Chemical Physics and Dynamics of Surfaces – 2D materials – Mixed dimentionalities Van der Waals heterostructure

Team

• Permanent members: Emmanuel Lhuillier, Yoann Prado, Hervé Cruguel
• PhD student: Charlie Gréboval
• Post-doct: Sang Soo Chee

Beyond graphene and transition metal dichalcogenides (TMDC) assembly into stack of 2D material, a key benefit of 2D atomically thin material is their ability to be functionalized by capping molecule and nanoparticle to form the so, called mixed dimensionalities Van der Waals heterostructure

Here, we explore the coupling of 2D materials such as graphene and TMDC with narrow band-gap nanocrystals to design optically active system in the infrared. While most of part effort for the use of 2D material were relying on the high carrier mobility of the 2D materials, such 2D system offer many additional possibilities such as optical transparency, work function tunability and transparency to field induced back gate.

For example, we have designed a phototransistor combining a superionic gate made of LaF₃, functionalized by graphene, as work function tunable electrodes, and on top of which the channel is made of infrared absorbing HgTe nanocrystals. We have shown that graphene electrodes enable a new mode of operation compared to metallic electrodes. It leads to a pn junction formation which favour the charge dissociation in the infrared absorbing layer.

Figure: Left scheme of a hybrid graphene HgTe heterostructure. Right phase diagram of the hybrid heterostructure revealing the formation of a pn junction.

 

Collaborations