Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 32: 2D Materials I: Structure and Electronic Properties
O 32.7: Vortrag
Dienstag, 8. März 2016, 12:00–12:15, H24
Spatial conductivity mapping of unprotected and capped black phosphorus using microwave microscopy — Pieter J. de Visser1,2, Rebekah Chua1,3, Joshua O. Island1, Matvey Finkel1,4, Allard J. Katan1, •Holger Thierschmann1, Herre S.J. van der Zant1, and Teun M. Klapwijk1,4 — 1Kavli Insitute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, The Netherlands — 2Department of Quantum Matter Physics, University of Geneva, Switzerland — 3Department of Physics, National University of Singapore, Singapore — 4Physics Department, Moscow State Pedagogical University, Russia
Within the family of 2D materials thin flakes of black Phosphorus (bP) play a special role due to their tuneable direct bandgap and high carrier mobilities. Under ambient conditions, however, degradation changes the electronic properties of bP dramatically within hours [1]. Hence, applying protection measures is essential. We compare different protecting layers by measuring the local conductivity of bP flakes over time with scanning microwave impedance microscopy (sMIM). This novel AFM-based technique [2] probes the local sheet resistance with high spatial resolution and even for buried layers. For a bare bP flake we observe drastic changes in conductivity within 24 h. Coverage with 10 nm of HfOx delays degradation. The bP flake is stable for more than a week. Boron Nitride flakes appear to be less effective as a protection. sMIM reveals that here degradation starts at the edges and evolves over days, indicating a diffusive process. [1] Island J O, et al. 2DMat 2, 011002 (2015). [2] K. Lai, et al. Rev Sci Inst 79, 063703 (2008).