Controllable Synthesis And Photoelectric Properties Of Two Dimensional SnS₂ And MoS₂

Due to the selectivity of photoconductive detectors in different wavebands,photodetectors have shown great application in various fields of military and national economy.Van der Waals layered transition metal disulfide(TMD)compounds are of great interest due to their new physical properties in ultrathin limits and are an important candidate for the next generation of electronics and/or optoelectronics.Therefore,this paper is mainly based on the development of a new two-dimensional material,semiconductor material structure regulation and photoelectric detector performance optimization.The main contents are as follows:We report high-performance UV photodetectors established on high quality SnS2 nanoflakes and propose a strategy to address the negative effects of thickness on photoresponsivity for 2D materials.SnS2 nanoflakes with different thickness were mechanically exfoliated from CVT-grown high-quality 2H-SnS2 single crystals.The photodetectors fabricated using SnS2 flakes reveal a desired response performance(R??112 A·W-1,EQE?3.7×104%,D*?1.18×1011 Jones)under UV light with really low power density(0.2 mW·cm-2@365 nm).Most importantly,the responsivity of thin SnS2 flakes(?15 nm)could be heightened to?140 A·W-1 under a positive gate bias of 20 V,reaching the performance level of thicker SnS2 flakes(?60 nm).Thus,our results offer an efficient way to choose 2D crystals with the controllable thicknesses as optimal candidates for desirable optoelectronic devices.In addition,high quality triangular MoS2 flakes were synthesized by chemical vapor deposition(CVD),and a wide road was opened up to promote the application of molybdenum disulfide in the field of optoelectronics by interfacial energy band structure engineering.BaTiO3/MoS2 heterostructures with type I band alignment fabricated by a facile spin-coating method are reported,and their remarkable photodetection performance in comparison with devices based on bare MoS2(R?:120 A W-1 vs 1.7 A W-1 and external quantum efficiency(EQE):4.78×104%vs 4.5×102%@365 nm)is demonstrated.Optical measurements including micro-Raman and photoluminescence(PL)suggest a carrier extraction process accompanied by the carrier injection occurring in the narrower bandgap(MoS2)layer,responsible for the increment of carrier population in MoS2 channel and subsequent improvement of detection ability.