Interfacial Effects on the Photoluminescence Properties of Epitaxial Monolayer MoS2 on MoO2 on C‐Sapphire

Interfacial interactions, including interfacial charge transfer and strain, play important roles in the applications of 2D layered materials. Recently, MoO 2 have been widely used as precursors or substrates for growth of high‐quality MoS 2 . Herein, photoluminescence (PL) and Raman spectroscopy are used to investigate the dependence of epitaxial monolayer MoS 2 PL properties on MoO 2 nanoflakes in different thicknesses on c‐sapphire. On all MoO 2 nanoflakes, the trion exciton of MoS 2 disappears due to the interfacial charge transfer from MoS 2 to MoO 2 . The neutral exciton of MoS 2 exhibits a ≈60 meV redshift on thick MoO 2 nanoflakes compared to those either on c‐sapphire or on thin MoO 2 nanoflakes, which is attributed to the relaxation of c‐sapphire‐induced compressive strain in MoO 2 over a critical thickness. Temperature‐dependent PL measurements reveal a stronger electron–phonon interaction in MoS 2 on MoO 2 than on c‐sapphire. The findings provide an easy way to tune the properties of MoS 2 via tuning the thickness of MoO 2 buffer layer on c‐sapphire.