Fabrication And Optical-electrical Property Investigation Of Manganese-doped Titanium Dioxide Nano-film

Titanium dioxide(TiO2),as a typical wide band-gap semiconductor,has broad application prospects in the field of optics,electrics and magnetism,etc.However,practical applications of intrinsic TiO2 are significantly limited by its low sunlight utilization,electrical conductivity and carrier mobility.Thus researchers have proposed lots of approaches to improve the optical and electrical properties,such as surface modification,hydrogenation and doping,etc.Among them,doping is considered to be one of the most effective ways.Nowadays,TiO2 doping has become a hot topic of the semiconductor oxide field.In this work,we have successfully prepared p-type Mn-doped TiO2(MTO)nano-film on amorphous silica/quartz substrates by radio frequency magnetron sputtering(RFMS)method.The influences of synthesis parameters on the structure and morphology,phase and component ratios,elemental valence and optical-electrical properties were investigated.The main results are as follows:(1)The sputtering power and time has determining affect on the crystallization and thickness of MTO thin films.With the increase of sputtering power and time,thickness and crystallization of the thin films increased.(2)Mn doping resulted in the red shift of XRD diffraction peaks of rutile-TiO2,with the increase of Ar/O2 ratio,the shift decreased.(3)Mn doping could effectively extend the light absorption of TiO2 into visible region,electrical conductivity of the doped thin films has been improved to be 10-2?10-1?-1·cm-1,4-5 orders higher than that of intrinsic TiO2.Hall-effect measurement results suggested that the doped thin films are p-type semiconductors.(4)Rapid thermal annealing at 600? for 1h is harmful for the doped thin films,resulted in Mn separation from the thin films.After the phase separation,the diffraction peaks of the thin films return to the positions of standard rutile-TiO2.The light absorption as well as electrical conductivity decreased accordingly.From which we could conclude that Mn doping is the reason of optical and electrical property improvement of TiO2 thin films.(5)By optimizing the fabrication parameters,the optical and electrical properties of MTO thin films could be largely improved.After optimization,the reasonably good fabricating parameters are as follows:substrate temperature as 550?,working pressure 0.7Pa,Ar flux 50Sccm,O2 flux 1Sccm,sputtering power 120W and sputtering time 2h.The prepared thin films have dark brown color,smooth surface and good optical and electrical properties.It is very important to choose reasonable synthesis parameters when fabricating MTO thin films by sputtering method,since the parameters finally determine the structure and properties of the thin films.Combination of orthogonal test of the parameters and proper annealing conditions is the most appropriate way to develop MTO thin films with good crystallization and optical and electrical properties,perfect processing parameters is still under excavation.