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采用波长均为532 nm的连续激光和脉冲激光研究了缺氧La0.6Ca0.4MnO3-δ(LCMO)薄膜的光响应特性。分析了在金属态和绝缘态时,缺氧对LCMO薄膜光响应的不同影响。在脉冲宽度7 ns、峰值功率750 mW的脉冲激光作用下,缺氧LCMO薄膜在室温下呈现出明显的光响应信号,其光电导增大36.4%,上升时间约30 ns。由于光子能量大于LCMO的禁带宽度,光子注入在薄膜中产生了电子-空穴对,而电子很容易被氧空位俘获,从而在薄膜中产生大量额外的空穴载流子,大量的空穴载流子可能诱发局域绝缘-金属相变,从而在薄膜中产生明显的光电导效应。实验显示出缺氧钙钛矿薄膜在光电器件上的巨大应用潜力。
The photoresponse characteristics of an anoxic La0.6Ca0.4MnO3-δ (LCMO) thin film were investigated by continuous laser and pulsed laser at 532 nm. The different effects of anoxia on the photoresponse of LCMO films were analyzed in the metallic and insulating states. The hypoxic LCMO thin film shows obvious photoresponse signal at room temperature under pulsed laser with a pulse width of 7 ns and a peak power of 750 mW. The photoconductivity increases by 36.4% and the rise time is about 30 ns. Since the photon energy is greater than the forbidden band width of the LCMO, photon injection creates electron-hole pairs in the film and the electrons are easily trapped by the oxygen vacancies resulting in a large amount of extra hole carriers in the film, a large amount of holes The carriers may induce local insulation-metal phase transitions, resulting in significant photoconductivity in the film. Experiments show that the anoxic perovskite film has great potential in optoelectronic devices.