In this study, we systematically investigate the photoluminescence (PL) spectral changes caused by thermal treatment of hexagonal boron nitride (hBN)-encapsulated MoTe₂ 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 MoTe₂ monolayers, indicating that the excess carriers in 1L-MoTe₂ 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 MoTe₂ monolayers, defect-bound exciton peak intensity is not enhanced even after the thermal treatment in contrast to SiO₂-supported MoTe₂ 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 MoTe₂.

中文翻译：

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热处理减少了六方氮化硼封装的MoTe ₂单层的不均匀扩展

在这项研究中，我们系统地研究了由于热处理而导致的光致发光（PL）光谱变化，该热处理是通过使用聚二甲基硅氧烷进行标准干式转移制造的六方氮化硼（hBN）封装的MoTe ₂单层的。在hBN封装的MoTe ₂单层的20 K的PL光谱中，有一个很强的Trion峰，表明1L-MoTe _2中过量的载流子具有很高的密度。热处理后，由于三重子峰强度的降低以及对激子PL线宽的不均匀贡献，低温下PL谱中会出现一个强而尖锐的中性激子峰。对于hBN封装的MoTe ₂与SiO ₂支撑的MoTe ₂单层相比，即使在热处理后，缺陷结合的激子峰强度也不会提高，因为顶部hBN充当了防止Te原子解吸的覆盖层。结果表明，hBN封装样品的热处理能够同时抑制晶体缺陷的形成和异质界面上的残留物的去除，从而导致电荷转移到MoTe _2上。