Memory devices are among the most important electronic components and the main driver for modern mobile systems in terms of information storage and energy-efficient computation and communication. A general requirement for future generation memory devices is size reduction, which can increase the memory density and capacity, a beneficial feature for virtually all applications provided the switching voltage is reasonably low. In recent research, we discovered memory effect in atomically-thin materials sandwiched between metal electrodes, an unexpected discovery in a standard vertical device structure. This represents the thinnest memory devices and can enable advancements in various applications including brain-inspired computing, information storage, and radio-frequency switches. For any use case scenarios, it is important to understand the basic mechanism behind a phenomenon. All the more important for memory devices in order to engineer the atomically-thin devices for a number of performance parameters such as the energy consumption and information retention. This research effort focuses primarily on this basic question of fundamental mechanism(s), which successfully accomplished can advance the field of memory technology, and exemplar applications, specifically radio-frequency switches. The effort will employ a variety of advanced experimental tools to elucidate the underlying physics responsible for this new memory phenomenon. Furthermore, successful achievement of the research objective will pave the path towards commercial development to benefit society in mobile technology.
Atomically-thin materials such as transition metal dichalcogenides (TMDs) have drawn great interest due to its diverse prospects in electronics and optoelectronics. Non-volatile resistance switching has been observed in various solution-processed multi-layer TMDs, including functionalized materials and composites, and TMD-based hybrids, where the resistance can be modulated between a high-resistance state and a low-resistance state, and subsequently retained absent any power supply. Recently, we discovered non-volatile resistance switching behavior in monolayer chemical vapor deposited TMDs in a standard vertical metal-insulator-metal device structure with stable operation under ambient condition at room temperature with low transition voltage, high on/off ratio, low ON resistance and good reliability. This discovery inspires new research on electron and ion transport in two-dimensional semiconductors and insulators for device applications in non-volatile memory, neuromorphic computing, and radio-frequency switches. However, the basic mechanism responsible for the phenomenon is not well understood. As such, this proposal effort focuses in one part to research a variety of experiments using advanced tools to elucidate the underlying physics. The tools to be employed include scanning tunneling microscopy and spectroscopy, transmission electron microscopy, conductive-atomic force microscopy, and temperature dependent transport studies. The other part of the research effort is to design the atomically-thin memory device for high-performance radio-frequency switch applications that will exceed the contemporary metrics for phase-change non-volatile switches. The successfully accomplishment of the research objectives will significantly further the science and applications of TMDs by shedding light on the dynamics and energetics of defects, atoms and ions, and the required conditions that result in reliable memory effect.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
