Monolayer MoS2 and MoS2/Quantum Dot hybrids: novel optoelectronic materials

Abstract

In this thesis we first briefly explore the barrier properties of monolayer graphene. We investigate how films of graphene can be used to decouple underlying metallic (Cu, Ni) substrate from the environment to passivate corrosion. In the remaining part of the thesis we explore the effects of the environment on electrical transport and optical properties of monolayer MoS2. In particular, we investigate the role of the underlying substrate, metallic contacts to MoS2 and phonons on intrinsic transport properties (e.g. carrier mobility) of MoS2. We then investigate the interplay between gate-induced charge carriers and excitons in MoS2 and discover the tunability of MoS2 optical properties (absorption/photoluminescence). Such strong electron-exciton interaction in MoS2 also opens up the possibility to study interesting quasi particles like trions and biexcitons in a 2D system. Finally, we thoroughly investigate Förster resonant energy transfer (FRET), a uniquely efficient long-range optical process, between quantum dots and monolayer MoS2. We discover that modest gate-induced variation in the excitonic absorption of MoS2 leads to large (~500%) changes in the FRET rate and allows modulation of quantum dot photoluminescence intensity.