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

Abstract

Interfacial interactions, including interfacial charge transfer and strain, play important roles in the applications of 2D layered materials. Recently, MoO2 have been widely used as precursors or substrates for growth of high‐quality MoS2. Herein, photoluminescence (PL) and Raman spectroscopy are used to investigate the dependence of epitaxial monolayer MoS2 PL properties on MoO2 nanoflakes in different thicknesses on c‐sapphire. On all MoO2 nanoflakes, the trion exciton of MoS2 disappears due to the interfacial charge transfer from MoS2 to MoO2. The neutral exciton of MoS2 exhibits a ≈60 meV redshift on thick MoO2 nanoflakes compared to those either on c‐sapphire or on thin MoO2 nanoflakes, which is attributed to the relaxation of c‐sapphire‐induced compressive strain in MoO2 over a critical thickness. Temperature‐dependent PL measurements reveal a stronger electron–phonon interaction in MoS2 on MoO2 than on c‐sapphire. The findings provide an easy way to tune the properties of MoS2 via tuning the thickness of MoO2 buffer layer on c‐sapphire.