Tunable emission from two-dimensional semiconductor with platelet optical antennas

Abstract

The remarkable properties of two-dimensional semiconductors allow for abundant research and applications in electronic and optoelectronic area. Monolayer transition metal dichalcogenides (TMDC), such as MoS2 , are direct bandgap semiconductors which hold promises in valley-based optoelectronic applications or light-emitting devices. However, the weak light-matter interaction in this atomically thin slab leads to low absorbance (- 3%) and quantum yield (~ 10-3). Although the quantum yield of monolayer MoS2 is higher compared with its few-layer counterparts, it is still significantly lower than that would be expected for a direct-gap semiconductor. Here, we explore the possibility of tuning the spontaneous emission of monolayer MoS 2 by coupling it with plasmonic platelet antennas, which can both convert freely propagating light into nanoscale and transmit radiation power into free space efficiently. The antennas used are single crystalline and the plasmonic modes are obtained both by near-field imaging and numerical simulation. The tunability of photoluminescence by nearby antenna is analyzed in details. This thesis proposes an economic and promising way to tune the emission of low-quantum-yield emitters, such as MoS2 , while preserving both A and B exciton peaks. This ultrathin structure can facilitate the development of on-chip emitters and valley-based devices.