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Development of Scanning Probe Technology with the Possibility of Noise Measurements

Student: Ivan Churilin

Supervisor: Vadim Khrapai

Faculty: Faculty of Physics

Educational Programme: Physics (Master)

Final Grade: 9

Year of Graduation: 2019

Measurement of the local electronic density of state (DOS) is of great interest when studying the non-equilibrium electronic properties of various nanostructures. Nowadays several theoretical and experimental studies have been published showing the dependence of the DOS on electric current fluctuations in a non-equilibrium state. However, the already well-established methods for measuring shot-noise characteristics where, for example, a semiconductor nanowire is used as a probe have a low spatial resolution, characterized by the area of the ohmic contact of the probe with the obtaining sample. In this thesis it is proposed to develop a device that will measure local fluctuations of electric current in a tunnel contact between a moving probe and a test object, which in the future will allow measurements of the electronic local density of states in various objects and structures. The use of a tunnel contact will significantly increase the spatial resolution of measurements of the sample noise characteristics. The basis for this technique is the fact that current fluctuations in such a configuration depend on the electronic distribution functions in the probe and the object under study. To position the probe relative to the sample under investigation, standard approaches of scanning tunneling microscopy can be used, which will greatly facilitate the task of noise spectroscopy of nanoobjects, and the needle of the tunneling microscope will act as a probe. To perform this task, an STM set up will be analyzed to create its own device with addition of noise scheme for measuring electric current fluctuations in the tunnel contact, methods for fitting the probe to the sample, making needles will be worked out, attempts to scan the surface topography and recording the noise signal will be made.

Full text (added June 7, 2019)

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