Processing of low-dimensional nanomaterials

Driven by Moore’s scaling law and the transition to a sustainable society there is an enormous push to develop nanomaterials for novel device architectures and for device concepts with new functionalities. In order to study new nanomaterials systematically and later implement them into devices, new synthesis processes and techniques need to be investigated and developed, that are reliable, reproducible and scalable with ultimate control at the nanoscale. 

Synthesis and integration of 2-D nanomaterials

In our group we pioneer atomic layer deposition (ALD) for 2D nanomaterials synthesis. ALD is a scalable, low temperature preparation method for thin films which offers precise thickness control down to the sub-monolayer and can therefore be instrumental for the large area synthesis of 2D materials. The current focus of the group is on ALD of 2D transition metal dichalcogenides (2D-TMDs) for (opto)electronics and catalysis.  We use plasma chemistry (plasma-enhanced ALD, PEALD) to control functionalities of the 2D-TMDs, such as morphology, materials phase and stoichiometry. Furthermore, by doping, alloying and by the formation of heterostructures we tune the electrical properties of the 2D TMDs, such as the charge carrier concentration and band gap. 

Integration of 2-D nanomaterials

Another challenge in the 2D nanomaterials field is how to connect these materials efficiently to the outside world. For example, properly functioning contacts and dielectrics need to be fabricated on top of the 2D materials to make functioning nanodevices. Furthermore, patterning of the new nanomaterials also brings in new integration challenges. Patterning of 2D materials conventionally involves lithography using resist films. However, resist residues deteriorate the nanomaterials properties.

In our group we develop new techniques to contact and pattern the 2D nanomaterials. For example, we investigated new techniques based on ALD to form metals and dielectrics on top of graphene, without deteriorating its properties. In addition, to avoid contamination by resist residues as much as possible, we developed a direct patterning approach using a focused ion beam to pattern graphene. Besides we developed new processes for selective area deposition of metals and 2D TMDs for device applications.