The voltage-dependent manipulation of few-layer graphene with a scanning tunneling microscopy tip

Abstract

Strain and deformation alter the electronic properties of graphene, offering the possibility to control its transport behavior. The tip of a scanning tunneling microscope is an ideal tool to mechanically perturb the system locally while simultaneously measuring the electronic response. Here we stretch few-and multi-layer graphene membranes supported on SiO2 substrates and suspended over voids. An automated approach-retraction method stably traces the graphene deflection hysteresis curve hundreds of times across four samples, measuring the voltage-dependent stretching, from which we extract the hysteresis width. Using a force-balance model, we are able to reproduce the voltage-dependent hysteretic graphene extension behavior. We directly observe a voltage-dependent interplay where electrostatic forces dominate at high voltage and van der Waals forces at low voltage. The relative contribution of each force is dependent on the graphene and tunneling resistance, giving rise to different observed voltage-dependent behavior between samples. Understanding the voltage dependence of these forces impacts scanning probe measurement of 2D materials and informs oscillating graphene device design where similar forces act from the side walls of cavities, leading towards strain engineering of layered 2D systems.

An improved dynamic Prandtl–Ishlinskii hysteresis model and a PID-type adaptive sliding mode controller for piezoelectric micro-motion platform

“…machining and measurement, and micro-bio medical engineering, the demands for precision in ultra-precision positioning technology have been increasing. For instance, the intricate circuit design and fabrication within micro-robots [1]; ultra-precision machining of micro-array structures on singlepoint diamond turning machines [2]; surface topography measurement or micro-manipulation of individual atoms using precision measurement instruments like AFM [3], STM [4], and SPM [5]; and surgical operations on cells under a microscope using optical tweezers [6,7]. Traditional motor-driven actuators, with their complex structures, multiple transmission links, and issues like friction and deformation, cannot meet the high precision requirements for micro-nano driving.…”

Thomas–Fermi theory of out-of-plane charge screening in graphene

“…The problem of characterizing the charged impurity screening by the graphene sheet has been studied, using a number of theoretical approaches [8–14] (this list is not intended to be exhaustive). Note that a similar question arises in the studies of graphene-based devices in the proximity of a conducting electrode, or when a scanning tunnelling microscope tip approaches a graphene sheet [15]. In particular, in this situation, the electric charge the layer is exposed to may exceed the elementary charge e by many orders of magnitude.…”