Laser-Induced Oxygen Engineering for Localized Homojunction Formation in SnS2 Photodetectors

Abstract

The development of high-performance optoelectronic devices based on 2D materials has attracted significant attention. However, conventional vertical stacking methods are limited by complex processes and interfacial defects. To overcome these challenges, we propose a simple and efficient one-step process to form an in-plane homojunction within a single n-type tin disulfide (SnS2) flake via direct laser irradiation. The core process, oxidative thinning, utilizes a focused 532 nm laser to locally convert a portion of SnS2 into tin oxide (SnOx). Consequently, an energy barrier arising from a work-function difference of approximately 0.7 eV is formed at the interface, promoting the separation of photogenerated electron-hole pairs. The fabricated photodetector demonstrates a fast response time (tau r/tau f = 474/299 ms), an improvement of several tens of times compared with the pristine SnS2 device. Furthermore, it exhibits a high responsivity (R) of 703 mA W-1, an external quantum efficiency (EQE) of 170%, and a remarkable specific detectivity (D*) of 2.35 x 1014 Jones, along with excellent operational stability. This laser-induced local conversion technique presented can provide a powerful and practical platform for developing next-generation flexible and wearable optoelectronic devices.