Towards GHz Detection: Transition Metal Dichalcogenides for Ultrafast Photodetection

Abstract

Transition metal dichalcogenides (TMDCs) are layered materials with extraordinary properties for optoelectronics like high carrier mobilities and large extinction coefficients. They are applicable as mono- or multilayers, in combination with other 2D materials, affordable, and they are compatible with silicon technology. Those properties render them ideal candidates for fast and sensitive next-generation photodetectors. However, the simultaneous optimization of detectivity / responsivity and speed is not possible, as the long carrier lifetimes necessary for a high sensitivity are unfavourable for a fast detection. Recent research has primarily focused on increasing the responsivity with astonishing results, whereas improvements, of the response times have been challenging for pure TMDCs with the exception of more complicated device architectures involving graphene and sophisticated photonics. The objective of this thesis is the development of procedures that enable a GHz response of pure TMDC photodetectors which is still pending to date.