasing difficulties as a result of the laws of physics.
Hafnia-based ferroelectric materials could help further miniaturize non-volatile memory devices. However, scientists have not been able to produce many forms of the material.
In this study, the new bulk ferroelectric yttrium doped hafnium dioxide developed could allow such an advancement, thus resulting in increased use of hafnia in computer chips and an extension of Moore’s Law.
A research team led by Rutgers University performed neutron powder diffraction measurements on yttrium doped hafnium dioxide with the help of POWGEN, a general-purpose powder diffractometer instrument at the Spallation Neutron Source, a Department of Energy (DOE) user facility at Oak Ridge National Laboratory (ORNL).
POWGEN is known as a high-resolution neutron powder diffractometer that allows the magnetic, crystalline, and local structures of novel polycrystalline materials to be defined. The research team synthesized a crystal of yttrium doped hafnium dioxide with multiple levels of yttrium doping and further ground it into powder for characterization.
POWGEN data show that at some levels of doping, most phases are stable and the oxygen atoms act to allow reverse polarization. Therefore, it confirms the ferroelectricity of the hafnia at room temperature.
Other measurements, such as polarization-electric field hysteresis loops and computational simulations, aid structural analysis, and constitute an important step towards hafnia-based technologies of the future.
The study was financially supported by the Center for Quantum Materials Synthesis funded by the EPiQS initiative of the Gordon and Betty Moore Foundation, Rutgers University, Office of Naval Research, and Department of Defense. Neutron characterization was performed using Spallation Neutron Source, a DOE Office of Science user facility at ORNL.
Xianghan, X., and so on. (2022) Kinetically stabilized ferroelectricity of mostly single-crystalline HfO2: Y. Natural Materials. doi.org/10.1038/s41563-020-00897-x