An Atomically Thin Air-Stable Narrow-Gap Semiconductor Cr2S3 for Broadband Photodetection with High Responsivity

Infrared (IR) photodetectors are essential for optical communication, imaging, and medical and environmental monitoring technologies. However, current IR photodetectors relying on conventional narrow-gap semiconductors require strict lattice match epitaxy and expensive manufacturing methods, and the incompatibility with complementary metal-oxide-semiconductor technique cannot meet the requirement of high integration and miniaturization. Here, the controllable growth of an ultrathin narrow-gap semiconductor Cr2S3, with thickness down to unitcell of approximate to 1.85 nm, is reported using chemical vapor deposition method. The as-grown 2D Cr2S3 exhibits outstanding environmental stability with negligible degradation even after exposure in air for more than two months. By combining the optics Fourier transfer infrared spectrometer with density functional theory calculations, the bandgap of the synthesized Cr2S3 nanoflakes is determined to be 0.15 eV. A photodetector based on the 2D Cr2S3 exhibits a high responsivity (14.4 A W-1 at 520 nm, 6.0 A W-1 at 808 nm, and 3.0 A W-1 at 1550 nm) and excellent detectivity (4.0 x 10(10) Jones at 520 nm, 1.7 x 10(10) Jones at 808 nm, and 8.3 x 10(9) Jones at 1550 nm) under ambient conditions. These findings indicate that the air-stable 2D narrow-gap semiconductor Cr2S3 can act as a highly competitive candidate for broadband photodetector application and fundamental photophysics investigation.

Automated summary

This study presents the controllable growth of ultrathin narrow-gap semiconductor Cr2S3 using chemical vapor deposition and its excellent environmental stability and high photodetection performance. The bandgap and properties of the synthesized nanoflakes were determined through optics and theoretical calculations, making 2D Cr2S3 a competitive candidate for broad-spectrum photodetection applications in infrared communication and imaging.