Spectrally decoupled, signal-boosted photodetection via vertical 2D/3D heterointegration for non-invasive biosignal monitoring

Abstract

Heterogeneously integrated photodetectors (PDs) offer a promising platform for non-invasive biosensing, yet existing organic systems often struggle with spectral crosstalk and reliability issues. Here, we report a spectrally decoupled, 2D/3D inorganic heterointegrated PD (HI-PD) platform realized by vertically stacking WS2/MoS2 monolayers onto a silicon (Si) PD. The interface-driven modulation achieves a staggered Type-II band alignment, boosting the photocurrent by 982% compared to monolayer MoS2. The vertically integrated HI-PD enables precise multispectral detection by selectively absorbing red light in the top TMD layer while allowing infrared (IR) light to reach the underlying Si-PD. This system exhibits an exceptional signal-to-noise ratio (SNR) of 14.5 dB for red light (a 221% increase over conventional Si-PDs) and a 23-fold higher SNRarea than previously reported PDs. We successfully demonstrate real-time monitoring of heart rate and blood oxygen saturation (SpO2), providing a scalable van der Waals heterostructure paradigm for next-generation personalized healthcare.