Multiscale Design and Simulation of CdSe/ZnS/MoTe₂ Hybrid Photodetectors

Two-dimensional MoTe₂ is applicable for near-infrared photodetection; however, low absorption in the visible range limits its performance. One way to overcome these limitations is by hybridizing with light-absorbing nanomaterials. In this study, we simulate a CdSe/ZnS quantum dot (QD)-sensitized MoTe₂ photodetector at the coupled electromagnetic and device level. COMSOL Multiphysics demonstrates that the heterostructure of MoTe₂/CdSe/ZnS on a SiO₂/Si substrate exhibits a broadband-visible enhancement in absorption due to QD exciton absorption and Fabry-Perot interferences in the silicon dioxide layer. A staggered type-I band alignment of the CdSe/ZnS/MoTe₂ interface was confirmed by COMSOL analysis, which also permits interfacial charge separation. Simulations of QD integration by Silvaco technology computer-aided design reveal that QD integration increases photocurrent through photogating and carrier transfer. The optimized device has a responsivity and detectivity of 1.3 × 10^-3, 2 × 10^-3 A/W, 9.4 × 10⁸, and 1.34 × 10⁹ Jones, and an external quantum efficiency of 0.31% and 0.394% at 520 and 630 nm, respectively, which is significantly better than pristine MoTe₂ photodetectors. These results demonstrate the potential of CdSe/ZnS/MoTe₂ heterostructures for high-performance broadband photodetection and establish a framework for correlating multiscale simulations with material properties and device performance.