Size-Dependent Mutual Charge Transfer between B- and P-Codoped Si Quantum Dots and Monolayer MoS2

Heterostructures built from two-dimensional (2D) transition metal dichalcogenide (TMD) monolayers and quantum dots (0D) offer a large variety of systems for probing the fundamental physics and for the device applications. In this work, 2D/0D heterostructures comprised of monolayer MoS2 (1L-MoS2) and Si quantum dots (QDs) are produced and the mutual charge transfer is studied. It is shown that the charge transfer property depends strongly on the size of Si QDs. Decoration of a 1L-MoS2 flake with Si QDs with a diameter of 3.5 nm results in the quenching of the PL, while the decoration with Si QDs with a diameter of 9.0 nm enhances it. The results indicate that the direction of the charge transfer is different depending on the Si QD diameter. Contributions of the A excitons, B excitons, biexcitons, and trions to the total PL spectra are analyzed in a wide excitation power range, and the mechanism of the charge transfer is discussed.