Advances in laser-free topographic control of the scanning thermal microscope

Lee, James M.K.Y. (2024) Advances in laser-free topographic control of the scanning thermal microscope. PhD thesis, University of Glasgow.

Abstract

Scanning thermal microscopes typically employ the ‘beam bounce’ optical lever method to measure nano-scale deflection in their probes. This is a robust and simple approach for many experiments and has been the primary form of deflection measurement of atomic force microscope cantilevers since the 1980’s. However, illumination can have a significant impact on the behaviour of the probe or sample being studied. Examples include materials that have light-sensitive behaviour (e.g. semiconductors), and laser illumination creating an additional heat flux to the probe. The measurement of microstructures deflecting without employing optical methods has been addressed in commercial micro-electro-mechanical systems (MEMS) sensors, that typically employ strain gauges or capacitive approaches to measure the deflection of their mechanical sensing elements. This thesis looks to investigate the integration of self-deflection sensing into the SThM system for the purposes of topographic control. The inclusion of strain sensors, based on the electron tunnelling effect, onto the cantilever was explored using high-accuracy overlay alignment techniques developed in this work through novel iterations of the Penrose marker. This work also explores the already available SThM thermal signal as a means of “thermal feedback” topographic control of the microscope. Through the development of custom electronics and control techniques, combined thermal and topographic scans of topographic, thin film, and active semiconductor samples have been presented in air, under liquid, and in vacuum environments without cantilever illumination from an optical lever laser, showing vertical topographic resolutions greater than 5nm.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Funder's Name: Engineering and Physical Sciences Research Council (EPSRC)
• Supervisor's Name: Dobson, Dr. Phil and Weaver, Professor Jonathan
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84746
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Dec 2024 16:24
• Last Modified: 12 Dec 2024 11:05
• Thesis DOI: 10.5525/gla.thesis.84746
• URI: https://theses.gla.ac.uk/id/eprint/84746