A Study of Exfoliated Molybdenum Disulfide (MoS_2) Based on Raman and Photoluminescence Spectroscopy

摘要

In this study, we demonstrate mono and a few-layered MoS_2 samples on an SiO_2(270 nm)/Si substrate from bulk MoS_2 crystal by a micromechanical exfoliation technique. For unambiguous layer number identification, experiments have been carried out with a unified complementary approach based on optical microscopy, atomic force microscopy, resonant Raman spectroscopy, and photo-luminescence spectroscopy. The experimental analysis was carried out on a statistically significant of mono and a few-layered MoS_2 flakes (from one to ten layers) on the SiO_2(270 nm)/Si substrate. Identification of the MoS_2 layer number based on a quantitative analysis of resonant Raman and PL spectra is proposed. Results showed that first, the Raman intensity area ratio of the MoS_2 E_(2g)~1, A_(1g) and 2LA modes to that area of the Si substrate increased linearly with increasing number of layers of MoS_2. Second, the normalized PL intensity area of the (A) peak decreased linearly with increasing number of layers of MoS_2.