Ricerc@Sapienza

Many of the goals of the present project are linked to the exploitation of the effects of H irradiation on technologically relevant materials. 1) Semicondutor materials and nanostructures. A part of the activities will regard dilute nitrides (such as, GaAsN and InGaAsN), which are III-V semiconductors interesting for photovoltaics and telecommunications thanks to their near-IR band gap. Some of the participants showed that H incorporation leads to the formation of stable N-H complexes resulting in a fully tunable variation of their energy gap via N passivation. This provides a route to the on-chip fabrication of single photon emitters made of site-controlled GaAsN quantum dots (QDs) obtained either by H irradiation of lithographically prepatterned samples. In addition, this activity will be of great interest to a recently funded ERC Starting Grant by Dr. De Luca (researcher at the Physiscs Department), who will employ the ion source for creating quantum dots in nanowires an innovative nanostructural architecturing. The source will be employed also to turn the semimetallic character of graphene into a semiconductor character by the opening of a gap in graphene. As demonstrated recently by some of the proposers, this will be accomplished by means of a H irradiation that causes a change of the the graphene C sp2 bonds in sp3 bonds and in turn a distortion of the bonds. In turn, this enablesg the formation of band gap energy in the material. The concerned activity will explore the most efficient conditions for achieving large amounts of adsorbed H in nanoprous graphene. Carbon nanotubes produced in the Physics Department will be also subjected to H irradiation to investigate possible modifications in the electronic stucture as to employ them in advanced high-energy particle detectors. 2) Hydrogen storage for green energy applications. This part of the activities will focus on hydrides for energy storage systems. H2 storage in the solid state using hydrides is deemed more efficient and convenient. In this activity, it will be investigated the storage capability of Mg-based hydrides and novel porous hybrid crystals after different irradiations with both hydrogen and deuterium to investigate their performances in terms of optimal uptake of the gas. 3) Hydrogen-induced mechanical deformation of 2D materials. The 2D materials here considered are transition metal dichalcogenides (TMDs) and hexagonal boron nitride (hBN). The proposer's group discovered recently that exposure of bulk TMD and hBN flakes to H results in the formation of atomically thin H-filled micro- and nanobubbles on the sample surface [Ted19,Blu20]. In particular, the local exfoliation of the uppermost layer of the bulk TMD associated with the formation of the bubbles results in efficient light emission. Furthermore, the strain engendered in the bubbles can be exploited for mechnical resonators and the fabrication of spatially-controlled single photon emitters. Other activities will concern the study of the effects of low-enery proton irradiation on the mirrors employed in the Virgo interferometer. It will be pursued an investigation of the vibrational properties of the ion-irradited mirrors using in-situ micro-Raman measurements. This will allow us to assess any improvement in the mirror characteristics at the sub-micron length scale.