Dr. Maciej Rogala

University of Lodz, Poland
Maciej Rogala is an experimental physicist working at the University of Lodz (Poland) also previously at the Peter Grünberg Institute (Juelich, Germany). He received a PhD degree in 2012 and specializes in surface physics, particularly in the study of the relationship between nanometer-scale chemical composition and functional properties of oxides. The projects he led include the issues of electrically forced migration of structural defects and its effect on electrical conductivity. Recently he has been working on the surface synthesis of metal oxide with sub-nanometer thicknesses and the resistive switching phenomenon occurring in them as applied to memory and neuromorphic systems.

Talk title: Electrical properties of crystalline MoO3 monolayers
Within the broad group of two-dimensional materials, it is the transition metal oxides that can find commercial applications relatively quickly. This is related to the fact that they allow to take the already proven functionalities of their three-dimensional counterparts from the fields of catalysis, batteries, sensors and optoelectronics to a whole new level in a simple and effective way. This is particularly true for flexible electronics and thin-film systems.

Here we present a monolayer (1L) of MoO3 which is a single layer of the octahedral net with the thickness of 6.9 Å. In contrast to the previously available results, we present highly stable 1L α-MoO3−x which uniformly covers the graphite (HOPG) substrate. We chose such substrate to analyze the growth process on a near perfect, defect- and contamination-free graphene-like layer. This allows for precise scanning probe microscopy characterization performed under the UHV conditions and gives direct information about fundamental physical properties essential for further applications in organic electronic devices such as OLED and OPV and additionally in resistive random-access memories (ReRAM) systems. By a combination of ultraviolet and x-ray photoelectron spectroscopy (UPS and XPS), we investigate the chemical composition of α-MoO3−x /HOPG and the interface-induced defects states. Using scanning tunnelling microscopy and spectroscopy, we investigate the electronic properties of MoO3−x at the nanoscale and prove the ability of nanomanipulation and local electromodifications.

This work was supported by the National Science Centre, Poland, grant 2020/38/E/ST3/00293.

[1] D. A. Kowalczyk et al., 2D Materials, 8, 025005 (2021)
[2] D. A. Kowalczyk et al., ACS Appl. Mater. Interfaces, 14, 44506-44515 (2022)
[3] A. Nadolska et al., Crystals, 13(6), 905 (2023)