Fraunhofer Institute for Silicon TechnologyIn his doctoral thesis, Dr. Simon Fichtner investigated the performance of the piezoelectric thin-film material aluminum scandium nitride (AIScN). In the process, he made the astonishing discovery that AIScN possesses ferroelectric properties, i.e. with the application of an electric field, the electric dipole moment of the material changes - its atomic structure is reversibly switchable and thus capable of storing certain states.
This discovery has the potential to be an innovation in semiconductor development. A decidedly broad field of research is on the horizon, both scientifically and in terms of industrial implementation, which will accompany ISIT for many years to come.
Ferroelectric properties of AlScN open up development potential for semiconductor technology
Fields of application: Piezoelectric microactuators and next generation computing
Specifically, the ISIT scientists are working on two major fields of application for this material: First, AlScN will be the basis for greatly improved piezoelectric microactuators, such as those used in microscanners or micro-loudspeakers. Second, new ferroelectric AlScN devices can make an important contribution to "next generation computing": neuromorphic electronics, non-volatile memories or energy-efficient power transistors will benefit from the outstanding material properties of AlScN.
AlScN based ferroelectric field effect transistors
Over the past year, ISIT scientists have been working on the development of the first AlScN-based ferroelectric field-effect transistors. They pursued the goal of creating the technological prerequisites for increasing the efficiency of power transistors for energy conversion, e-mobility and communication applications, and created the basis of an evaluation of the use of AlScN in memory applications.
Thus, they demonstrated the selective polarization switching of ferroelectric AlScN in silicon-based transistors. This achievement represents an important proof of concept and highlights the potential of the novel material by integrating it into initial devices in addition to advancing materials research.
Customized transistor designs
To this end, various transistor designs were tailored to the needs and strengths of the material system based on process and device simulations. The designs were combined into a unified process flow and fabricated in a first iteration. Comprehensive electrical characterization of these devices is still in progress. However, the initial results already point the way to further improvements in device architecture. In addition to continued integration into silicon-based transistors, a sophisticated roadmap has been established for tight integration of AlScN into the recently added GaN technology platform.
ISIT scientist Dr. Simon Fichtner was awarded the Hugo Geiger Prize for his pioneering development.