Localized excitations in 2D materials

Localized excitations are relevant for use as single photon emitters (SPEs, for use in quantum communications and computing), as well as a probe for novel physics. In this talk I will present our group’s recent work covering two kinds of localized excitations. For the first time, we create SPE-like peaks in monolayer MoS2, by just using ultralow electron beam accelerating voltages (< 5 kV). We understand the physical origin of these peaks, measure stability, and engineer them using different accelerating voltages. Secondly, we measure localized excitations in near 0-degree twisted MoSe2/WSe2 heterostructure, where we observe several sub-meV peaks in photoluminescence (PL) spectra. Power-dependent PL suggests that certain moiré-interlayer exciton emission peaks start saturating after just 10 nW of excitation power, suggesting deep localization. Remarkably, the time-resolved PL measurements from two closely spaced emissions (separated by < 4 meV) show possible optical cascade nature between these states. We will speculate on the origin of these peaks.

If you would like to meet with Akshay during his visit, please contact Kartik Ayyer.