PhD - Leuven | More than two weeks ago
Since the discovery of graphene in 2004, research interest in 2D materials exploded. The interest in this one atom thick carbon layer stems from its remarkable physical properties and its potential applications (light-based devices, sensors, imagers...). Today, not only graphene but also a dielectric 2D layer (i.e. h-BN) and even semiconducting 2D layers (MX2 materials like MoS2, WS2, WSe2...) are already well under development.
Synthesising these 2D materials is not straightforward, as not only layer (surface) control but also crystallinity of the growth template and the 2D layer is extremely important (i.e. minimizing grain boundaries). In order to obtain application quality, single crystalline 2D layer on wafer scale dimensions, it has been shown that a high growth temperature and a crystalline starting substrate (e.g. sapphire) are difficult to avoid. As a result, a possible integration path for 2D materials in the semiconductor industry will require a 2D material transfer from the growth wafer to a device wafer. This means that it will be crucial to find pathways to overcome the adhesion between the deposited material and the growth substrate. To achieve this goal, one might need to re-engineer the interface after 2D synthesis in order to be able to delaminate the 2D material from the growth surface. This interface re-engineering is extremely challenging, and intercalation is likely required. However, changing the interface using intercalation often remains a very slow process that relies on defects in the layer.
As 2D materials are extremely thin, an intriguing question is if one can alter the bottom interface interaction just by changing the exposed 2D surface. It has been shown already that the wettability (surface energy) of these layers is influenced by the surface on which the material is deposited. In this innovative PhD project, we intend to reverse this concept by engineering the top interface on the 2D material, such that it also influences the bottom interface. Doing this, one could envision a revolutionary, alternative pathway to decrease the adhesion of the 2D material to the growth substrate and enable a controlled 2D transfer. Changing the top environment of a 2D layer in a controlled manner on an atomic level will build extensively on our years of experience using physisorbed or even chemisorbed molecules assembly on 2D surfaces.
The innovative challenge of this project will be to design a functionalization layer on top of the 2D layer in such a way that it strongly alters the interaction of the 2D layer with the growth wafer. As this is an interfacial effect, a subsequent challenge will be to accurately measure the interaction with the bottom surface.
As the multidisciplinary topic is about understanding interfaces, knowledge of several characterization techniques (X-ray techniques, scanning probe techniques, optical techniques (Raman, FTIR),...) is preferred. A genuine interest in physico-chemistry is desired and experience in thin film transfer, 2D material functionalization or surface passivation is considered as a plus. You are a self-motivated and a handy person. The ability to communicate fluently in English is an absolute requirement in our international environment.
Required background: Material science, Chemistry, Physics
Type of work: 60% experimental, 40% analysis/characterization/theory
Supervisor: Stefan De Gendt, ,
Daily advisor: Steven Brems
The reference code for this position is 2020-005. Mention this reference code on your application form.