Abstract
Broadband photodetectors in the visible and short-wave infrared wavelengths have garnered significant interest in recent years as a desirable method to achieve better detection in adverse weather conditions. Many material combinations have been proposed to replace expensive III-V based photodetectors; however, the photodetection performance of these novel material and device concepts showed undesirable performances due to uncontrollable charge-trap-based photomultiplication, preventing fast photoresponse and gain. To solve this issue, we devised an engineered potential trap in Ge/MoS2 double junction phototransistor which show a high responsivity of 7.6 A/W (corresponding to an external quantum efficiency of 2,024%) as well as a fast photoresponse of 88.1 µs. The maximum photocurrent gain reaches 29.1 with broadband imaging capability. This excellent performance is achieved through photogenerated hole confined in p-Ge clad by MoS2 and n-Ge induced multiple electrons, which diminished rapidly via recombination upon removal of illumination. Our device concept enables creation of highly sensitive fast broadband imaging based on mixed dimensional van der Waals heterojunctions.
Data availability
The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.
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Funding
This study was supported by the National R&D Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (RS-2024-00438811, RS-2025-00564261, RS-2025-02217113).
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Y.P. fabricated the devices and performed the electrical and optical measurements. H.B.J and H.Y.J performed the material characterizations. Y.P., M.J., S.S., G.Y., and J.H. analyzed the experiments and wrote the manuscript. All authors contributed to the discussion and analysis of the results of the manuscript. J.H. supervised the project.
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Park, Y., Jung, M., Jeong, H.B. et al. Fast photo-carrier multiplication by engineered potential trap in MoS2/Ge double junction phototransistor. Sci Rep (2026). https://doi.org/10.1038/s41598-026-35134-z
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DOI: https://doi.org/10.1038/s41598-026-35134-z
