Nanomechanik (Meyer)

Our objective is to develop and experimentally validate a new combination of nanopatterning and deterministic doping of phosphorous (P) in silicon (Si) that is required for the manufacturing of quantum devices. Our approach is based on thermal scanning probe lithography (t-SPL), directed self-assembly of block-copolymers (DSA-BCP), monolayer/polymeric-precision doping (MLD/PPD) and rapid thermal annealing (RTA) to create micro and nanopatterns of P-doped areas in Si, down to single atom doping control. The project will first fabricate test patterns (1 um – 20 nm) having variable geometries and dopant concentration inside the Si crystal, e.g. 1D, 2D arrays, with multiple dopant patterns, that allow us to assess the local dopant profile, and to optimize the process by varying systematically fabrication parameters. To ensure single P dopant control, molecule-receiving holes of around 5 nm are needed, which will be achieved using t-SPL and advanced dry etching to create a 20 nm guide pattern, which will subsequently be reduced by DSA of BCP. Inside these holes we will perform P doping by MLD/PPD using molecules of various kinds and sizes with P moieties. The doping patterns will be characterized by advanced surface analysis techniques, e.g. by Kelvin Probe Force Microscopy (KPFM). Results from the KPFM will be used in an iterative way to optimize design and process flow and to achieve single dopant control in a deterministic way. In a second phase, besides continuing to optimize the doping process, we will begin exploring the use of the single doping technology towards concrete quantum devices. We aim to demonstrate that the technology can be incorporated into the standard process flow for donor-based semiconductor devices as for example, single atom point contact transistors, artificial lattices in semiconductors and deterministic doping for semiconducting qubits. Each PhD topic will be aligned to one of the configurations according to status of the advances we can make. The proposed work requires expertise in nanofabrication, self-assembly and ultra-high-resolution surface and device characterization, The project team with members from EPFL, UniBasel and CNM-Barcelona has been assembled to gather the most advanced skill set in the respective project parts present. Our research project will train four new PhD students in a timely topic related to nanomanufacturing and quantum technology.

Layered 2D materials have a wide range of tunable physical properties that offer many potential applications in areas such as photovoltaics, hydrogen evolution catalysis, transistors, DNA detection, nanoelectromechanical systems and tribological applications. Transition metal dichalcogenides (TMDs) are particularly useful in this regard due to their flexible chemistry and stoichiometry. However, the manipulation and assembly of free-standing TMD layers into devices requires a deep understanding and control of their frictional properties at the nanoscale. To address this challenge, the aim of this project is to develop a thorough theoretical and experimental understanding of how to control friction in TMD-based systems at the nanoscale. This will involve identifying the most promising TMD-based heterostructures with targeted functionalities and establishing protocols for designing new tribological materials with tailored frictional properties. The specific scientific objectives of this project are to develop a deep understanding of how to control friction in TMD-based systems on demand, and to identify the best electrical and optical stimuli that can be used as external 'knobs' for users to control friction.

This project aims to develop an advanced optical beam-deflection atomic force microscope (AFM) integrated in a low-temperature cryostat and an ultra-high vacuum system. The system will enable precise study of individual molecules and complex 2D molecular systems. The cryostat, optimized for low helium consumption and long hold times, will support extended experiments, while the vacuum environment will allow in-situ preparation of samples through methods like thermal evaporation and electrospray deposition. The AFM, built at the University of Basel, will include a preamplifier to extend bandwidth and enable faster data acquisition, supporting advanced AFM modes such as multimode AFM. The system will also feature precise positioning of the AFM probe on 2D materials and quantum dot devices, using optical microscopy and large-area scanning. Controlled electrostatic potentials and back-gate voltages will allow for quantum dot confinement and charge density manipulation, facilitating experiments like 2D or 3D force spectroscopy. Molecules will be studied at submolecular resolution, allowing for manipulation and measurement of lateral forces. Examples include investigating molecular knots and nanographene, with a focus on processes like dehydrogenation. Frictional forces on different substrates will also be explored. Finally, high-resolution AFM and Kelvin probe force microscopy (KPFM) will be used to map charge distributions in electron donor-acceptor systems, including those in excited states, offering new insights into molecular interactions and dynamics.