Reduced Inhomogeneous Broadening in Hexagonal Boron Nitride-Encapsulated MoTe₂ Monolayers by Thermal Treatment

In this study, we systematically investigate the photoluminescence (PL) spectral changes caused by thermal treatment of hexagonal boron nitride (hBN)-encapsulated MoTe 2 monolayers fabricated by standard dry transfer using polydimethylsiloxane. A strong trion peak is noticeable in the PL spectrum at 20 K of the hBN-encapsulated MoTe 2 monolayers, indicating that the excess carriers in 1L-MoTe 2 have a high density. Following thermal treatment, a strong and sharp neutral exciton peak appears in the PL spectra at low temperatures, owing to the reduction in both the trion peak intensity and inhomogeneous contribution to the exciton PL linewidth. For hBN-encapsulated MoTe 2 monolayers, defect-bound exciton peak intensity is not enhanced even after the thermal treatment in contrast to SiO 2 -supported MoTe 2 monolayers because the top hBN acts as a capping layer for the prevention of the desorption of Te atoms. It is demonstrated that the thermal treatment of hBN-encapsulated samples simultaneously enables the suppression of the crystal defect formation and the removal of the residues at the heterointerfaces, which lead to charge transfer to MoTe 2 .