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

Abstract

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 In2S3 nanosheets on a pyramidal Si array surface and develop the In2S3/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 In2S3 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 In2S3 and Si at the junction. As a result, the In2S3/Si heterojunction photodetector has a detectivity of ∼ 1.04 × 1014 Jones, a responsivity of ∼ 200 A W−1, a sensitivity of ∼ 1.74 × 105 cm2 W−1, and a rise time/delay time of ∼ 72/415 µs. We prospect that large-scale synthesis of vertically standing In2S3 nanosheets/pyramidal Si array heterojunction has immense potential in energy and material development, biomedicine, and other applications.