Preparation And Study Of New MgAl₂O₄ Based Oxides

In this paper,MgAl₂O₄(MA12)thin films and F-doped MgAl₂O₄(F-MA12)thin films were prepared by metal oxide deposition(magnetron sputtering)system.Under the condition of oxygen enrichment,the insulation properties of MA12 film and p-type conductivity of F-MA12 film are verified respectively.First of all,by using the orthogonal experimental design method,from the four factors of sputtering power(100 W,200 W,300 W),sputtering pressure(0.4 Pa,0.6 Pa,0.8 Pa),oxygen to argon ratio(5/45,10/40,15/35),substrate temperature(room temperature,100?,200?),we designed the orthogonal experimental table of the three levels of four factors to obtain the optimum process conditions(100 W-0.6 Pa-15/35-100?)for magnetron sputtering.Secondly,in order to verify the theory that MA12 thin film exhibits insulating properties under oxygen rich conditions,MA12 thin films with different oxygen content(30%,40%,50%)were prepared under the process conditions(100 W-0.6 Pa-100?),and annealed at different temperatures(300?,500?,700?,900?).The substrate materials used in the experiment were ordinary glass and P-type(111)single crystal silicon wafers.The effects of the substrate material,heat treatment temperature,and oxygen content on the properties of the MA12 thin film were discussed.The results show that when the oxygen content is up to 40%,the film shows insulation characteristics no matter what heat treatment conditions and substrate materials.When the oxygen content is low,the film shows n-type semiconductor characteristics,and the film deposited on the silicon is more uniform than the glass.Simultaneously,the transmittance of the film under any conditions is above 89%.Furthermore,in order to verify the p-type semiconductor properties of the F-MA12 thin film under oxygen rich conditions,the MA12 thin films with different proportion of F were prepared under the conditions of 100 W,0.6 Pa,100?,20/30,and annealed at different temperatures(300?,500?,700?,900?).The substrate materials used in the experiment were P/N-type(111)monocrystalline silicon,and the effect of material,annealing temperature and F-doped ratio on the film were discussed.By comparing the electrical properties of the films at different temperatures and ratios,it is found that the doping mode of F-MA12 film is affected to some extent by the doping ratio.When the F-doping concentration is small,the doping method is substitution doping,the temperature increases,and internal defects such as grain boundaries are formed in the film.The film has a tendency to crystallize and the film resistance becomes smaller.When the doping concentration is large,such as the MAF1212proportional thin film,the doping method is interstitial doping.The temperature rises from room temperature to 900?.The films remain amorphous,and the Hall coefficient is positive which shows that the film is a P-type semiconductor.Comparing the carrier concentrations of MAF1212,MAF1212-N and MAF1212-glass film,it is concluded that the substrate type affects the stability uniformity of F-MA12 to a certain extent,and the opposite conductivity type substrate has a weakening effect on the electrical properties of the film.At the same time,the transmittances of F-MA12 films are about 89%,belonging to high transmittance material.The results show that the MA12 and the F-MA12 thin films prepared by sputtering and heat treatment have excellent transmittance,and the MA12 thin films and the F-MA12 thin films reflect the insulation characteristics and p-type semiconductor characteristics under certain conditions,which will have a great impact on transparent electronics.