Centimeter-Scale CdS Single-Crystal Nanoscale-Thick Films via Chemical Vapor Deposition for High-Performance Photodetectors

Abstract

Semiconductor single-crystal thin films (SCTFs) with nanoscale thickness play an important role in high-performance electronics and optoelectronic devices, owing to the excellent electrical, optical, thermal, and mechanical performance. Although enormous progress has been made in preparing two-dimensional (2D) material SCTFs, it is still challenging to grow SCTFs based on 3D materials with high efficiency. Herein, we report the efficient growth of centimeter-scale CdS SCTFs with the thickness of ∼95.41 nm on the mica substrates using a chemical vapor deposition method. The controlled experiments and the structure characterizations indicate that the SCTFs are formed by the seamless coalescence of the hexagonal CdS nanosheet domains initially grown in the same orientation on the substrate, with the epitaxial relationship of (100) CdS //(110) mica and (110) CdS //(200) mica . Importantly, the CdS SCTF-based photodetectors (PDs) demonstrate a photoswitching (I on /I off ) ratio up to 10 5 and a fast photoresponse speed (t rise ≈ 0.5 ms, t decay ≈ 1 ms). Furthermore, the PDs exhibit excellent stability to at least 2 months of storage in an ambient atmosphere and 1000-time bending. This work paves the way to synthesizing the 3D semiconductor SCTFs on a large scale and promotes their practical application in multifunctional photoelectric devices.