Universität zu Köln

Fauzi, Billy Oktora Abdilah ORCID: 0000-0003-0269-0570 (2026). From Precursor Engineering to Material Synthesis: Mixed-Ligand Al, Ga, Zr, and Hf Complexes for Chemical Vapor Deposition. PhD thesis, Universität zu Köln.

PDF Dissertation_Billy Fauzi_2026.pdf - Accepted Version Download (17MB)

Abstract

In the era of rapidly advancing technologies, the demand for high-performance semiconductor thin films continues to increase, driven by applications in microelectronics, energy systems, sensing devices, and emerging quantum technologies. Ongoing device miniaturization and the need for higher efficiency require thin films with precise control over thickness, composition, crystallinity, and interface quality. Consequently, the development of scalable and reliable fabrication techniques has become a central focus in materials science and semiconductor research. Atomic layer deposition (ALD) is widely used for thin film fabrication due to their ability to produce uniform and high-quality layers. However, ALD is inherently slow because of its sequential surface reactions. This factor can restrict throughput and increase production costs for large-scale manufacturing. Metal-organic chemical vapor deposition (MOCVD) offers a promising alternative, combining high deposition rates, compositional tunability, and compatibility with industrial-scale processes. Nevertheless, MOCVD relies on the availability of suitable precursor chemistry that remains a critical challenge. Precursors chemically designed to match the material composition and simplified the chemical input to the thin film growth are termed as single-source precursors (SSPs). SSPs are particularly advantageous because all required film-forming elements are incorporated within a single molecular framework, enabling precise stoichiometric control and minimizing gas-phase side reactions. The rational design of metal-organic precursors is therefore essential, as their molecular structure influences volatility, thermal stability, and decomposition behavior during film growth. An effective precursor design integrates coordinative saturation of the metal center with thermal lability of ligands enabling low decomposition temperature. This dissertation focuses on the application of novel aluminum, gallium, zirconium, and hafnium complexes in MOCVD. These precursors were developed for the deposition of technologically relevant materials, including zirconium oxynitride (ZrON), hafnium zirconium oxide (HfxZr1-xO2, HZO), and aluminum gallium oxide ((AlxGa1-x)2O3). These materials are of significant interest due to their dielectric, ferroelectric, and ultra-wide bandgap semiconductor properties, which are relevant for next-generation memory, power electronics, and optoelectronic applications. Both homoleptic and heteroleptic complexes based on alkoxide (–OR-) and fluorinated β-ketoenaminate (–N^ORF-) ligands were synthesized and structurally characterized. The presence of –CF3 groups in the ligand backbone enhances volatility and thermal stability by reducing intermolecular interactions, while the chelating β-ketoenaminate framework (N^O) stabilizes the metal center and promotes controlled decomposition pathways. Importantly, the resulting complexes form solid-state compounds that can be purified efficiently by low-pressure sublimation, ensuring high purity and ease of handling. The interplay of steric and electronic effects is evident in both main group (Al, Ga) and transition metal (Zr, Hf) compounds. Al and Ga preferentially form tetrahedral complexes, only one chelating β-ketoenaminate unit could be incorporated in the coordination sphere of Al and Ga complexes. In contrast, Zr and Hf formed octahedral complexes, allowing an introduction of two β-ketoenaminate ligands to form a series of stable compounds. This dissertation reports precursor synthesis, structural characterization, thermal properties, and vapor-phase behavior, followed by evaluation of their performance in MOCVD processes. By correlating molecular design with thin film growth behavior and material properties, the study establishes structure-property relationships that guide the development of advanced SSPs.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Fauzi, Billy Oktora Abdilah billyfauzi@gmail.com https://orcid.org/0000-0003-0269-0570 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-814481
Date:	2026
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry
Subjects:	Chemistry and allied sciences
Uncontrolled Keywords:	Keywords Language Precursors UNSPECIFIED metal-organic chemical vapor deposition UNSPECIFIED Thin films UNSPECIFIED
Date of oral exam:	4 September 2026
Referee:	Name Academic Title Mathur, Sanjay Prof. Dr. Dr. (h.c.) Klein, Axel Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/81448