@phdthesis{,
    author = {Prechtl, Maximilian Andreas},
    title = {Synthesis, Characterization and Applications of Layered 2D PtSe2},
    editor = {},
    booktitle = {},
    series = {},
    journal = {},
    address = {},
    publisher = {},
    edition = {},
    year = {2023},
    isbn = {},
    volume = {},
    number =  {},
    pages = {},
    url = {},
    doi = {},
    keywords = {2D, PtSe2, MOCVD, Synthesis, TAC, Optics, Sensing, ULISSES, Nanotechnology, Materials Science},
    abstract = {The ever-increasing demand for better performance sensors and devices with smaller footprints continues to push research to new limits. Recently discovered two dimensional (2D) materials are drawing significant interest due to their outstanding properties despite their atomic thickness. One material within this class is platinum diselenide (PtSe2), which consists of a platinum plane one atom thick, sandwiched in between two selenium layers. PtSe2 offers the outstanding electronic attribute that it can behave as either a semi-metal or a semi-conductor depending on its layer number. It has additionally been shown to be a promising candidate for chemical sensing applications, furthermore, exposure to ambient conditions does not drastically harm its performance. With its layer dependent band gap in the infrared (IR) regime, it is of major interest for optical sensing applications. However, one key requirement , and a challenge, for future integration of PtSe2 into real devices is controllable, large-scale, and reproducible synthesis methods. In this thesis, two different synthesis approaches for PtSe2, namely conformal and selective thermal assisted conversion (TAC) and metal organic chemical vapor deposition (MOCVD), are developed. In the first part of this work PtSe2 synthesis by combining platinum atomic layer deposition (ALD) and TAC is described. Pt-ALD is chosen as metal source to enable conformal and selective deposition. By tuning of the amount of deposited Pt-ALD cycles before TAC, PtSe2 layers of different thicknesses are synthesized. Raman spectroscopy and atomic force microscopy (AFM) measurements are conducted to characterize the centimeter scale films. Conformality is investigated by scanning and transmission electron microscopy (SEM and TEM) measurements. Good electrical performance is demonstrated by electrical characterization, furthermore, the fabrication of a 3D gas sensing device with reduced size and high sensitivity towards gaseous ammonia is described. An approach for area selective deposition is developed by exploiting the different chemical surfaces of hydrofluoric acid etched silicon and unetched alumina. Selectivity of the process is established by spatially resolved X-ray photoelectron spectroscopy (XPS) measurements. The fabrication of a fully integrated IR photodetector is described which is achieved by conformally and selectively depositing a PtSe2 pad to sheathe a silicon waveguide. The functionality of the device is confirmed by a variety of optical measurements. In the second part of this work, the synthesis of PtSe2 by MOCVD is discussed. Different approaches to tune the layer quality of the deposited 2D material are investigated. After defining the optimum process parameters, the deposition of different thickness PtSe2 films by tuning, and calibrating, the exposure times of precursor sources is investigated for a variety of substrates. The material is characterized by Raman and XPS measurements, AFM measurements are used to determine the growth rates on different substrates. Scanning tunneling measurements are used to investigate the grown material on the atomic scale. A dry etching process for patterning MOCVD grown PtSe2 is developed, electrical measurements confirm the viability of the process as well as the good electrical performance of the material. Using SEM and X-ray diffraction measurements the crystallographic difference in between TAC and MOCVD grown PtSe2 is determined. This thesis offers guidance for PtSe2 synthesis, presenting two inherently contrasting approaches for PtSe2 growth. It is hoped that the thorough investigation of PtSe2 grown by TAC and MOCVD described in this thesis lay a cornerstone for the future adoptions of 2D-PtSe2 in the next generation devices.},
    note = {},
    
    school = {Universität der Bundeswehr München},
    
}