Author, Institution: Šarūnas Jankauskas, Kaunas University of Technology
Science area, field of science: Technological Sciences, Materials Engineering, T008
Research supervisor: Chief Researcher Dr. Šarūnas Meškinis (Kaunas University of Technology, Natural Sciences, Physics, N002)
Research consultant: Senior Researcher Dr. Rimantas Gudaitis (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)
Dissertation Defence Board of Materials Engineering Science Field:
Prof. Dr. Hab. Arvaidas Galdikas (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008) – chairperson
Prof. Dr. Eva Kovacevic (University of Orléans, France, Technological Sciences, Materials Engineering, T008)
Prof. Dr. Giedrius Laukaitis (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)
Prof. Dr. Alvydas Lisauskas (Vilnius University, Natural Sciences, Physics, N002)
Prof. Dr. Liutauras Marcinauskas (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)
Dissertation defence meeting will be at Rectorate Hall of Kaunas University of Technology (K. Donelaičio 73-402, Kaunas)
The doctoral dissertation is available at the library of Kaunas University of Technology (Gedimino 50, Kaunas) and on the internet: Š. Jankauskas el. dissertation.pdf
© Š. Jankauskas, 2026 “The text of the thesis may not be copied, distributed, published, made public, including by making it publicly available on computer networks (Internet), reproduced in any form or by any means, including, but not limited to, electronic, mechanical or other means. Pursuant to Article 25(1) of the Law on Copyright and Related Rights of the Republic of Lithuania, a person with a disability who has difficulties in reading a document of a thesis published on the Internet, and insofar as this is justified by a particular disability, shall request that the document be made available in an alternative form by e-mail to doktorantura@ktu.lt.”
Annotation: In this doctoral dissertation, the direct horizontal synthesis of graphene on catalytic-free substrates (Si, SiO₂, Al₂O₃(0001), and h-BN/SiO₂) commonly used in microelectronics and optoelectronics is investigated using microwave plasma-enhanced chemical vapor deposition (MW-PECVD). A steel protective cap was successfully implemented in this work to reduce the undesirable plasma effects on the substrate and the growing film. Utilizing Raman spectroscopy and atomic force microscopy (AFM), the influence of synthesis parameters (gas flow ratio, pressure, and temperature) on the morphology, defect density, and structure of nanocrystalline multi-layer graphene films was determined. Furthermore, the critical lower-temperature limits (<600 °C) for synthesis were defined, opening new pathways for the integration of graphene into standard CMOS technology. Furthermore, the suitability of the directly grown graphene for electronic device fabrication was demonstrated. The functional properties of the developed graphene/Si photodiodes and biological sensors operating on the graphene field-effect transistor (G-FET) principle were investigated. It was found that the insertion of a dielectric hexagonal boron nitride (h-BN) underlayer doubles the short-circuit current and photocurrent of the photodiodes due to reduced surface carrier recombination, while the fabricated biological sensors exhibit high sensitivity.