Gate-controlled Multispectral Response in Graphene-Based Heterostructure Photodetector

Multispectral photodetectors are crucial for detecting light across a wide wavelength range, serving applications requiring precise wavelength specificity and spectral imaging capabilities. However, the development of these photodetectors is hindered by several challenges, including material compatibility issues, low responsivity, the complexity of signal processing, and precise bandgap engineering. A strategy is proposed using a MoS₂-graphene photodetector to address these issues. Gate-tunable spectral responses are achieved in a graphene photodetector by utilizing carrier transfer from MoS₂ and interfacial gating effects from a SiO₂/p-doped Si substrate. Precise gate bias manipulation enables selective photocurrent capture in the range of 500–680 nm, identical to the absorption of MoS₂. Furthermore, by applying a highly negative gate bias, photocurrent signals below the MoS₂ bandgap, i.e., in the 680–800 nm region, are detected, significantly provoking broadband photodetection. The results highlight the versatility of gate-tunable multispectral response, leading to an exceptional responsivity of up to 1.4 × 10⁵ mA W⁻¹. Moreover, through the precise modulation of gate bias and incident wavelength, it seamlessly switches between negative and positive photocurrents. This study provides important insight into carrier photogeneration in sensitized graphene-based multifunctional optoelectronic devices, establishing a versatile platform for detecting a broad range of photocurrents with a single detector.