The Preparation And Optical Properties Of Rare Earth Doped MoS₂ Thin Films

Molybdenum disulfide?Mo S₂?,With a wide range of bandgap,has a broad application in optoelectronic devices,but its conductivity and photoelectric conversion efficiency is low.In this works,rare earth elements were used to improve the photoluminescence efficiency and photoelectric conversion efficiency of MoS₂ materials.Rare earth elements Er,Eu,et.al.with rich electronic energy levels have been widely used in the preparation of high efficiency light-emitting devices and solar cells.The electron band structure and the optical emission spectrum of MoS₂ material will be much expended when it doped rare earth,then the light absorption rate will be further improved,which could be used to fabricate high efficiency thin film solar cells.The optimums experimental conditions for the preparation of rare earth?erbium,europium?doped MoS₂ by chemical vapor deposition were investigated.The effect of doping on MoS₂ film was researched.First,rare earth doped Mo S₂ thin films were prepared on the Si substrate by chemical vapor deposition method using the turbid liquid of MoS₂ and rare earth nitrate as raw material.The surface morphology and crystal structure of doped and undoped films wer e analyzed by atomic force microscopy and X-ray diffractometer.The photoelectric properties of the films before and after doping were analyzed by UV-3600spectrophotometer,photoluminescence instrument and Holzer effect instrument.The influence of growth temperature and time on the surface and photoelectric properties of molybdenum sulfide film was also studied.It was found that the influence of growth temperature and time on the morphology and thickness of the film was significant.The optimum conditions were obtained as follows:the reaction temperature was 650?,the reaction time was 20 min.Then we studied the photoelectric properties of rare earth erbium doped Mo S₂ thin films.It was found that the crystal quality of the doped MoS₂ thin film was significantly improved and the deposition rate was doubled.At room temperature,the absorption of light in the Er:Mo S₂ film increased by 10%in the visible range.The photoluminescence intensity increases by 2 orders of magnitude.Moreover,the short-circuit current and open circuit voltage of erbium-doped MoS₂-Si heterojunction increased by 11.1 times and 1.8times,respectively.The results showed that the use of Er-doped MoS₂ can significantly improve the photoelectric properties.Er:MoS₂ can be used to produce efficient luminescence and optoelectronic devices.In addition,we also studied the photoelectric properties of rare earth europium doped Mo S₂ thin films.Compared with the undoped MoS₂ thin films,the crystallinity of Eu:MoS₂ thin films was improved,the reflectivity decreased,the absorption rate was enhanced,the electrical properties were improved.The light emission intensity of the Eu:MoS₂ thin films was enhanced and produced a red light at room temperature.The open voltage?Uoc?and short circuit current?Isc?of the Eu:MoS₂-Si heterojunction were improved by 6.4 times and 3.2 times,respectively.In summary,the doping of rare earth elements can significantly improve the optical absorptivity,luminescence intensity and the electrical properties of MoS₂ thin films.The research results will have good guides for the preparation of photoconductive devices such as molybdenum sulfide,solar cells and high efficiency light-emitting devices.