Ferroelectric Nitride Semiconductors: Physics, Epitaxy, and Emerging Device Applications

The incorporation of group IIIB elements, e.g., Sc and Y, can transform conventional III-nitride semiconductors to be ferroelectric, with significantly enhanced piezoelectric, dielectric, and linear and nonlinear optical properties. As such, ultrawide bandgap ferroelectric nitride semiconductors have garnered significant attention for a wide range of applications in high power, high frequency, and high temperature electronics, optoelectronics, ferroelectrics, acoustoelectric, and quantum photonic devices and systems. To ensure that nitride ferroelectrics can meet the stringent requirements of modern microelectronics and photonics, significant challenges must be addressed. These include large coercive fields, low endurance, poor stability, high leakage current, and high optical loss. In this talk, I will present recent advancements in the epitaxial growth of single-crystalline wurtzite phase ferroelectric nitride heterostructures and nanostructures, including ScAlN and YAlN, utilizing standard epitaxial approaches such as molecular beam epitaxy (MBE). I will begin with a brief overview of the latest research advancements and delve into the physics, challenges and opportunities associated with ferroelectric nitride semiconductors. Their distinctive properties and notable achievements in areas such as physics, material synthesis, operational mechanisms, and related devices will be discussed. Additionally, the obstacles currently faced by nitride ferroelectrics in practical applications will be presented, followed by in-depth discussions of potential solutions, future research directions, and the prospects for further developments in this active field.