High-speed and broadband $$\upmu$$ μ TP-heterogeneously integrated InGaAs/GaAsSb photodetectors for next-generation optical interconnects

Abstract As communication rates continue to increase and wavelength-division multiplexing (WDM) becomes ubiquitous, the conventional fiber-optic O and C bands no longer suffice. The 2 $$\upmu$$ μ m wavelength region has emerged as a promising new window in silicon photonics to meet future high-capacity demands and support next-generation optical communication and sensing. Here, we present a high-speed, high-responsivity InGaAs/GaAsSb type-II superlattice (T2SL) photodetector heterogeneously integrated on silicon via micro-transfer printing ( $$\upmu$$ μ TP), achieving broadband operation from 0.8 to 2.5 $$\upmu$$ μ m. By introducing a cavity between backside Au reflector and low refractive index BCB, the broadband responsivity is significantly enhanced with a 57.9% increase at 2 $$\upmu$$ μ m overcoming the conventional trade-off between responsivity and bandwidth. The optimized device demonstrates responsivities of 0.85 A/W at 1.55 $$\upmu$$ μ m and 0.6 A/W at 2.0 $$\upmu$$ μ m, together with 3dB bandwidths of 17 GHz and 18.7 GHz, respectively, approaching the intrinsic carrier transit limit. A clear eye diagram at 50 Gbps further confirms the high-speed performance. These results establish a new benchmark in the responsivity–bandwidth trade-off for broadband photodetectors and demonstrate $$\upmu$$ μ TP as a versatile integration platform for future silicon photonic integrated circuits and optical systems.