Szabo M (2022)
Publication Language: English
Publication Type: Thesis
Publication year: 2022
Since the discovery of graphene in 2004, 2D materials have become a major area of research. Because of a significant research effort, 2D materials like graphene or hexagonal boron nitride (hBN) can be produced in large quantities, and the first tests for integration in wafer-scale semiconductor manufacturing are started. Graphene and hBN do not provide an adequate bandgap to act as semiconductors for most semiconductor devices and are used as a conductor and an isolator. A material with a suitable band gap is black phosphorus (BP), which has promising properties but cannot yet be synthesised on the same scale as graphene and hBN. The challenge of large-scale synthesis of BP is likely to be overcome because great progress has been made in the last years. However, BP provides another challenge with the degradation under ambient conditions. BP oxidises in air, which causes devices to deteriorate over time. Different anti-degradation strategies have been proposed, one of them being the creation of so-called van der Waals heterostructures which are stacks of different 2D materials. In this work, graphene and hBN are transferred onto BP using a large-scale transfer method to create van der Waals hetero structures which are more stable under ambient conditions than pristine BP. Optical microscopy, micro spectroscopy, and atomic force microscopy (AFM) are utilised to characterise the degradation of BP and the van der Waals heterostructures. Because the resolution of the micro spectrometer is not high enough to measure all exfoliated BP flakes, a method to increase the spatial resolution of the micro spectrometer is developed, which makes it possible to increase the resolution of the spectrometer by about 50%. The degradation of unprotected BP flakes can be observed after 70 min. The preparation of graphene BP and BP hBN van der Waals hetero stacks through the so-called trivial transfer method was possible. The transferred graphene layer was able to protect the BP flake for two and a half days, while the hBN layer was only able to protect the BP for 4 h and 48 min. It was attempted to implement a method to track a minimum of the reflection spectrum of the different materials during degradation, which was initially developed to count the number of layers of 2D materials to establish a metric for the degradation speed of BP. Within the scope of this work, this could not be achieved with sufficient validity and therefore further future investigations are needed to determine the extent to which the method can be used for black phosphorus.
APA:
Szabo, M. (2022). Optimierung und Charakterisierung von 2D-Materialien für die Passivierung von schwarzem Phosphor (Master thesis).
MLA:
Szabo, Maximilian. Optimierung und Charakterisierung von 2D-Materialien für die Passivierung von schwarzem Phosphor. Master thesis, 2022.
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