PGI Colloquium: Dr. Uwe Schröder, NaMLab, Dresden, Germany

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06 Nov 2020 11:00

Copyright: Dr. Schröder

In the last 10 years, the interest in HfO₂ or ZrO₂ based ferroelectric films for novel semiconductor applications steadily increased. Lead-free CMOS compatible ferroelectric layers even below 10 nm film thickness enable scalable devices like high aspect ratio ferroelectric capacitors (FeCap) and field-effect transistors (FeFET) in 2x nm technology nodes [1][2].

But also further applications like ferroelectric tunnel junctions, neuromorphic, piezo, and pyro electric devices are in discussion [3][4]. Ferroelectric properties are caused by a polar orthorhombic Pca2₁ structure in polycrystalline films with a grain size of typically 20-30 nm. Transmission electron, electrical characterization, and piezo force microscopy studies are revealing single grain/domain nucleation limited switching kinetics with slightly different coercive fields for different single grains [5][6].

Multiple excitation pulses, each of which is insufficient for polarization reversal, induce an accumulative effect, which eventually leads to ferroelectric switching [7]. In addition, such an accumulative switching can be exploited to mimic the integrate-and-fire activity of biological neurons [8], which, together with FeFET-based synapses [9], might allow for building fundamental computing blocks of brain-inspired neural networks.  

[1] T. S. Böscke, J. Müller, D. Bräuhaus, U. Schroeder, U. Böttger, Appl. Phys. Lett., 99, 10, 102903 (2011).

[2] T. S. Böscke, J. Müller, D. Bräuhaus, U. Schroeder, U. Böttger, IEEE Symposium IEDM 2011

[3] S. Fujii, Y. Kamimuta, T. Ino, Y. Nakasaki, R. Takaishi, and M. Saitoh, IEEE Symp. on VLSI Technology (2016) 148.

[4] H. Mulaosmanovic, J. Ocker, S. Müller, U. Schroeder, J. Müller, P. Polakowski, S. Flachowsky, R. Bentum, T. Mikolajick, and S. Slesazeck, ACS Appl. Mater. Interfaces 9, 3792 (2017)

[5] E. Grimley, T. Schenk, T. Mikolajick, U. Schroeder, and J. LeBeau, Adv. Mater. Interfaces 1701258 (2018)

[6] I. Stolichnov, M. Cavalieri, E. Colla, T. Schenk, T. Mittmann, T. Mikolajick, U. Schroeder, and A. Ionescu, ACS Appl. Mater. Interfaces (2018),

[7] H. Mulaosmanovic, T. Mikolajick, and S. Slesazeck, ACS Appl. Mater. Interfaces 10, 23997 (2018)

[8] H. Mulaosmanovic, E. Chicca, M. Bertele, T. Mikolajick, and S. Slesazeck, Nanoscale 10, 21755-21763, (2018).

[9] H. Mulaosmanovic, Symposium on VLSI Technology T176–T177 (2017).