Study On The Preparation And Application Of 3d Transition Metal Doped Cu₃N Films By Magnetron Sputtering

It has been studied the effect of doping with 3d transition metals on the structure and optical properties of copper nitride(Cu3N)films,and the special changes given by Mn doping is focused.Then in order to improve the magnetism of Cu3N,V,Cr and Mn are selected as the dopants.It is concluded that Cr doping contributes greatest to the magnetic moment of Cu3N.Inspired by the particular optical-electrical characteristic of Mn doped Cu3N films,we have acquired a new visible photodetector based on Cu3N films.At last,on account of write-once optical storage application of Cu3N,the write-once optical storage capacity is enhanced by introducing a dense oxide protective layer.There are four main contents in the text as fllows:Firstly,3d transition metals doped Cu3N films have been prepared using magnetron sputtering,the preferred orientation of Cu3N film is changed from(111)to(100)after inserting with Sc,Ti and V,which reduce the Cu participated in reaction,resulting in a N-rich grown condition.The(111)peaks of Cu3N film are kept on in spite of(100)peaks occured by doping with Cr,Mn and Fe,as a result of more 3d electron of dopants.While for the Co and Ni doping,the films grow with the same(111)preferred orientation with undoped Cu3N film,and the(111)peaks are stronger,which could be attributed to the most 3d electron of Co and Ni dopants,bonding capability of Cu3N is enhanced by ionic bond of Cu-N.The influences on the optical-electrical properties of Cu3N film are different for diverse 3d transition metals dopants.In general,the more 3d electron of metal dopant,the more tend to conductor nature of Cu3N film,which obtain decrescent optical band gap and better conduction.Unusually,Mn doped Cu3N give an individual variation trend,the increased band gap and resistance making a sensitive for visible light.Secondly,we have useed reactive magnetron sputtering to fabricate pure copper nitride(Cu3N)and V,Cr and Mn doped Cu3N films that all grow along with the preferred orientation of(100)and(200)which is the N-rich crystal face.As a result,the doping samples exhibit different peak shifts(Cr:to lower angle,V and Mn:to larger angle)and diverse surface morphology,the band gap have been changed after doping(V and Cr:1.50 to 1.22 eV,Mn:1.50 to 1.56 eV).According to theoretical results,TM in center vacancy of Cu3N can improve magnetic properties more effectively than that of TM in Cu vacancy of Cu3N.And Cr doping in center give the biggest magnetic moment of 0.2656 ?B.This experiment also provided a method to implement the energy gap and magnetism modulation of Cu3N films by doping with magnetic transition metal(V,Cr and Mn).Thirdly,for the first time we demonstrated the synthesis of high-quality Mn doped Copper nitride(Cu3N)films via DC magnetron sputtering method and explored their applications in visible photodetectors.The as-synthesized Mn doped Cu3N films are crystalline films with a suitable optical absorption in the visible region,which show an indirect bandgap of ? 1.47 eV greater than an indirect bandgap of un-doped Cu3N films(1.29 eV).Impressively,photodetector based on Mn doped Cu3N films exhibits remarkable performance,including a high responsivity(?2),a fast response rate(less than 0.1 s both for rise and decay time),superior to the un-doped Cu3N films based photodetectors.The regarded excellent optoelectronic properties reflect a good tradeoff between responsivity and response rate and suggest that Mn doped Cu3N films have a high promise for future photodetection.Fourthly,the design and construction of an enhanced write-once optical storage devices based on the Cu3N films with the Al2O3 protective layer were studied.The memory devices exhibited typical write-once-type memory characteristics with different size of "IAM" letters matrix(40,20,and 10 ?m).After coupling with the Al2O3 protected layer,the storage capacity of Cu3N film can be improved greatly by restricting aggregation.Furthermore,the proposed mechanisms for the recording process may also provide some ideas for the future design of enhancing write-once optical storage capacity of write-once optical storage devices base on Cu3N.