Large-Scale Synthesis of Vertically Standing In2S3 Nanosheets/Pyramidal Silicon Array Heterojunction for Broadband Photodetectors

Two-dimensional (2D) materials are significant in the next generation of optoelectronics due to their unique advantages such as thickness-tailored band gaps, mechanical flexibility, and high carrier mobility. However, the conventional fabrication of large-scale and high-quality 2D materials is a laborious complication, thus limiting their wide application. Here, we demonstrate the large-scale fabrication method of vertically standing In 2 S 3 nanosheets on a pyramidal Si array surface and develop the In 2 S 3 /Silicon (Si) heterojunction photodetector with a wide-spectrum response from 365 nm to 980 nm. The efficient photoelectric conversion of heterojunction is attributed to the enhanced light absorption ability of pyramidal Si and vertically standing In 2 S 3 nanosheets due to the large specific surface-to-volume ratio and the multiple light reflections, and the interface barrier originated from the difference of Fermi level between In 2 S 3 and Si at the junction. As a result, the In 2 S 3 /Si heterojunction photodetector has a detectivity of ∼ 1.04 × 10 14 Jones, a responsivity of ∼ 200 A W −1 , a sensitivity of ∼ 1.74 × 10 5 cm 2 W −1 , and a rise time/delay time of ∼ 72/415 µs. We prospect that large-scale synthesis of vertically standing In 2 S 3 nanosheets/pyramidal Si array heterojunction has immense potential in energy and material development, biomedicine, and other applications.