Phyllosilicate Dielectrics for 2D Heterostructures

For many years, the two-dimensional (2D) community has been on the hunt for 2D dielectrics, to support the push toward all-2D devices. The anticipated upsides are the absence of dangling bonds and atomic flatness – which both would improve interfacing between 2D materials, and thus provide better performance and reproducibility if compared to conventional dielectrics. [1]
The most widely used – hexagonal boron nitride (hBN) – has shown some limitations. On one hand, its relative permittivity (εr) is rather low, and quite thick layers are necessary to prevent dielectric breakdown, both of which limit the electric field seen by the semiconductor. Phyllosilicates have drawn some interest as a replacement for hBN, as they are naturally occurring, have substantially higher εr and industrial-scale production would be feasible. [2–6]
The versatility of phyllosilicates such as mica and talc comes through their unique structure, where wide varieties of cations can exist within silicate octahedrons and tetrahedrons, and – as in the case of mica – can even exist between 2D sheets, allowing mechanisms such as charge transfer doping. [1, 7]
In our poster, we show our findings on 2D field-effect transistors created from various combinations of 2D dielectrics and semiconductors. We show the influence of fabrication under inert atmospheres vs. ambient conditions and demonstrate charge transfer doping and its influences on the device characteristics. The role of 2D phyllosilicates is the main focus of the results. To support our findings, Kelvin probe force microscopy is utilized to validate characteristics like Schottky barrier heights and contact resistance. Device characteristics are probed at multiple temperatures between 77K and room temperature.

[1] S. Das, A. Sebastian, E. Pop, C. McClellan, J. Connor, D. Aaron, T. Grasser, T. Knobloch, Y. Illarionov, A. V. Penumatcha, J. Appenzeller, Z. Chen, W. Zhu, I. Asselberghs, L.-J. Li, E. Uygar, N. Bhat, T. D. Antoupoulos, R. Singh, Nat. Electron. 4, 786 (2021).
[2] A. Castellanos-Gomez, M. Wojtaszek, N. Tombros, N. Agrait, B. J. van Wees, G. Rubio-Bollinger, Small 7, 2491 (2011).
[3] Z. Yang, D. Wang, S. Wang, C. Tan, L. Yang, Z. Wang, Adv. Elect. Mater. 9, (2023).
[4] Q. Ji, Y. Zhang, T. Gao, Y. Zhang, D. Ma, M. Liu, Y. Chen, X. Qiao, P.-H. Tan, M. Kan, J. Feng, Q. Sun, Z. Liu, Nano Lett. 8, 3870 (2013).
[5] Y. Y. Illarionov, G. Rzepa, M. Waltl, T. Knobloch, A. Grill, M. M. Furchi, T. Mueller, T. Grasser, Nat. commun. 11, 3385 (2020).
[6] I. D. Barcelos, A. R. Cadore, A. B. Alencar, F. C. B. Maia, E. Mania, R. F. Oliveira, C. C. B. Bufon, Â. Malachias, R. O. Freitas, R. L. Moreira, H. Chacham, J. Appl. Phys. 5, 1912 (2023).
[7] Y. Wang, Y. Zheng, C. Han, W. Chen, Nano Res. 6, 1682 (2021).