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| Home > Publications database > Scanning tunneling potentiometry at nanoscale defects in thin films |
| Book/Dissertation / PhD Thesis | FZJ-2018-06257 |
2018
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-361-7
Please use a persistent id in citations: http://hdl.handle.net/2128/20342
Abstract: The continuous miniaturization of electronics has led to smaller and more powerful devices inour everyday life, such as smart phones and tablet computers. This process is substantiated by Moore’s law, which predicts shrinking of electronic devices by a factor of two every two years[1]. While this model described the development over the last decades astonishingly well, it has come clear that it will break down in the near future [2, 3, 4, 5], which results from technical challenges in the fabrication of such small devices. However, even if the fabrication technology would not be the limiting factor, it is clear that at some point a fundamental size-limit for a classical transistor is reached – a single-atom transistor [6]. Generally, transistors consist of areas of differently doped semiconductors, mainly silicon (Si). The doping is the result of atomic defects within this host lattice of Si atoms. The positioning of the dopants in the Si lattice is a random process, such that for ultra-small devices, in the limit where the doping of the Si is determined by only a few doping atoms, small variations in the local dopant configuration can have large effects on the resulting device properties. The same is true for unintentional lattice defects, such as lattice vacancies, interstitial atoms, domain boundaries and step edges on the sample surface. In large devices, the exact number of such defects often is not too critical because the device properties are average over a large volume. In a device consisting of only few atoms however, e.g. an unintended atomic vacancy almost certainly leads to a failure of the device. As a result, the search for alternative concepts for future electronics is flourishing. Recent developments show that spintronics (spin-based electronics) [7] and quantum computing [8] could be a next big step in computer technology. At the forefront of these two topics are three-dimensional topological insulators (3D TIs), which have been first proposed in 2005 [9] by C. L. Kane and E. J. Mele. What makes these materials promising candidates for future electronic devices are their two-dimensional surface states, where the spin of the charge carriers is locked to their momentum. Furthermore, the corresponding dispersion relation has the form of a linear dependence of the energy on the impulse, resulting in the so-called Dirac cone [10]. As a result, new pathways for the realization of spintronics are opened, where the spin polarization of a current can be controlled simply its current direction. Furthermore, it has been shown that TIs in combination with superconductors can lead to the formation of Majorana fermions [11], which are theoretically predicted to be suitable for the preparation of quantum bits [12, 13]. The combination of multiple of such quantum bits into quantum computers has the potential to solve certain problems much faster than any classical computers [14]. However, for these new materials to find their ways into applications, a miniaturization of the corresponding devices is required. Here, again the fabrication of ultra-small devices depends crucially on the behavior of defects in such systems. Due to this ultimate importance, the fundamental properties of defects under current flow have acquired an increasing interest in the research community and also electronics industry [15, 16,17, 18, 19]. ...
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