Ultrafast electron dynamics in twisted graphene by femtosecond photoemission electron microscopy

Twisted multilayer graphene (tMLG) present electronic properties that depend on the relative misalignment and interaction between layers. These interactions affect the band structures and the carrier dynamics upon photonic excitation. These structures are being under scrutiny and recent work high-lighted the strong potential they offer for optoelectronic devices. However, the ultrafast carrier dynamics is still at an early stage, often due to the instrumental limitations. Here, we investigated the carrier dynamics by femtosecond photoemission electron microscopy of chemical vapor deposited (CVD) twisted graphene super lattices presenting different interlayer rotation angles. The photo-generated carrier lifetimes in these selected regions show a longer lifetime compared to monolayer graphene (1 ML). This observation is assigned to the presence of band gap and sub bands in the trilayer graphene and has been supported by DFT calculations.