Preparation And Electromagnetic Property Research Of Si Based LSMO Thin Films And Heterojunctions

Perovskite oxide thin films have attracted great interest for their potential and wide applications. Since the La1-xSrxMnO3(LSMO) films exhibit the excellent electromagnetic properties and colossal magnetoresistance effect, they have wide potential applications in the field of information technique.La0.7Sr0.3MnO3 thin films was deposited by magnetron sputtering in the intrinsic Si(100) and doped n-type Si(100). The effect of the deposition temperature,annealing and magnetic field on La0.7Sr0.3MnO3 thin films electromagnetic characteristics were analied.And the effect of the atmosphere, temperature and magnetic field on rectifying characteristics of La0.7Sr0.3MnO3/Si p-n junction were analied.The films were studied by ellipsometer,XRD and SEM. The conclusions as follows:(1)Different substrate temperature, annealing temperature and magnetic field, different metal-insulator phase transition temperature. With annealing oxygen content in the film, its Curie temperature will rise.In the same time, there is a marked rise in temperature coefficient of resistance.(2)When the current increases,the metal-insulator transition temperature TMI of La0.7Sr0.3MnO3 film will gradually move to the low temperature, Resistance peak continuously decreased.It is confirmed that there is tunneling effect in the smaller thickness grain boundaries of the film.(3)Different atmosphere and annealing, La0.7Sr0.3MnO3/Si p-n junctions have different electric properties.Under Ar and O2,the sample have the better electric properties than others; Annealing can improve the rectifying characteristics and annealing time can affect the rectifying characteristics.The sample annealed by 10min have the best rectifying characteristics.(4)La0.7Sr0.3MnO3/Si heterostructure exhibit good rectifying characteristic in a wide temperature range from 80K to 300K.And when temperature is higher, rectifying characteristics are better.Large magnetoresistance up to 60% was observed in a low field of 0.3T in these junctions. Magnetoresistance depend on temperature(T).When T>Tc,MR<0 and when T0.The junction magnetoresistance depends on current and bias.