Fabrication of shuttle-junctions for nanomechanical transfer of electrons

Autonomous Implementation of Thermodynamic Cycles at the Nanoscale

There are two paradigms to study nanoscale engines in stochastic and quantum thermodynamics. Autonomous models, which do not rely on any external time dependence, and models that make use of time-dependent control fields, often combined with dividing the control protocol into idealized strokes of a thermodynamic cycle. While the latter paradigm offers theoretical simplifications, its utility in practice has been questioned due to the involved approximations. Here, we bridge the two paradigms by constructing an autonomous model, which implements a thermodynamic cycle in a certain parameter regime. This effect is made possible by self-oscillations, realized in our model by the well-studied electron shuttling mechanism. Based on experimentally realistic values, we find that a thermodynamic cycle analysis for a single-electron working fluid is not justified, but a few-electron working fluid could suffice to justify it. Furthermore, additional open challenges remain to autonomously implement the more studied Carnot and Otto cycles.

Nanopores in 2D MoS2: Defect-Mediated Formation and Density Modulation

Oxidation is a scalable process for introducing nanopores in two-dimensional transitional metal dichalcogenides (TMDs) for membrane applications. The nanopore density is determined by the areal density of their nucleation sites; understanding the nature of the defects and their control would enable tailoring of TMD membranes for targeted applications. In this work, we show that the nanopore distribution is dramatically different in strained and unstrained MoS₂ crystals. We correlate this spatial distribution to the underlying arrangement of dislocations in MoS₂ crystals, in contrast to previously suggested sulfur vacancies. To control the nucleation density of MoS₂ nanopores, we demonstrate that the pore density can be modulated by electron beam exposure prior to the nanopore formation. Raman analysis of electron beam-exposed samples indicates that hydrocarbon adsorption activates defect species other than dislocations, which significantly enhances the nanopore density in MoS₂.

Selected immobilization of individual nanoparticles by spot-exposure electron-beam-induced deposition

The use of spot-exposure electron-beam-induced deposition (EBID) to immobilize targeted nanoparticles on a substrate is demonstrated, and investigated using experiment and simulation. Nanoparticles are secured in place through the build-up of carbonaceous material that forms in the region between a particle and substrate when an energetic electron beam is focused onto the particle and projected through to the substrate. Material build-up directly affects the strength of adhesion to the surface, and can be controlled through electron dosage and beam energy. By selectively immobilizing specific particles within surface agglomerations and removing the excess, we illustrate the potential for spot-exposure EBID as a new technique for nanofabrication.