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Integration of two-dimensional nanomaterials with functional oxide nanostructures

Periodic Reporting for period 1 - 2DInterFOX (Integration of two-dimensional nanomaterials with functional oxide nanostructures)

Reporting period: 2015-06-01 to 2017-05-31

The objective of the 2DInterFOX project was to study and develop the integration of two-dimensional (2D) nanomaterials with non-2D nanostructures, with a particular focus on non-2D metal oxide nanostructures. This objective is of key technological importance to realize the envisioned potential of 2D materials in nanoelectronics and energy applications, where functional non-2D metal oxides need to seamlessly integrate with 2D materials as e.g. dielectrics, barrier layers, charge transfer dopants or photo-catalysts. Critical to achieving such desired controlled 2D/non-2D integration is however an atomistic understanding of 2D/non-2D interfacing but before the project 2D/non-2D oxide interfacing had only been rudimentary addressed on an atomically resolved level.
In order to clarify key aspects of 2D/non-2D metal oxide interfacing the project employed atomically-resolved, element-specific, aberration-corrected scanning transmission electron microscopy (STEM) techniques to elucidate the structural, chemical and electronic interactions of scalably deposited 2D nanomaterials (graphene, hexagonal boron nitride, MoS2) with device-relevant non 2D metal-oxide nanostructures (e.g. Al2O3, HfO2, ZnO, NbOx). Importantly the project linked realistic ex-situ 2D/non-2D oxide integration processing (evaporation, sputtering, atomic layer deposition) with dedicated ex-situ and in-situ STEM experiments and complementary spectroscopic fingerprinting. Key effects of grain boundaries, layer numbers, adsorbates and contamination in the 2D materials on non-2D nucleation and growth were revealed in the project, thereby increasing the structural control over non-2D nanostructure deposition. Furthermore thickness-dependent phase transitions in the non-2D oxides, correlated with their physical and chemical properties, were elucidated which resulted in deposition of non-standard oxide phases. Finally, during the experimentation also additional atomic scale insights into related 2D/2D integration (graphene/MoS2) and properties of 2D materials and membranes (graphene, hexagonal boron nitride) were gained. The results of the project have primarily been disseminated through publication in international scientific journals as well as through establishing collaborative follow-up work with industrial stakeholders in the field.
The findings of the 2DInterFOX project elucidated various aspects of 2D/non-2D interfacing on an atomically resolved level for the first time. These findings contribute to the development of controlled manufacturing of 2D materials technology, aiding the realization of the multiple promising applications of 2D materials in electronics and energy generation and storage.