Low-temperature Growth And Properties Of The ZnS Thin Films

ZnS is an important compound semiconductor with a wide band gap.The preparation and investigation of high-quality ZnS thin films are one of the key factors affecting their application of thin-film devices.In this paper,Zn thin films were deposited on the glass substrates at room temperature by magnetron sputtering.And then these Zn thin films were preheated at 200? and subsequently annealed in an atmosphere of sulfur-vapor and Ar to form ZnS thin films.The properties of the samples were analyzed by XRD(X-ray diffractometer),SEM(scanning electron microscopy),EDS(Energy Dispersive Spectrometer)and UV-VIS spectrophotometer.Effects of sulfidation temperature,sulfidation time and deposition time of Zn on the structure,morphology,composition and optical properties of resultant films were investigated.Sputtered Zn thin films were preheated at 200? for 1h and subsequently annealed at various temperatures for 1h in sulfur-vapor.It was also found that the initial preheating at200? led to the formation of ZnS on the Zn film surface,and sulfidation temperature in the subsequent annealing had an obvious effect on the optical transmittance,S/Zn atomic and crystalline of the sulfurized thin films.ZnS thin films prepared by sulfidation at a temperature greater than or equal to 300?,with hexagonal structure and band-gap energies from 3.54 e V to 3.60 e V,exhibited the optical transparency of about 80% in the400-1100 nm region.Sputtered Zn thin films were preheated at 200? and subsequently annealed at a low temperature of 400?.Too short preheat time or sulfidation time and too long preheat time or sulfidation time were found to result into the poor qualities of the resultant ZnS thin films.The appropriate preheat time and sulfidation time of Zn thin films were all 1h.Zn thin films were deposited for different time by magnetron sputtering.And then these Zn thin films were preheated at 200? for 1h and subsequently annealed at 400?for 1h in sulfur-vapor.The results showed that with increasing deposition time of Zn,the grain size,optical transmittance,band-gap,and S/Zn atomic ratio of ZnS thin films were obviously changed with different trends.Also,the low-temperature sulfidation mechanism of these ZnS thin films was discussed.Besides,evacuation before sulfidation was observed evidently to improve the qualities of ZnS thin films.All ZnS thin films exhibit the optical transparency of about 70% in the 400?1100nm region.The best quality ZnS thin films were prepared by an evacuation,followed by 200 ? preheat(1h)and subsequently 400? sulfidation(1h)of the 3min-deposited Zn.