According to research funded by the National Natural Science Foundation of China, Ministry of Science and Technology, ultrahigh-speed, nonvolatile floating-gate memory devices can be achieved without the need to modify commercial device architecture. It can be done by employing 2D van der Waals heterostructures with improved interfacial coupling and atomically sharp interfaces.
In particular, ultrahigh-speed operations with nanosecond write and read times that is limited by instrumentation response, the extremely high extinction ratio of 1010 and a 10-yr retention time have been successfully achieved. This enhanced performance enables new device capabilities such as multi-bit storage, thus opening up applications in the realm of modern nanoelectronics and offering future fabrication guidelines for device scale-up.
The development of high-performance memory devices has played a key role in the innovation of modern electronics. It is critical to developing ultrafast and non-volatile memory devices driven by the explosive growth of massive data storage and the desire for ultrafast data processing. The current bottleneck in the memory field includes operation speed, data retention, endurance and extinction ratio.
In particular, while the scaling of devices continues, silicon-based technology will soon reach a critical limit to meet the increasing demands for memory capacity. One of the key challenges is related to the unavoidable interfacial dangling bonds in ultrathin-body silicon, which causes substantial degradation in device performance. It is thus an urgent need to seek atomically sharp interfaces and integrate them seamlessly into the device architecture.
Among all of the candidates, the emerging two-dimensional (2D) materials and their heterostructures represent ideal atomically flat in-plane surfaces potentially free from surface dangling bonds and are immune to short-channel effects that can allow effective electrostatic control and mechanical flexibility. Indeed, a few examples employing 2D materials for flash memory devices have been recently attempted but with limited device performance.
For example, a very long write time on the order of milliseconds to seconds was observed in the 2D materials based floating-gate memory devices, while alternative semi-floating-gate configurations have shown improved write time (nanoseconds) but extremely short retention time in the range of seconds, making them unsuitable for long-term storage.
Theoretically, an ideal floating-gate memory device based on planar layer materials should allow nanosecond order operational time, but the ultrahigh-speed floating-gate memory has not yet been reported so far.
Floating-gate memory devices based on van der Waals heterostructure with atomically sharp interface have comparable program speed with dynamic randomly accessed memory (DRAM), and simultaneously possessed non-volatile and large storage capacity. This is important for developing future high-performance non-volatile memory devices and provides an alternative route for the development of high-performance electronic devices based on van der Waals heterostructure. The main challenge for further application lies in the epitaxial growth of high-quality and large-scale hBN and two-dimensional atomic crystal materials and their device integration.
Development of Nanoscience and Technology in China
China is consistently committed to the development of nanoscience and technology and has set up research plans keeping up with the international pace of progress. For instance, China established the National Steering Committee for Nanoscience and Technology in 2000 and founded the National Center for Nanoscience and Technology in 2003. The national medium and long-term development program includes nanoscience
By looking at publications of high-quality academic papers, patent applications, key areas of development, international collaborative networks and other aspects, it reveals recent trends of China’s development in nanoscience and technology in comparison to the world. Having also incorporated experts’ interpretations and views, the study applies both qualitative and quantitative analysis.
China has become a strong contributor to nanoscience research in the world and it is a powerhouse of nanotechnology R&D. Some of China’s basic research is leading the world. China’s applied nanoscience research and the industrialization of nanotechnologies have also begun to take shape, with nano-related patent applications leading the world.
These achievements are largely due to China’s strong investment in nanoscience and technology. China’s nanoscience research is also moving from quantitative increase to quality improvement and innovation, with greater emphasis on the applications of nanotechnologies.