@phdthesis{,
    author = {Hartwig, Oliver},
    title = {Evaluating the Synthesis and Processing of 2D Materials using Raman Spectroscopy and X-Ray Photoelectron Spectroscopy},
    editor = {},
    booktitle = {},
    series = {},
    journal = {},
    address = {},
    publisher = {},
    edition = {},
    year = {2023},
    isbn = {},
    volume = {},
    number =  {},
    pages = {},
    url = {},
    doi = {},
    keywords = {Nanotechnology; 2D Materials; Raman Spectroscopy; X-Ray photoelectron spectroscopy; Material Synthesis; Characterization; Metrology; PtSe2; MoS2; Graphene; Laser Structuring},
    abstract = {The integration of two-dimensional (2D) materials with the silicon-based semiconductor industry is regarded to be promising to improve the performance of transistors and sensors. In recent years, fruitful advances were demonstrated in the synthesis of 2D materials. However, large-scale, and high-quality production is still challenging for most 2D materials and requires reliable assessment of material quality. In this thesis, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) are primarily used to evaluate the synthesis and processing of 2D materials. Three representative 2D materials PtSe2, MoS2, and graphene were selected as examples to discuss synthesis methods and to demonstrate the characterization techniques. Guidelines were assessed and refined, as well as new guidelines were created for the characterization of 2D materials so that their properties and quality could be determined reliably and within instrument precision. The synthesis and analysis of PtSe2 films were of particular focus. The PtSe2 films synthesized by thermally assisted conversion (TAC) were found to be nanocrystalline with crystallite sizes in the range of 10-50 nm which is in line with previously published observations. In a detailed study of TAC-PtSe2, the correlation of film quality with the structural and electrical properties was investigated. The PtSe2 quality was defined as a combination of crystallinity, chemical composition, crystallite size, and homogeneity of the crystallite size distribution. Raman and X-ray diffraction (XRD) measurements revealed that the average crystallite size could be increased, and the crystallinity improved by using a higher process temperature and increased Se flux. Electrical characterizations showed that primarily the sheet resistance and the piezoresistive GF correlated well with the increased PtSe2 quality determined by Raman, XPS, scanning electron microscopy (SEM), and XRD. Based on the developed guidelines for Raman and XPS characterizations, the structuring of PtSe2, MoS2, and graphene films by femtosecond laser pulses was investigated. The patterning technique was successfully tested by structuring holes and lines, down to 100 nm in diameter or width, into the material films. Additionally, large areas of material films could be removed completely. Using the combination of both methods, the material integrity of non-exposed material areas as close as 100 nm to exposed areas could be confirmed. Finally, PtSe2-silicon Schottky diodes were fabricated by direct growth of PtSe2 on both SiO2 and Si regions of a substrate. Raman and XPS measurements added to the understanding of the PtSe2 synthesis on both substrate regions by confirming successful growth on both regions and by revealing the chemical environment of the produced films.},
    note = {},
    
    school = {Universität der Bundeswehr München},
    
}