Unveiling the origin of two distinct routes of interlayer charge transfer doping in Bi₂Te₃/MoS₂/SiO₂ heterostructure

Understanding the charge doping and thermal heating effects in atomically thin transition metal dichalcogenides is of critical importance as the management of both is required in designing efficient low-dimensional optoelectronics. Here, we investigate interlayer charge transfer doping and thermal heating effects in monolayer MoS₂ under the influences of not only the SiO₂/Si substrate but also a topological insulator Bi₂Te₃ film. Simultaneous Raman correlation and photoluminescence analyses reveal charge transfer doping and thermal heating regimes with an increase of excitation laser power. Particularly, two distinct types of charge transfer phenomena are observed. Photo-induced electron transfer takes place at the interface between the monolayer MoS₂ and SiO₂/Si substrate. Then in the presence of Bi₂Te₃, besides the photo-induced electron transfer from SiO₂ to MoS₂, the overall electron density in MoS₂ is remarkably increased. Electronic structure calculations for MoS₂/SiO₂ and Bi₂Te₃/MoS₂/SiO₂ provide direct evidence of the two types of charge transfer phenomena and strongly support the Raman and photoluminescence results. As a result, our work demonstrates that a parallel study of Raman scattering, photoluminescence, and relevant theory can provide valuable insights into the interlayer charge transfer mechanism in various two-dimensional heterostructures.