Exciton properties for MoS2 grown with the horizontal and vertical orientation

Abstract

The exciton properties play a crucial role in controlling the optical properties of molybdenum disulfide (MoS2). In this work, horizontally oriented MoS2 (H-MoS2), horizontally and vertically oriented MoS2 (HV-MoS2), and vertically oriented MoS2 (V-MoS2) on the same SiO2/Si substrate have been synthesized and investigated using temperature-dependent photoluminescence spectroscopy from 7 to 300 K. Except for direct excitons called as A and B peaks, indirect exciton named as I peak is discovered with the splitting of three peaks. Compared with direct excitons, indirect excitons appear to be more susceptible to the orientation of MoS2. The exciton activation energies are larger, and the exciton–phonon coupling is stronger in V-MoS2 than in H-MoS2. The exciton properties of HV-MoS2 are more similar to those of V-MoS2, but there are some unusual phenomena. Our work provides a reference for optoelectronic applications based on transition-metal dichalcogenides represented by MoS2 grown with horizontal and vertical orientations.