Electrical reconfiguration of photodetector frequency response through controlled photoresponse superposition

Adaptive optical communications and sensing require photodetectors whose frequency responses can be reconfigured electronically. Existing strategies commonly switch between different dominant photoresponse mechanisms, while the functional interplay between concurrent mechanisms remains underexplored. Here, a black phosphorus/graphene (BP/Gr) heterostructure photodetector is demonstrated in which photovoltaic and photoconductive contributions coexist under shared optical excitation and exhibit different characteristic frequency roll-offs. Electrical control of their relative sign and weighting enables constructive or destructive superposition, thereby transforming the response between broadband enhancement and frequency-selective detection within the same device. In the constructive regime, a responsivity of 80.5 mA/W and a 3-dB bandwidth of 4.73 GHz are obtained, corresponding to a responsivity-bandwidth product of 3.81 × 10² mA W^-1 GHz under free-space illumination. The device supports optical data reception at 11.318 Gbit/s. In the destructive regime, cancellation between the concurrent response components produces an intrinsic band-pass frequency response with a gate-tunable passband position and out-of-band rejection of up to 36 dB. This frequency selectivity further supports proof-of-concept reception of 5G New Radio signals and suppression of out-of-band interference. Spatially resolved photocurrent mapping under opposite source-drain biases enables even-odd decomposition of bias-retained and bias-induced contributions, revealing their spatial overlap in the BP/Gr heterojunction as well as adjacent device regions. Time-resolved photocurrent measurements further support distinct temporal dynamics associated with the concurrent response components. Together, these results establish controlled superposition of coexisting photoresponses as a route to electrically programmable frequency-domain functionality in two-dimensional optoelectronic devices. The approach highlights how heterostructure materials and interfacial transport can be leveraged to combine high-speed detection with adaptive signal selectivity, without relying on additional external filtering components.