Effect of oxygen vacancy gradient on ion-irradiated Ca-doped YMnO3 thin films

Abstract

In this study, we investigate the effect of ion irradiation on Y0.95Ca0.05MnO3 (YCMO) thin films. X-ray diffraction and Raman spectroscopy measurements show single-phase and strain/stress modifications with ion irradiation. Rutherford backscattering spectrometry confirms the variation in oxygen vacancies. The near-edge x-ray absorption fine structure shows valence state reduction of Mn ions, which is attributed to oxygen vacancies. The optimal resistive switching ratio is observed at the lowest fluence (1x10(11)ions/cm(2)) of ion irradiation. At higher fluences (1x10(12) and 1x10(13)ions/cm(2)), the strain relaxation and oxygen vacancy annihilation are ascribed to the local annealing effect. The double logarithmic curve and modified Langmuir-Child's law satisfy the space charge limited conduction mechanism in all thin films. These results suggest the crucial role of irradiation-induced oxygen vacancies in modifying the electronic structure and electrical properties of YCMO thin films.