Aysha A. Riaz

A correlation between depth-resolved defect chemistry and operando electrochemical response is established for compositionally graded gadolinia-doped ceria (GDC)/yttria-stabilized zirconia (YSZ) thin film electrodes.

An investigation of the electronic structure of K ₂ SiF ₆ based on GW theory and photoelectron spectroscopy reveals that Auger–Meitner decay of K 3p holes is energetically forbidden in this material.

In perovskite oxide heterostructures, bulk functional properties coexist with emergent physical phenomena at epitaxial interfaces. Notably, charge transfer at the interface between two insulating oxide layers can lead to the formation of a 2D electron gas (2DEG) with possible applications in, e.g., high‐electron‐mobility transistors and ferroelectric field‐effect transistors. So far, the realization of oxide 2DEGs is, however, largely limited to the interface between the single‐crystal substrate and epitaxial film, preventing their deliberate placement inside a larger device architecture. Additionally, the substrate‐limited quality of perovskite oxide interfaces hampers room‐temperature (RT) 2DEG performance due to notoriously low electron mobility. In this work, the controlled creation of an interfacial 2DEG at the epitaxial interface between perovskite oxides BaSnO ₃ and LaInO ₃ is demonstrated with enhanced RT electron mobility values up to 119 cm ² Vs ⁻¹ —the highest RT value reported so far for a perovskite oxide 2DEG. Using a combination of state‐of‐the‐art deposition modes during oxide molecular beam epitaxy, this approach opens up another degree of freedom in optimization and in situ control of the interface between two epitaxial oxide layers away from the substrate interface. Thus this approach is expected to apply to the general class of perovskite oxide 2DEG systems and to enable their improved compatibility with novel device concepts and integration across materials platforms.

In₂O₃ is the parent oxide semiconductor for many transparent conducting oxides owing to its comparatively wide band gap and reasonable conductivity. The ability to fabricate thin films of In₂O₃ utilising simple and cheap solution-processed methods has made it appealing for applications in displays and solar cells. However, to optimise and improve the optoelectronic properties of these films and enable scalability, understanding the fundamentals behind the solution chemistry is essential and often overlooked. Current research highlights the use of stabilisers to maintain the solution over time and facilitate the formation of strong M–O–M bonds but rarely delves into the underlying chemistry or discusses the effect of varying the stabiliser concentration. This paper explores the impact on the quality of In₂O₃ thin films when altering the concentration of monoethanolamine used as a stabiliser. UV-visible and infrared spectroscopy are employed to track changes to the solution over time to explore the role of the stabiliser. In parallel, thin films prepared from solutions at different time points were characterised using X-ray photoelectron spectroscopy, atomic force microscopy, and ellipsometry. Through this approach, changes in the solution can be directly correlated to thin-film characteristics, crucial for their use in electronic applications.