Investigation of the annealing temperature for few-layer MoS2 and ion-beam induced athermal annealing/purification behaviour by in-situ XRD

The synthesis of high-crystalline few-layer MoS2 films is crucial for the development of 2D TMDs (MoS2) based high-performance electrical and optoelectronic devices. The present work reports on a study of thermal annealing and ion-beam induced annealing to improve the crystallinity of few-layer MoS2. According to XRD and TEM measurements, the annealing temperature for few-layer MoS2 in Ar-gas environments was 300 °C, resulting in high crystallinity in a uniform manner. The crystallinity of the few-layer MoS2 decreases as the annealing temperature is increased beyond 300 °C. TEM observations also show that the MoS2 flake size reduces with increasing annealing temperature. In-situ XRD measurements show the ion-beam induced annealing in MoS2 under 120 MeV Au ion-irradiation. The crystallinity improves with lower ion fluence (1 × 1010 ions/cm2), whereas it leads to damage at higher fluences.