Photoluminescence nonuniformity from self-seeding nuclei in CVD-grown monolayer MoSe₂

We present optical spectroscopy (photoluminescence and Raman spectrum) studies of monolayer transition metal dichalcogenide MoSe₂, with spatial location, temperature and excitation power dependence. The investigated spectra show location-dependent behavior with an increase in photoluminescence and Raman intensity and a blue-shift in photoluminescence peak position in the inner region. The observed behaviors of a large shift in the photoluminescence peak position at the edge and biexciton emissions in the inner region confirm that the monolayer MoSe₂ crystals grow from nucleation centers during the CVD process. Temperature activated energy and dependence of the peak position are attributed to residual oxygen during the growth. Investigating this information provides a basis for precisely controlling the synthesis of TMDCs and their application in advanced optoelectronics.