High-speed and broadband spectral photodetectors based on β-In2Se3/Si heterojunction

Two-dimensional Indium selenide (2D In2Se3), a direct band gap semiconductor in group III-VI, shows a potential application in constructing novel photodetectors with broadband spectral response. The device performances of these In2Se3-based photodetectors are limited by synthesis of the large-scale In2Se3 with high crystal quality and optimization of device structure and constructing process. Herein, a vertical β-In2Se3/Si p-n heterojunction is reported by in situ depositing a β-In2Se3 film with high quality on Si substrate by pulsed laser deposition technique. The resultant β-In2Se3/Si p-n heterojunction showed a broadband spectral response range from 265 nm to 1300 nm with a high responsivity up to 6.4 AW-1 at bias of −2 V. More importantly, a high response speed approaching to 2.2 μs at zero bias is achieved, which are much better than most of previous III-VI/Si based photodetectors and some of 2D layered transition metal dichalcogenides (TMDCs)/Si heterojunction. Moreover, the responsivity for 1300 nm NIR light is as large as 0.12 AW-1, which is superior than most of previous Si compatible 2D-3D heterojunction. The results suggest that our work paves the way toward the construction of novel III-VI/Si 2D-3D heterojunctions for high-performance and broadband photodetectors.