Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Poster Session I

DS 17.47: Poster

Tuesday, March 13, 2018, 18:15–20:15, Poster B

Electrical Permittivity Determination of ScAlN Thin Films — •Niclas Feil¹, Nicolas Kurz², Mohammad Fazel Parsapourkolour³, and Oliver Ambacher¹ — ¹Laboratory for Power Electronics, INATECH-Department of Sustainable Systems Engineering, University of Freiburg, Emmy-Noetherstr. 2, 79110 Freiburg, Germany — ²Laboratory for Compound Semiconductor Microsystems, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, Germany — ³Electroceramic Thin Films Group, EPFL, Laussane, Switzerland

Wurtzite scandium-aluminiumnitride (Sc_xAl_1−xN) is a material with outstanding properties. For instance, 400 % increase of the piezoelectric strain constant d₃₃ for Sc_0.43Al_0.57N compared to AlN was reported. This results in a substantially enhanced electromechanical coupling, which is needed for future high frequency piezoacoustic filter devices for the upcoming 5G mobile radio standard. All tensor components are needed for the design of these devices. However, dielectric tensor components are still missing. In this work, the missing є₁₁ component of the dielectric tensor for Sc_xAl_1−xN is determined experimentally for the first time. We developed a method for the determination of the basal permittivity component є₁₁. It is based on the electrical capacitance measurement of interdigital test structures and finite element model optimization. The developed approach was validated with c-axis oriented sapphire substrates and AlN thin films. We observe that the є₁₁/є₃₃ ratio of Sc_0.15Al_0.95N and AlN are different which highlights the change in anisotropic properties.