Scandium Aluminum Nitride Studied for Power Electronics Potential
Scientists from the University of Freiburg, the Sustainability Center Freiburg, and the Fraunhofer-Gesellschaft are working together to study a new material structure that might be better suited for future power electronics than even high-performance semiconductor materials such as gallium nitride (GaN).
The recently launched project "Research of Functional Semiconductor Structures for Energy Efficient Power Electronics" (in short "Power Electronics 2020+") will examine the novel semiconductor material scandium aluminum nitride (ScAlN). Prof. Dr. Oliver Ambacher, director of Fraunhofer IAF and professor of power electronics at the Department of Sustainable Systems Engineering (INATECH) of the University of Freiburg, coordinates the supra-regional collaboration. In the above image, researchers at Fraunhofer IAF are characterizing ScAIN material in high-frequency filters. (© Fraunhofer IAF).
Notably, power consumption can only be lowered if electronic systems become more energy- and resource-efficient as they become more powerful.
Silicon electronics has gradually reached the physical limit of its performance capabilities. Especially in terms of required power density and compactness, silicon power electronic components are insufficient to make significant improvements.
The use of gallium nitride (GaN) as a semiconductor in power electronics has already overcome the limitations of silicon technology. GaN performs better in conditions of high voltages, high temperatures, and fast switching frequencies compared to silicon. These performance advantages also result in significantly higher energy efficiency with numerous energy-consuming applications, thereby translating to a considerable reduction in energy consumption.
Fraunhofer IAF has been investigating GaN as a semiconductor material for many years. With the aid of industrial partners, the fruits of these research efforts have already been put to commercial use.
However, the scientists for the project "Power Electronics 2020+" intend to go even further to improve the energy efficiency and durability of the next generation of electronic systems. They plan to use a different and novel material, scandium aluminum nitride (ScAlN).
First Components Based on ScAlN
ScAlN is a piezoelectric semiconductor material with a high dielectric strength that is mostly unexplored worldwide concerning its potential use in microelectronic applications.
Scandium element © By Hi-Res Images of Chemical Elements--http://images-of-elements.com/scandium.php
"The fact that scandium aluminum nitride is especially well suited for power electronic components, due to its physical properties, has already been proven," explains Dr.-Ing. Michael Mikulla, project manager on the part of Fraunhofer IAF.
The goal of the project is to grow lattice-matched ScAlN on a GaN layer and to use the resulting heterostructures to process transistors with high current carrying capacity.
"Functional semiconductor structures based on materials with a large bandgap, such as scandium aluminum nitride and gallium nitride, allow for transistors with very high voltages and currents. These devices reach a higher power density per chip surface as well as higher switching speeds and higher operating temperatures. This is synonymous with lower switching losses, higher energy efficiency and more compact systems," adds Prof. Dr. Oliver Ambacher, director of Fraunhofer IAF. "By combining both materials, GaN and ScAlN, we want to double the maximal possible output power of our devices while at the same time significantly lowering the energy demand," says Mikulla.
Empirical Observations and Crystal Growth Recipes Needed
One of the most significant challenges of the project is crystal growth because neither growth recipes nor empirical values for this material exist yet. The project team needs to develop to achieve reproducible results and produce layer structures that can successfully be used for power electronics.
Collaboration Between Freiburg and Erlangen
The research project will be conducted in close cooperation among the participants including researchers at the University of Freiburg, the Fraunhofer Institute for Applied Solid State Physics IAF, the Sustainability Center Freiburg, and the Fraunhofer Institure for Integrated Systems and Device Technology IISB in Erlangen, which is a member of the High-Performance Center for Electronic Systems in Erlangen. This new collaboration between university research and application-oriented development will serve as a role model for future project cooperation.
"On the one hand, this model facilitates the cooperation with companies through the prompt transfer of results from basic research to application-oriented development. On the other hand, it opens up synergies between two technically complementary Fraunhofer Centers from two different regions and thus improves both their offers for potential customers of the semiconductor industry," reasons Prof. Ambacher.
