Semiconductor Power Consumption ↓ Information Density ↑ ... Development of Next-Generation Devices

Strange GIST Professor Team "Expected to Contribute to Memcapacitor and Memcomputing System Development"

[Figure 1] Schematic diagram of next-generation memory devices utilizing perovskite materials with lattice strain-tuned ferroelectricity and dielectric properties
* Enlarged bottom center illustration: The process of ferroelectricity generation due to the unidirectional displacement of manganese cations (red) caused by lattice strain in the perovskite-structured strontium manganese oxide.

[Asia Economy Reporter Kim Bong-su] Domestic researchers have developed a technology that significantly reduces power consumption and improves information density compared to existing semiconductors. It is expected to contribute to the development of next-generation electronic devices such as memcapacitors and memcomputing systems.

The research team led by Professor Lee Sang-han of the Department of New Materials Engineering at Gwangju Institute of Science and Technology (GIST) announced on the 1st that they succeeded in stepwise controlling the dielectric constant by utilizing lattice (regularly arranged in all directions in a fixed pattern) deformation of perovskite (a material with a molecular structure ABO3 arranged regularly), which is used as a basic material for semiconductors.

The dielectric constant is a measure of how much a material can relatively store charge when an electric field is applied. Although it is an intrinsic property of the material, if this dielectric constant can be controlled in dielectric materials, the storage levels of memory devices can be adjusted, thereby dramatically improving the power consumption and information density of existing semiconductor devices.

It has recently been reported through theoretical calculation papers that some dielectric materials with a perovskite (ABO3) structure can undergo a phase transition from paraelectricity to ferroelectricity depending on lattice deformation. Among them, SrMnO3 (SMO) is a material capable of multiple phase transitions to not only ferroelectricity but also ferromagnetism depending on lattice deformation, and this strong combination of two ferroelectric properties has been spotlighted as a highly promising material for next-generation multi-memory devices. However, in previous experimental implementations of such materials, it was difficult to directly confirm ferroelectricity and dielectric constant due to large leakage currents and structural defects caused by lattice deformation.

To overcome these limitations, the research team devised and applied a selective oxygen annealing method. They experimentally confirmed for the first time in SMO thin films that a phase transition from paraelectricity to ferroelectricity and the stepwise control of the dielectric constant according to lattice strain are possible. By inducing lattice strain in SMO using a pulsed laser deposition method to form crystalline thin films on a strontium tantalum aluminum (LSAT) substrate with a larger lattice constant than SMO, they controlled the lattice strain. Furthermore, by adjusting the thickness of the thin film, they stepwise controlled the lattice strain rate up to 2%.

Moreover, they prepared a SrRuO3 protective layer on the SMO thin film and developed a selective oxygen annealing method by annealing in a high-temperature oxygen atmosphere and then removing the protective layer. This method resolved the large leakage current and structural defects caused by lattice deformation, which were limitations of the SMO thin film, thereby realizing a structurally stable thin film.

Professor Lee said, “Although memcapacitors are attracting attention as next-generation electronic devices, they are still at the material development stage. Our work is significant in providing a starting point for the development of memcapacitors.” He added, “The development of dielectric materials whose properties can be stepwise controlled by lattice strain is expected to lead the development of next-generation semiconductor devices in the future.”

The results of this study were selected as a highlight paper in the international materials science journal ‘NPG Asia Materials’ (IF=10.481) and were published online on the 29th of last month.

This content was produced with the assistance of AI translation services.