1st January 2019


Dr. Agnė Žukauskaitė, group manager in the Epitaxy department at Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg, Germany, is responsible for development of piezoelectric materials and shares the latest progress in sputtered AlScN thin films.


Ever since the discovery of enhanced piezoelectric properties of aluminum scandium nitride (Al1-xScxN, later denoted as AlScN) in 2009, the interest in it as a next generation material for broadband RF-filters in 5G communications is still growing. In addition, it is also very attractive for other applications, where piezoelectric transducers and actuators are required, such as bio-sensing, energy harvesting, or acoustics. Here at Fraunhofer IAF, the focus is on bridging the gap between the material science and device design in order to understand how to best implement, or even to open new horizons for this exciting material. Typically, for piezoelectric resonator applications, e.g. RF filters, highly c-axis oriented AlScN layers are preferred. However, growth of AlScN on silicon – the most common substrate in RF-MEMS applications – leads to textured films, i.e., the grains are c-axis oriented out-of-plane, but randomly oriented in-plane. This gives rise to additional acoustic losses in the fabricated devices, decreasing the quality factor Q. If one can go from textured growth to epitaxial growth (clearly defined in-plane epitaxial relationship between the substrate and the film), the device performance can be further improved through superior material quality


This is an extract from an article in LAYERS 4. Edition 2018/2019. To read the full article click here