Luminescent Properties Of ZnO Nanostructures And Plasma Surface Modification

Zinc oxide(ZnO)is an important third generation semiconductor material because of its unique photoelectric properties and wide application prospects in semiconductor optoelectronic devices.At room temperature,the band gap width is 3.37 eV,and the exciton binding energy is 60 meV,which is much larger than other semiconductor materials.It is expected to achieve stimulated emission at room temperature and obtain a semiconductor laser operating at room temperature.ZnO nanostructures possess the photoelectric properties of ZnO materials as well as the properties of nanomaterials,and have made important progress in the research of lasers,detectors and sensors.Compared with bulk materials,nanomaterials have a large specific surface area,which can greatly improve the performance of nano-devices.At the same time,high surface state density is introduced into the surface of materials,which reduces the recombination efficiency of carriers and thus reduces their luminous performance.Therefore,this study will use Ar~+plasma to conduct surface treatment on ZnO nanostructure,adjust its surface state density,improve its luminescence characteristics,and conduct in-depth study on the influence of Ar~+plasma treatment time and processing energy changes on the luminescence performance of ZnO nanostructure.(1)By chemical vapor deposition method to grow ZnO nanostructures,the ZnO nanostructures under different growth conditions on its surface morphology and optical properties,obtaining the optimal growth conditions:growth temperature is 950?,the growth time is 30 min,Ar gas flow rate is 99 sccm.ZnO nanowires grown under these conditions have the characteristics of good verticality,high density and smooth surface,and have good luminous properties.(2)Ar~+plasma was used for surface treatment of ZnO nanowires,and the relationship between the treatment time of plasma and the luminescence intensity of the nanowires was deeply studied,and the optimal treatment time to improve the luminescence intensity of ZnO nanowires was obtained.The experimental results showed that,with the increase of treatment time,the ambient luminescence intensity first increased and then decreased,which was 2.45 times higher than the original sample at the treatment of 90 s.At the same time,the defect luminescence in the visible region was suppressed.The mechanism of plasma action was analyzed by comparing 10 K emission spectra.When the treatment time was short,Ar~+could effectively remove impurities and defects on the surface of ZnO nanowire and improve its ultraviolet luminescence intensity.However,the surface crystal structure will be destroyed and the luminescence performance will be reduced.This study provides a new way to improve the performance of ZnO-based luminescent devices.(3)ZnO nanowires were treated with Ar~+plasma of different energies to study the influence of plasma treatment of different energies on the luminescence characteristics of ZnO nanowires.Experimental results show that the Ar~+plasma can effectively improve the luminescent properties of nanowires,by 200 W Ar~+plasma treatment after 90 s,the luminous intensity of ZnO nanowires and without Ar~+plasma treatment increased compared to the luminous intensity of 60 times,by 200 W Ar~+plasma treatment ZnO nanowires after ten days after measurement,found that the light stability is good.This part of the work shows that simple and effective plasma treatment can greatly improve the luminous performance of ZnO nanowires.