Time response of photovoltage in La0.9Li0.1MnO3/SrTiO3–Nb heterojunction under ultraviolet light

We focus on the time response of photovoltage property in heterojunction composed of univalent doped manganite La0.9Li0.1MnO3(LIMO) and SrTiO3–Nb(STON). Under the irradiation of 248 nm laser pulse, the photovoltage shows a second order exponential rising process with time constants τ1(=27.7–93.0 μs) and τ2 (<9.84 μs). After the light source is shut down, the photovoltage exhibits a first order exponential decreasing stage. The carrier lifetime τ at the order of millisecond in this p–n junction is much longer than that in similar p–n junctions based on manganites. The maximum values of both τ1 and τ appear at around 250 K, which coincides with the metallic-insulator transition temperature for LIMO. These imply that the time response property of heterojunction is partly controlled by the inherent transportation mechanisms in the LIMO layer.