Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: 2D Materials 2: Growth, Structure and Substrate Interaction
O 65.8: Vortrag
Donnerstag, 8. September 2022, 12:15–12:30, S052
Development of strain- and gate-controllable STM sample holder — •Jz-Yuan Juo1, Bong Gyu Shin1, Soon Jung Jung1, and Klaus Kern1,2 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, DE-70569 Stuttgart, Germany — 2Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
An atomic-scale understanding of strain effects on electronic properties is essential for implementing two-dimensional materials into flexible electronics. The scanning tunneling microscopy (STM) is an ideal method to advance this understanding. However, the combination of STM and strain-controllable devices remains challenging due to the high demand for compatibilities with limited STM space, ultrahigh vacuum, and mechanical stability. We have developed an indentation-based sample holder for STM measurements. A gearbox and a piezo stack were used to control the distance between the indentor and 2D materials transferred on the suspended polyimide. The gearbox has a travel range of ∼120 µm and precision of ∼1.4 µm; the piezo stack has a travel range of ∼1.8 µm and precision of <1 nm. The combination of gearbox and piezo stack allowed us to tune the distance between indentor and sample continuously with nanometer precision, characterized by atomic force microscopy. Raman spectroscopy was used to measure strain distribution in monolayer MoS2 at the indented area. The strain controllability is characterized by calculating graphene lattice constant changes in STM atomic-resolution images. Spectroscopic studies confirm the gate tunability by observing Dirac point shifts.