Dresden 2017 – scientific programme

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DS: Fachverband Dünne Schichten

DS 41: Layer Properties: Electrical, Optical, and Mechanical Properties II

DS 41.2: Talk

Thursday, March 23, 2017, 15:15–15:30, CHE 91

ZrO₂ as a high-k dielectric matrix for electrical applications - formation of embedded Ge nanocrystals and a Ta-stabilized orthorhombic phase — •David Lehninger¹, Julia Wünsche¹, Frank Schneider¹, Volker Klemm², Mykhaylo Motylenko², David Rafaja², and Johannes Heitmann¹ — ¹Institut für Angewandte Physik, TU Bergakademie Freiberg, D-09596 Freiberg — ²Institut für Werkstoffwissenschaft, TU Bergakademie Freiberg, D-09596 Freiberg

Germanium nanocrystals (nc) embedded in dielectric matrices are discussed as absorbers for third generation solar cells, as sensitizers for rare earth elements, and as charge trapping layer for nonvolatile memories. Here, the formation of Ge nc in a TaZrO_x matrix was studied. Single GeTaZrO_x and TaZrO_x layers as well as superlattices consisting of alternating GeTaZrO_x- and TaZrO_x-layers with different compositions were sputtered. Crystallization of Ge and TaZrO_x was characterized by transmission electron microscopy, Raman scattering, and X-ray diffraction. It has been found that Ge nc with spherical shape and well-defined size embedded in amorphous TaZrO_x can be formed. The superior properties of single layers of such Ge nc for charge trapping applications were already shown [1]. At elevated annealing temperatures the amorphous TaZrO_x matrix crystallizes in a non-centrosymmetric orthorhombic phase. This makes this material system attractive for fully CMOS compatible ferroelectric applications. [1] D. Lehninger, P. Seidel, M. Geyer, F. Schneider, V. Klemm, D. Rafaja, J. von Borany, J. Heitmann, Appl. Phys. Lett. 106, 023116 (2015)