Hybrid graphene tunneling photoconductor with interface engineering towards fast photoresponse and high responsivity

Abstract

Optoelectronics: tunneling photodetectors break the trade-off between speed and responsivity Graphene-based photodetectors with an embedded MoS2 tunnel layer show remarkable responsivities, whilst still retaining fast response times. A team led by Jian-Bin Xu at the Chinese University of Hong Kong tackled the trade-off between speed and responsivity by intercalating two-dimensional MoS2 into a graphene photodetector. This results in the formation of a hybrid tunneling photoconductor, where silicon plays the role of optically active layer, whereas MoS2 serves as tunneling layer. The insertion of ultra-thin MoS2 enables fast transfer of the photo-excited carriers in silicon towards graphene, whilst also passivating surface states. This approach effectively bypasses the speed limitations caused by the long lifetime of trapped interfacial carriers, resulting in a remarkable 17 ns response time and a high, broadband responsivity up to 3 × 104 A/W.