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

Abstract

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.