光照对LaMnO_3/SrTiO_3中场效应的增强作用

Illumination enhancement on field effect in LaMnO_3/SrTiO_3 surface

钙钛矿镧锰氧化物具有电阻易被光电调控的特性,对以SrTiO_3(STO)为衬底的LaMnO_3(LMO)薄膜在不同外场作用下的电阻和晶体结构的变化规律进行了研究.通过实验发现光电协同作用会增强LMO/STO中的场效应:即在没有光照的情况下,样品的电阻态几乎不随门电压的改变而变化;在有光照的条件下,样品的电阻随会门电压的变化而显著变化.通过X射线衍射(XRD)方法测量STO衬底晶格随光照及门电压的变化规律,发现在光电共同作用下,STO的晶格会显著膨胀,暗示了光电协同作用增强了STO衬底中的铁电极化.根据XRD的结果,本文从微观上解释了LMO/STO异质结中光照对场效应增强的机理.

The applied light and electric field can adjust the resistance of lanthanide manganese oxide thin films under certain conditions.We study resistance and lattice structure properties of LaMnO3（LMO） film,which is grown on a SrTiO3 （STO）substrate and performed diverse properties for different conditions.The film＇s resistance does not change significantly with the applied voltage when it is not illuminated by a laser beam.However,when the film is illuminated by a laser,the resistance varies when the applied gate voltage changes.We use X-ray diffraction （XRD） method to observe STO substrate＇s lattice structure change. We have found that when the electric field is strong enough, light increased oxygen vacancies＇ mobility and enhanced the interface polarization which expands the lattice of STO.