CVD Growth and Integration of 2D-MoS₂ for Advanced Heterostructures

PhD thesis investigates the chemical vapor deposition (CVD) growth and integration of two-dimensional (2D) molybdenum disulfide (MoS₂) on different substrates, including SiO₂/Si, GaN and β-Ga₂O₃, with the aim of advancing its application in hybrid optoelectronic and photonic devices. The research focuses on understanding how substrate properties and growth conditions influence the nucleation dynamics, morphology, strain and properties of MoS₂, as well as on developing reproducible processes for its large-scale integration. An optimized liquid-precursor CVD process was developed using ammonium heptamolybdate or sodium molybdate in combination with sulfur powder, enabling the growth of triangular MoS₂ monolayers exceeding 100 μm in lateral size. In addition, a PMMA-assisted deterministic transfer process was established and refined to minimize polymer residues and preserve the optical quality of the monolayers. A comprehensive characterization framework, combining scanning electron microscopy (SEM), atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), Raman spectroscopy, photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), was employed to correlate morphology, size, strain, doping and interface coupling. The results highlighted the key role of substrate surface in determining the crystalline quality and optical response of MoS₂. This was further validated through the fabrication of a prototype MoS₂/GaN hybrid device.