A direct comparison of CVD-grown and exfoliated MoS2 using optical spectroscopy

作者：Plechinger G^*; Mann J; Preciado E; Barroso D; Nguyen A; Eroms J; Schueller C; Bartels L; Korn T

来源：Semiconductor Science and Technology, 2014, 29(6): 064008.

DOI：10.1088/0268-1242/29/6/064008

• MoS2
• Raman spectroscopy
• photoluminescence
• excitons

MoS2 is a highly interesting material, which exhibits a crossover from an indirect band gap in the bulk crystal to a direct gap for single layers. Here, we perform a direct comparison between large-area MoS2 films grown by chemical vapor deposition (CVD) and MoS2 flakes prepared by mechanical exfoliation from mineral bulk crystal. Raman spectroscopy measurements show differences between the in-plane and out-of-plane phonon mode positions in CVD-grown and exfoliated MoS2. Photoluminescence (PL) mapping reveals large regions in the CVD-grown films that emit strong PL at room-temperature, and low-temperature PL scans demonstrate a large spectral shift of the A exciton emission as a function of position. Polarization-resolved PL measurements under near-resonant excitation conditions show a strong circular polarization of the PL, corresponding to a valley polarization.

• 出版日期2014-6