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

Abstract

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- Vg) 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 Vg 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 Ilight/ Idark 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.