Fig. 2

a (i) Schematic cross-section view of the h-BN/WS\(_2\)/SiO\(_2\) sample. (ii) Normalized PL images showing the emission of charged excitons under applied bias voltages V\(_{\text {ext}}\) \(=\) +60 V and V\(_{\text {ext}}\) \(=\) −60 V, respectively. (iii) Average shift of the center position of the spatial profiles of the PL emission as a function of decay time at different applied bias voltages. (iv) Drift distance of charged excitons as a function of decay time. b (i) Schematic diagram illustrating the generation and behavior of photogenerated neutral and charged excitons in MoS\(_2\), depending on gate voltage (V\(_\text {g}\)). Normalized PL images depicting diffusion patterns of neutral and charged excitons at V\(_\text {g}\) \(=\) −20 (ii), 0 (iii), and 20 V (iv), respectively, under a pump fluence of 75 \(\mu\)J cm\(^{-2}\). c (i) Single-gate dependence analysis revealing the formation of charged interlayer excitons with varying carrier density. (ii) Decay times for charged interlayer excitons as a function of single gate bias voltage. (iii) Optical image showcasing the device with false-colored top gates covering the overlaid WSe\(_2\) and MoSe\(_2\) heterostructure. (iv) Spatial dependence of PL intensity normalized according to I\(_{\text {PL}}\)(V\(_{\text {ds}}\))/I\(_{\text {PL}}\)(V\(_{\text {ds}}\) \(=\) 0) for V\(_{\text {ds}}\) \(=\) −3 V. (v) Normalized I\(_{\text {PL}}\) averaged over the y axis versus the heterostructure channel length x for different V\(_{\text {ds}}\). a Reproduced with permission [20]. Copyright [2021] Americal Chemical Society. b Reproduced with permission [18]. Copyright [2020] Americal Chemical Society. c Reproduced with permission [21]. Copyright [2019] AAAS