Charge Effects and Electron Phonon Coupling in Potassium-Doped Graphene.

Herewith, we propose a comprehensive study of the vibrational response of chemical doping of free-standing graphene (Gr). Complementary insights on the increased metallicity have been demonstrated by the emerging plasmon excitation in the upper Dirac cone, observed by inelastic electron scattering and core-level photoemission. The electron migration in the π* upper Dirac band unveils an electron-phonon coupling of contaminant-free K-doped Gr, as evidenced by advanced micro-Raman spectroscopy in ultrahigh vacuum ambient.

X-ray photoelectron spectroscopy of high-throughput mechanically exfoliated van der Waals materials.

X-ray photoelectron spectroscopy (XPS) is a widely used and easy accessible characterisation technique for investigating the chemical composition of materials. However, investigating the composition of van der Waals (vdW) flakes by XPS is challenging due to the typical spot size of XPS setups compared to the dimensions of the flakes, which are usually one thousand times smaller than the spot size. In this work, we demonstrate the feasibility of quantitative elemental analysis of vdW materials by using high-throughput mechanical exfoliations, which favour the coverage of arbitrary substrates with flakes of areas of the order of the cm using minimal quantities of materials (about 10 μg).

Potassium doping of vertically aligned multi-walled carbon nanotubes.

Alkali metal doping of multi-walled carbon nanotubes is of great interest, both fundamentally to explore the effect of dopants on quasi-one-dimensional electrical systems and for energy applications such as alkali metal storage. We present an investigation with complementary photoemission and Raman spectroscopies, fully carried out in an ultra-high vacuum, to unveil the electronic and vibrational response of a forest of highly aligned multi-walled carbon nanotubes by in situ potassium doping. The charge donation by the alkali adatoms induces a plasmon mode, and the density of states undergoes an energy shift consistent with electron donation and band filling of the multi-walled carbon nanotube band structure.

Electrical properties of disordered films of van der Waals semiconductor WS on paper.

One of the primary objectives in contemporary electronics is to develop sensors that are not only scalable and cost-effective but also environmentally sustainable. To achieve this goal, numerous experiments have focused on incorporating nanomaterial-based films, which utilize nanoparticles or van der Waals materials, on paper substrates. In this article, we present a novel fabrication technique for producing dry-abraded van der Waals films on paper, demonstrating outstanding electrical characteristics.

Strain-Enhanced Large-Area Monolayer MoS Photodetectors.

In this study, we show a direct correlation between the applied mechanical strain and an increase in monolayer MoS photoresponsivity. This shows that tensile strain can improve the efficiency of monolayer MoS photodetectors. The observed high photocurrent and extended response time in our devices are indicative that devices are predominantly governed by photogating mechanisms, which become more prominent with applied tensile strain.