Horizontal to vertical growth of MoS2 from amorphous thin films controlled by tuning repetition rate of pulsed KrF laser during deposition

The preparation conditions of amorphous and crystalline thin films determine their physical properties and potential applications. In this work, we demonstrate the role of the repetition rate (1, 3, 5 and 10 Hz) of KrF pulsed laser in pre-configuring amorphous MoS 2 thin films and governing their subsequent crystallization. We show that while the composition of as-deposited amorphous MoS 2 thin films are stoichiometric in all cases, the amorphous MoS 2 thin film deposited at 1 Hz exclusively transforms in the preferentially layered phase along the (002) Bragg reflection compared to higher repetition rates which gradually suppress the out-of-plane growth and the dominant reflection becomes along (010) characterizing the vertically oriented basal planes. This inverted growth character is further confirmed via Raman spectroscopy, where a significant increase in the A 1 g / E 2 g 1 intensity ratio correlates with the transition to vertical alignment, and by the SEM microscopy, which directly reveals the vertical morphology. The transition from horizontal to vertical alignment is also reflected in the valence band structure probed by X-ray photoelectron spectroscopy (XPS), demonstrating that XPS can serve as a rapid and practical screening tool for determining MoS 2 orientation. Furthermore, XPS analysis reveals that the prevalence of 1 T ′ -like motifs in the amorphous phase acts as a key factor promoting vertical growth.