Epitaxial growth of large-scale In2S3 nanoflakes and the construction of a high performance In2S3/Si photodetector

Abstract

MoS₂-like layered 2D materials have attracted attention worldwide due to their intriguing material properties. In contrast, it is still a great challenge to prepare non-layered 2D materials that may provide unique electronic and optoelectronic properties compared to layered materials. As an emerging IIIA–VIA semiconductor, In₂S₃ shows great potential for application in optoelectronics. Herein, ultrathin non-layered In₂S₃ nanoflakes, with uniform thickness and lateral size reaching the sub-millimeter scale, are synthesized on mica substrates via a simple physical vapor epitaxy method. Then, a photodetector based on an In₂S₃/Si heterojunction is fabricated. Owing to the strong light–matter interactions of In₂S₃ and the built-in potential at the In₂S₃/Si interface, which accelerates the separation of photoexcited electron–hole pairs, the device exhibits a broadband sensitivity covering the visible to near-infrared region. The responsivity, detectivity and rise/decay time are 579.6 A W⁻¹, 2 × 10¹¹ Jones and 9/0.131 ms, respectively. These performance metrics are among the best values when compared with those of reported layered 2D materials/Si heterojunction photodetectors. Notably, the In₂S₃/Si photodetector suffers from negligible performance degradation even after 1050 cycles of operation or 6 months of exposure to air. These findings broaden the scope of 2D materials and highlight that In₂S₃ nanoflakes hold great potential for further optoelectronic applications.