Program Summary
Scandium (Sc)-doped aluminum nitride (AlN) is a popular material for a number of device applications, including radio frequency (RF) filters, piezoelectric actuators, ultrasonic sensors, microphones, and oscillators. In addition to the advantageous piezoelectric and complementary physical properties of AlN-based materials, the relatively low synthesis temperatures make such materials particularly attractive for integration with electronics platforms when compared with other piezoelectric materials.
Recent work has demonstrated the emergence of ferroelectric switching behavior in highly scandium-doped AlN thin films when the scandium content exceeds ~30%. Such a ferroelectric nitride could enable an enormous number of potential applications in a wide variety of devices, including monolithic integration of ferroelectric non-volatile memory on CMOS, ferroelectric resistive memory, filters, tunable RF components, switchable electro-optical components, non-volatile logic, neuromorphic memory, tunable two-dimensional electron gas (2-DEG) heterostructures, and pyroelectric and thermal energy scavenging devices. Although ferroelectric switching has been demonstrated in a limited scope laboratory setting, further study is needed to more systematically quantify the thickness and doping ranges that exhibit ferroelectric behavior, identify the robustness and reproducibility of the ferroelectric response, and demonstrate ferroelectric nitrides as a technologically useful material.
The Tunable Ferroelectric Nitrides (TUFEN) Microsystems Exploration (μE) topic is focused on determining and demonstrating the range of physical conditions for ferroelectric behavior in doped nitride materials and to characterize the effects of physical dimensions, material composition, and processing conditions. Furthermore, TUFEN seeks to demonstrate device functionality and reliability characterization in concert with the ferroelectric properties of these nitride materials. The μE will explore multiple techniques and approaches to develop a series of ferroelectric property phase diagrams identifying the range of useful properties in concert with initial device demonstrations exploiting the ferroelectric properties that may be used to determine the application space for future development.