The rectifying property and photovoltaic effect in the La ₀.8Ag_0.2MnO₃/SrTiO_3-Nb heterojunction

A p - n junction composed of Ag⁺-doped manganite La _0.8Ag_0.2MnO₃(LAMO) and Nb-0.5wt%-doped SrTiO₃(STON) was fabricated using the pulsed laser deposition method. The heterojunction exhibits a good rectifying property over a wide temperature range from 20 to 390 K. The minimum diffusion potential and the lowest leakage currents under different negative voltages both occur at 320 K, which is around the metallic-insulator transition temperature of the LAMO film. The photovoltage rises with the decreasing temperature and wavelength of the laser beam. Under the illumination of a 473 nm laser beam, the photovoltage grows as the light power increases and seems to be saturated at about 300 mW. The maximum V _oc is 0.76 V, which is close to the diffusion voltage.