Optical And Electrical Properties Of Mn-(Co,Zn,Fe)-Ni-O Series Thin Films

Transition metal oxides show abundant physical properties,due to incomplete occupation d orbit and electron correlations,such as metal-insulator transition,high-temperature superconductivity,multiferroics,ferromagnetism,giant magneto resisive effect,resulting in attracting many scientist's attentions.Among the transition metal oxides,manganese oxides are widely applied for negative temperature coefficient thermistor,photocatalysis,automobile's exhaust detection and humidity sensor.With the developing dramatically of computer,thermistor and signal transmission,temperature sensor trend to intelligentialize,microminiaturization,thin-film technique,fast response,high stability and environmentally friendly design.Therefore,it's urge to research thin film technique,to keep up with the pace of the times.In this thesis,we synthesize three kinds of thin films,used by chemical solution deposition and RF magnetron sputtering.We study the different sputtering powers,doping concentration and annealing temperature to control the property of thin films.Detail results as follow.?1?We synthesize Mn_1.56Co_0.96-xNi_0.48Fe_x O₄?x=0,0.15,0.2?series thin film by chemical solution deposition method.It finds that Fe-doping can improve the microstructure and density.What's more,residual absorption at the wavelength of 19 um is firstly found,used by the IR spectroscopic ellipsometer.?2?We synthesize Mn_1.5Co₂Fe_2.1Zn_0.4O₈ series thin film by chemical solution deposition method.The interesting phenomenon is that increasing the annealing temperature can be beneficial to increase the grain size,resulting in compactness density.However,the balance of cation pairs(Mn³⁺/Mn⁴⁺,Fe²⁺/Fe³⁺)can be broken by too high annealing temperature.It makes material's electrical property worse.In this thesis,we find,through the heat treatment at 200?of 500 h,the lowest resistance drift rate is only1.02%.?3?We synthesize Mn₂Zn_0.25Ni_0.75O₄ series thin films by RF magnetron sputtering at the various powers.It can be found that sputtering power can affect severely thin film's structure,leading the optical and electrical properties change.Thin film sputtering at 80W has thin thickness that brings about weaker optical absorption and at 200 W has porous structure that gives rise to bad stability.In addition,XPS results confirm that too high or low power can make cations trend higher value states.