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HL: Fachverband Halbleiterphysik
HL 30: Poster I
HL 30.29: Poster
Dienstag, 17. März 2020, 13:30–15:45, P3
Structure and dielectric function tensor of (Al,Sc)N thin films — •Sascha Kürth, Rüdiger Schmidt-Grund, Stefan Krischok, and Katja Tonisch — Institut für Physik, Technische Universität Ilmenau, Weimarer Straße 32, 98693 Ilmenau, Germany
We present the dielectric function tensor of (Al,Sc)N thin films for the full composition range and derive material properties such as band-gap energies and refractive index dispersion. The thin films have been grown on silicon with conductive interlayers such as platinum and titanium nitride and on sapphire by reactive sputter deposition. Both, the structural as well as optical properties vary with Sc content and with the actualy used substrate. While excitonic enhancement is observed mainly for pristine aluminium nitride, the transition between the hexagonal and cubic crystal structure of ScAlN is observed by the transition between optic uniaxiality and isotropy. For increasing Sc content, we further observe a redshift of the optical absorption edge as well as an increase of the refractive index.
(Al,Sc)N is a very promising material system for piezoelectric applications as the piezoelectric coefficient gains values as big as d33= 28 pm/V [1]. But only recently films of sufficient quality have been achieved, thus a comprehensive understanding of optical and electronic properties is still missing.
[1] T. Yanagitani, M. Suzuki, Appl. Phys. Lett. 105, 122907 (2014).