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实验研究了具有pn结结构的碲镉汞光电二极管的双光子吸收.激发光源采用了皮秒红外脉冲激光.尽管入射光子能量仅为碲镉汞材料带隙的60%左右,在光电二极管两电极端仍然观察到了显著的光伏响应信号.利用线性关系拟合双对数坐标系下光伏响应与入射光强的关系,发现两者呈现二次幂函数增强趋势,表明这种光伏响应是一种典型的双光子吸收过程.通过调节光电二极管两端的反向偏压,空间电荷区内的双光子吸收系数可比耗尽层外的强致130倍,这种双光子吸收系数的场致增强现象可归因为双光子吸收的FK效应所致.对比空间电荷区内外双光子吸收产生的光生载流子数量,证实空间电荷区内的双光子吸收会强烈地影响器件的光伏响应.
The two-photon absorption of a CdTe photodiode with a pn junction structure was experimentally studied, and the picosecond infrared pulsed laser was used as the excitation light source. Although the incident photon energy is only about 60% of the bandgap of the HgCdTe material, At the extreme, a significant PV response signal was still observed. Using the linear relationship to fit the relationship between the PV response and the incident light intensity in the double logarithmic coordinate system, it was found that the two exhibited a second power function enhancement trend, indicating that this photovoltaic response is a typical By adjusting the reverse bias voltage across the photodiode, the two-photon absorption coefficient in the space charge region can be 130 times stronger than that outside the depletion layer. The field enhancement of this two-photon absorption coefficient can be attributed Due to the FK effect of two-photon absorption, comparing the number of photo-generated carriers generated by two-photon absorption inside and outside the space charge region confirms that the two-photon absorption in the space charge region strongly influences the photovoltaic response of the device.