Carrier multiplication and optical gain in graphene
Torben Winzer, Ermin Malić · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2014
We present a microscopic study on the pump fluence dependent carrier relaxation dynamics in optically excited graphene. Our investigation focuses on the particular role of efficient Auger processes on the carrier dynamics in different excitation regimes. It turns out that for low fluence excitations, the carrier generating impact excitation prevails over the Auger recombination resulting in a significant multiplication of optically excited carriers. In contrast, for strong excitations, we show the occurrence of a transient population inversion that quickly decays due to the predominant process of Auger recombination.