MoS2 synthesis on fluorine-terminated Si substrates prepared by SF6 mixed gas plasma

Abstract

MoS2 synthesis methods with fewer grain boundaries are expected for device applications. To control the nucleation density and to increase the domain size of MoS2 on a Si substrate, MoS2 was synthesized on a fluorine-terminated Si substrate prepared by SF6 mixed gas plasma. The average domain size of monolayer MoS2 synthesized on a fluorine-terminated Si substrate was several times larger than that on a pristine Si substrate, and grain boundaries were reduced. The MoS2 synthesized on the fluorine-terminated substrate was found to have improved crystallinity based on the results of Raman and photoluminescence spectroscopy. XPS analysis showed that no residual fluoride was observed on the substrate surface after CVD, suggesting that fluorine atoms were volatilized together with Mo by chemical reaction during CVD. Fluorine-terminated surfaces prepared by SF6 mixed gas plasma contribute to increasing the domain size of MoS2, and it can be applied for selective growth in the subsequent CVD synthesis of MoS2.