Stefan Heun
NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Pisa, Italy
Optimization of few-layer black phosphorus for low-temperature magneto-transport studies
I will review our activities on black phosphorus (bP). We obtain high-quality few-layer bP flakes via mechanical exfoliation in nitrogen atmosphere, liquid phase exfoliation [1], and direct exfoliation in a polymer matrix which also protects the bP flakes at the same time [2].
The bP flakes are structurally characterized by AFM, Raman, and STM. I will present a study of surface modification on exfoliated bP flakes upon subsequent annealing steps, up to 550°C, well above the sublimation temperature. In particular, our attention is focused on the temperature range around 375°C - 400°C, when sublimation starts, and a controlled desorption from the surface occurs with the formation of characteristic well-aligned craters. With atomically-resolved STM images we show that the long axis of the craters is aligned along the [100] (zig-zag) direction of bP [3].
Flakes were also processed into Hall-bar devices. Low-temperature magneto-transport has shown clear evidence for weak localization in these flakes, with a strong in-plane anisotropy due to the crystalline anisotropy of bP [4]. A similar anisotropy was observed for high-field in-plane magnetic fields [5]. Furthermore, the PMMA/bP nanocomposite described above was used to directly fabricate bP devices from it, using the PMMA as an electron beam resist [6].
The author thanks the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 670173) for funding the project PHOSFUN “Phosphorene functionalization: a new platform for advanced multifunctional materials” through an ERC Advanced Grant.
[1] M. Serrano-Ruiz, M. Caporali, A. Ienco, V. Piazza, S. Heun, and M. Peruzzini, Adv. Mater. Interfaces 3 (2016) 1500441.
[2] Elisa Passaglia, Francesca Cicogna, Federica Costantino, Serena Coiai, Stefano Legnaioli, Giulia Lorenzetti, Silvia Borsacchi, Marco Geppi, Francesca Telesio, Stefan Heun, Andrea Ienco, Manuel Serrano Ruiz, and Maurizio Peruzzini, Chem. Mater. 30 (2018) 2036.
[3] Abhishek Kumar, F. Telesio, S. Forti, A. Al-Temimy, C. Coletti, M. Serrano-Ruiz, M. Caporali, M. Peruzzini, F. Beltram, and S. Heun, 2018 2D Mater. https://doi.org/10.1088/2053-1583/aadd20.
[4] N. Hemsworth, V. Tayari, F. Telesio, S. Xiang, S. Roddaro, M. Caporali, A. Ienco, M. Serrano-Ruiz, M. Peruzzini, G. Gervais, T. Szkopek, and S. Heun, Phys. Rev. B 94 (2016) 245404.
[5] F. Telesio, N. Hemsworth, W. Dickerson, M. Petrescu, V. Tayari, Oulin Yu, D. Graf, M. Serrano-Ruiz, M. Caporali, M. Peruzzini, M. Carrega, T. Szkopek, S. Heun, and G. Gervais, arXiv:1808.00858 [cond-mat.mes-hall].
[6] Francesca Telesio, Elisa Passaglia, Francesca Cicogna, Federica Costantino, Manuel Serrano–Ruiz, Maurizio Peruzzini, and Stefan Heun, Nanotechnology 29 (2018) 295601.
