Multidimensional scanning probe microscopy applications for optoelectronic charge carrier characterizations of metal oxides

Abstract

Characterization and optimization of charge carriers (e.g., electrons, holes, ions, vacancies, etc.) feature in renewable energy sample systems (particularly metal oxides, i.e., MOs) heavily rely on the right physical scale (i.e., submicrosecond time resolution and nanometer scale distance resolution) measurement techniques and correct methodologies. Advanced scanning probe microscopy (SPM) techniques like time-resolved atomic force microscopy (tr-AFM) and its unique/customized variants are utilized to reveal migration tendencies and characteristics of these carriers. In this work, customized AFM setups and measurement techniques are used to quantitatively reveal electronic properties of metal oxides, like contact potential differences, charge carrier dynamics, etc., to optimize the lifetime of MO-based systems. Particularly, the charge carrier migration properties of metal oxides (e.g., TiO2) for their photocatalytic tendencies through defect engineering activities and surface characterizations play a significant role in these systems. Sample system properties are investigated from multiple dimensions, where temperature, location, and time are the main variables. Photoinduced surface oxygen vacancies introduced with ultraviolet surface irradiation played a key role in the alteration of the charge carrier dynamics in MO systems. Additionally, external stimuli (e.g., ultraviolet irradiation, voltage pulses, etc.), surface agents (e.g., methanol) and different interfaces (e.g., Au-TiO2) were explored to extend the investigation of key charge carrier dynamics features like mobilities, time constants, activation energies, migration barriers, distance and/or history dependencies.

Date	17 Jun 2025
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Omur Dagdeviren (Supervisor)