Band Structure-Engineered Nanopatterned MoS2/Graphene Heterostructures for Low-Noise Broadband Photodetection

Abstract

Integrating two-dimensional (2D) heterostructures is a promising strategy for high-performance optoelectronics; however, achieving high sensitivity and broadband response while maintaining low-noise operation remains challenging. Here, we report a nanoporous molybdenum disulfide (MoS2)/graphene heterostructure phototransistor fabricated via block copolymer-assisted self-assembly and material-selective etching, which provides a scalable and reproducible approach for large-area fabrication. By employing a precise etching sequence using O2 plasma for graphene and XeF2 gas for MoS2, we successfully realize a periodic nanohole array while preserving interfacial integrity. The resulting nanoporous architecture induces bandgap opening in graphene and introduces a high density of edge states, which enhances trap-assisted photogating in the phototransistor and significantly amplify the photocurrent. As a result, the device exhibits a high photoresponsivity of 24.58 AW–1 and a specific detectivity of 2.33 × 1011 Jones under 405 nm illumination. Notably, the device demonstrates a robust photoresponse in the mid-infrared (MIR) region (≈11 µm), extending beyond the intrinsic bandgap limitation of MoS2 and enabling detection capability spanning from the visible to the MIR regime, compared with previously reported MoS2-based heterostructures operating over narrower spectral ranges. Temperature-dependent measurements confirm that this MIR response originates from genuine optical carrier generation rather than bolometric effects. Furthermore, the nanoporous graphene suppresses excessive dark current via bandgap opening and edge-induced states, enabling improved signal-to-noise characteristics. These results establish nanoporous 2D heterostructures as an effective strategy for ultra-broadband and low-noise photodetection.