Ricerc@Sapienza

At the few-atom-thick limit, transition-metal dichalcogenides (TMDs) exhibit strongly interconnected structural and optoelectronic properties. The possibility to tailor the latter by controlling the former is guaranteed to have a great impact on applied and fundamental research. As we recently discovered, hydrogen (ions) irradiation deeply affects the surface morphology of bulk TMD crystals. H+ ions penetrate the top layer, resulting in the TMD-catalyzed production and progressive accumulation of molecular hydrogen in the first interlayer region. This leads to the blistering of one-monolayer thick domes, which stud the crystal surface and locally turn the dark bulk material into an efficient light emitter. The domes are stable and robust, and host strong, complex strain fields. Lithographic techniques allow to engineer the formation process so that the domes can be produced with well-ordered positions and sizes tunable from the nanometer to the micrometer scale.

The final goal of the "Advanced Nanophotonics based on Hydrogenated Transition-Metal Dichalcogenides (ANaHTraMeDi)" project is the development of a unique platform for the realization of scalable, advanced light emitters, based on single, strain-engineered TMD nanodomes. Such nanodomes will be deterministically integrated in circular Bragg grating (bullseye) cavities, which have shown excellent performances in maximizing the extraction efficiency of the photons emitted by semiconductor nanostructures. Three main device types will be targeted throughout the course of the project: (i) Nanolasers; (ii) Bright single- (and entangled-)photon emitters; (iii) Cavities for the enhancement of the efficiency of nonlinear frequency conversion via Second-Harmonic Generation (SHG). Towards the end of the project we will also aim at achieving full dynamic control of the properties of these devices via strain engineering, by (iv) integrating them with piezoelectric (PZT) actuators.