Ultrafast hot carrier injection in Au/GaN: the role of band bending and the interface band structure

Plasmon photochemistry can potentially play a significant role in photocatalysis. To realize this potential, it is critical to enhance the plasmon excited hot carrier transfer and collection. However, the lack of atomistic understanding of the carrier transfer across the interface, makes it challenging to design more efficient system. In this work, we apply the non-adiabatic molecular dynamics simulation to study hot carrier dynamics in the system of Au nanocluster on top of GaN surface. By setting up the initial excited hole in Au, the carrier transfer from Au to GaN is found to be on a sub-pico second time scale. After the hole has cooled down to the band edge of GaN, we find some of the charges can return back to Au. By applying different external potentials to mimic the Schottky-barrier band bending, the returning charge can be reduced effectively. Finally, with the understanding of the carrier transfer's pathway, we suggest that a ZnO layer between GaN and Au can effectively block the "cold" carrier from returning back to Au but still allow the hot carrier to transfer.