Nanoscale mechanical resonators and oscillators

In this thesis the physics of nanoscale mechanical resonators and oscillators is studied. We discuss two types of resonators. First, a top-down fabricated doubly clamped beam resonator with an integrated piezoelectric actuator is introduced. The second type of resonators are based on layered two-dimensional materials, such as graphene and...

Suspended carbon nanotubes coupled to superconducting circuits

Carbon nanotubes are unique candidates to study quantum mechanical properties of a nanomechanical resonator. However to access this quantum regime, present detectors are not yet sensitive enough. In this thesis we couple a carbon nanotube CNT mechanical resonator to a superconducting circuit which is a root towards such sensitivity.

Diamond Films and Devices: Chemistry, Electronics and Mechanics

Natural diamond is one of the most rare and precious gemstones known to mankind. In addition, it is also known for its exceptional material properties including extreme heat conducting capacity at room temperature, chemical inertness to aqueous environments and excellent electrical insulation that are interesting to both fundamental as well as...

Carbon nanotubes as electromechanical resonators: Single-electron tunneling, nonlinearity, and high-bandwidth readout

A carbon nanotube (CNT) is a remarkable material and can be thought of as a single-atom thick cylinder of carbon atoms capped of with a semisphere. This is called a single-walled CNT and, depending on how the cylinder is rolled up, CNTs are either semiconducting or metallic. A CNT is made into a mechanical resonator by suspending it between two...

Modeling Molecular Junctions: Weak and Strong Coupling Regimes

Electron transport through single molecule connected to the electrodes is an interesting problem from a fundamental point of view, and because of possible applications. From the theoretical point of view, the hope is that understanding the transport phenomena in such systems enables us to explain measurements and develop devices with new...

On Conductance and Interface Effects in Molecular Devices

In this dissertation we discuss ab initio studies of quantum transport through single-molecule devices, using a combination of techniques from quantum chemistry and many-body physics. The molecular transport calculations discussed here are based on the "DFT+NEGF" approach to molecular transport. We first outline the density functional theory ...

Nonlinear beam mechanics

In this Thesis, nonlinear dynamics and nonlinear interactions are studied from a micromechanical point of view. Single and doubly clamped beams are used as model systems where nonlinearity plays an important role. The nonlinearity also gives rise to rich dynamic behavior with phenomena like bifurcations, stochastic switching and amplitude...

Photogeneration Diffusion and Decay of Charge Carriers in Quantum-Dot Solids

Semiconductor nanocrystals (NCs), which can have a variety of sizes, shapes and chemical compositions, will be a large and important family of future advanced materials.This thesis focuses on colloidal semiconductor NC solids, also called quantum-dot (QD) solids, which are promising materials for many applications, such as photo-detectors, field...

Superconducting Quantum Interference based Electromechanical Systems

Mechanical sensors are essential tools for the detection of small forces. This thesis presents the dc SQUID as a detector for the displacement of embedded micromechanical resonators. The device geometry and basic operating principle are described. The SQUID displacement detector reaches an excellent resolution, a factor of 1.5 below the standard...

Electron Transport through Single Magnetic Molecules

Electrical and mechanical effects in single-molecule junctions

In single-molecule junctions, the behavior of a device is determined by the properties of an individual molecule. In this thesis we develop several models to describe both electrical and mechanical effects in such devices, which can be used to design molecules with a specific functionality. We show how the resistance of a molecule varies with...

Molecular functionality in nanoelectronic devices

Charge transport through single molecules in two- and three-terminal mechanical break junctions

During the past decades the downscaling of integrated circuits has been governed by Moore's law, which predicts device dimensions on the order of 10 nm in 2020. Fundamental research in molecular electronics explores the possibility of fabricating such nanoscale devices from single molecules, which offer the prospects of chemical tunability and...

Dynamic Characterization of Silicon Nitride Cantilevers

This thesis describes a series of experiments on dynamical characterization of silicon nitride cantilevers. These devices play an important role in micro-and nanoelectromechanical systems (MEMS and NEMS). They consist of a mechanical part, a sensor or actuator, and an electronic part for readout and control. The core of NEMS and MEMS, the so...

Mechanical systems at the nanoscale

This thesis describes experiments that were done with a wide range of nano(electro)mechanical systems (NEMS). These devices are promising candidates to study mechanics in the quantum regime. The experiments range from AFM measurements on few-layer graphene nanodrums, electrical detection of flexural modes of suspended carbon nanotubes both at...

Quantum transport through single molecules

This thesis describes three-terminal transport measurements through single molecules. The interest in this field stems from the dream that single molecules will form the building blocks for future nanoscale electronic devices. The advantages are their small size -nanometers-, and their synthetic tailorability which allows the molecules to be...

High-frequency nanotube resonators

Dit proefschrift beschrijft een serie experimenten aan nanoelectromechanische systemen (NEMS) met koolstof nanobuis bouwstenen. NEMS zijn mechanische objecten met dimensies van enkele nanometers die interacties aangaan met elektronica. Deze systemen zijn de logische opvolger van micromechanische systemen, en beloven een significante verbetering...

Quantum transport in molecular devices and graphene

As a result of progress in nanotechnology, smaller and smaller electronic circuits can be made. The stage of electrically contacting even a single molecule has now been reached. This stimulates both fundamental and applied research alike. Molecular electronics is hence a booming new field that draws a lot of attention. In this research project...