Ultra-high performance MoS₂(Er³⁺)/WS₂(Er³⁺) photodetectors self-assembly synthesized by chemical vapor deposition

Two-dimensional material van der Waals heterojunctions are attractive for integrated optoelectronics, but their performances are largely limited by low carrier concentrations and imperfect layer-transfer technology for layer restacking. Here, high concentration of Er³⁺ ion doped MoS₂(Er)/WS₂(Er) van der Waals heterojunctions are self-assembly synthesized by chemical vapor deposition for ultra-high photodetection. The morphological and optical characteristics of the heterojunctions are characterized in turn by optical and atomic force microscopies, Raman and photoluminescence spectroscopies. 7.9 at.% and 8.6 at.% of Er³⁺ doping concentrations in the heterojunctions are estimated by energy dispersive spectroscopy and X-ray photoelectron spectroscopy, respectively. Photodetectors based on the MoS₂(Er)/WS₂(Er) heterojunctions are prepared, and comprehensively ultra-high photoelectronic performances are achieved, including 422.1 A/W of photoresponsivity (R_λ), 82490% of external quantum efficiency (EQE), and 2.17 × 10¹² Jones of specific detectivity (D*), respectively, which are over twenty times higher than the counterparts of the intrinsic MoS₂/WS₂ heterojunctional photodetectors prepared by layer transfer method. The self-assembly synthesized high-quality vdW heterojunctions combined with high concentration of Er³⁺ doping mark a key notes toward ultra-high performance photodetections.