Electrostatic tip effects in scanning probe microscopy of nanostructures
Open Access
- 19 February 2021
- journal article
- research article
- Published by IOP Publishing in Nanotechnology
- Vol. 32 (19), 195710
- https://doi.org/10.1088/1361-6528/abde63
Abstract
Electrical scanning probe microscopies (SPM) use ultrasharp metallic tips to obtain nanometer spatial resolution and are a key tool for characterizing nanoscale semiconducting materials and systems. However, these tips are not passive probes; their high work functions can induce local band bending whose effects depend sensitively on the local geometry and material properties and thus are inherently difficult to quantify. We use sequential finite element simulations to first explore the magnitude and spatial distribution of charge reorganization due to tip-induced band bending (TIBB) for planar and nanostructured geometries. We demonstrate that tip-induced depletion and accumulation of carriers can be significantly modified in confined geometries such as nanowires compared to a bulk planar response. This charge reorganization is due to finite size effects that arise as the nanostructure size approaches the Debye length, with significant implications for a range of SPM techniques. We then use the reorganized charge distribution from our model to describe experimentally measured quantities, using in operando scanning microwave impedance microscopy measurements on axial p-i-n silicon nanowire devices as a specific example. By incorporating TIBB, we reveal that our experimentally observed enhancement (absence) of contrast at the p-i (i-n) junction is explained by the tip-induced accumulation (depletion) of carriers at the interface. Our results demonstrate that the inclusion of TIBB is critical for an accurate interpretation of electrical SPM measurements, and is especially important for weakly screening or low-doped materials, as well as the complex doping patterns and confined geometries commonly encountered in nanoscale systems.Keywords
Funding Information
- National Science Foundation (1848278)
This publication has 48 references indexed in Scilit:
- Visualization of Local Conductance in MoS2/WSe2 Heterostructure TransistorsNano Letters, 2019
- Direct Electrical Probing of Periodic Modulation of Zinc-Dopant Distributions in Planar Gallium Arsenide NanowiresACS Nano, 2017
- Functional Scanning Probe Imaging of Nanostructured Solar Energy MaterialsAccounts of Chemical Research, 2016
- Near-field control and imaging of free charge carrier variations in GaN nanowiresApplied Physics Letters, 2016
- Nano-optical imaging and spectroscopy of order, phases, and domains in complex solidsAdvances in Physics, 2012
- Kelvin probe force microscopy and its applicationSurface Science Reports, 2011
- Principles of Near-Field Microwave MicroscopyPublished by Springer Science and Business Media LLC ,2007
- Electrical Scanning Probe Microscopy: Investigating the Inner Workings of Electronic and Optoelectronic DevicesCritical Reviews in Solid State and Materials Sciences, 2005
- Electrostatic force microscopy: principles and some applications to semiconductorsNanotechnology, 2001
- Surface Studies by Scanning Tunneling MicroscopyPhysical Review Letters, 1982