PhD student position in Scanning Probe Microscopy

Updated: about 2 months ago
Job Type: FullTime
Deadline: 31 Dec 2021

The National Center of Competence in Research (NCCR) SPIN was founded in 2020 at the University of Basel inorder to support research, education and technology transfer in various disciplines, such as quantum physics, materials science, engineering and computer science. Its main objective is to develop reliable, fast, compact, scalable spin qubits in silicon. In the Nanolino Lab we perform various atomic scale experiments, namely controlled self-assembly of materials with atomic precision and we study the unique materials' properties by means of various scanning probe and spectroscopic techniques.

In a project titled Scanning Probe Microscopy for the Characterization of ultra-clean nanowires funded by the NCCR SPIN we will characterize the Si-Ge Nanowires (Si-Ge NW) and Fin FET transistors by pendulum Atomic Force Microscopy (pAFM). Our main objective is to measure energy dissipation and charge noise in Si-Ge NW quantum dots.

In pendulum atomic force microscopy (pAFM) experiment the oscillating tip would probe the charge and spin state transition in Si-Ge NW. The ultra sensitive mechanical oscillators suspended in pendulum geometry (pAFM) detect the charge of the quantum dot due to change of cantilever dynamics. The local potential μ is controlled by the AFM tip voltage and tip-sample separation. The external perturbation caused by an oscillating tip might push a finite quantum system, or a collection of them towards a transition or a level crossing with subsequent relaxation of the system. A level crossing implies a dissipation channel for the external agent provoking the change. For AFM this leads to distance and bias-voltage-dependent dissipation rise of the tip oscillation energy and the modification of the interaction force. The method can quantify the capacitive forces between quantum dot and oscillating cantilever gate as well as amount of dissipated power in the quantum device. The topography of the quantum devices will be reliably measured down to the atomic scale. The AFM tip position on the sample is controlled with nanometer accuracy and the enhanced sensitivity allows to distinguish between electronic, phononic or van der Waals types of dissipation. Measurements can be performed in a wide range of temperatures from liquid helium, liquid nitrogen up to room temperature and in magnetic fields spanning from B=0T to B=7T. The design of the sample holder with implemented external electrodes allows to apply bias voltage to the measured quantum devices.

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