Unique and Tunable Photodetecting Performance for Two-Dimensional Layered MoSe2/WSe2 p–n Junction on the 4H-SiC Substrate

MoSe₂/WSe₂ two-dimensional transition-metal dichalcogenide (TMDC) heterojunction photodetectors based on epitaxial n-doped 4H-silicon carbide (SiC) substrate are investigated and exhibited low leakage, high stability, and fast photoresponse. The efficient separation of photogenerated carriers occurs between TMDCs and 4H-SiC, as indicated by the photoluminescence spectrum and the band alignment analysis under 532 nm. The MoSe₂/WSe₂/4H-SiC photodetector shows an obvious rectification behavior and unique current-gate voltage ( I- V_g) characteristics. The gate tunable photocurrent scanning maps display the highest photocurrent in the MoSe₂/WSe₂ region including a certain intensive current region in individual TMDCs/4H-SiC junctions under a 532 nm laser. Besides, the maximum responsivity of the heterojunction photodetectors is 7.17 A·W^-1 with the V_g of 10 V at positive bias. The corresponding maximum external quantum efficiency and detectivity also significantly increase to 1.67 × 10³% and 5.51 × 10¹¹ jones with the largest I_light/ I_dark ratio of ∼10³. Moreover, the MoSe₂/4H-SiC photodetector delivers an enhanced photoresponse behavior with gate modulation, which is different from the previous paper. These results of our study demonstrate that MoSe₂/WSe₂ heterojunction photodetectors based on the n-doped 4H-SiC substrate will be a promising candidate for future optoelectronics applications in spectral responsivity.