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利用光子能量为0.12eV的10.6μm连续激光分别辐照了禁带宽度为0.91和0.33eV的光伏碲镉汞探测器.实验表明,激光辐照下禁带宽度为0.91eV的探测器输出正电压,而禁带宽度为0.33eV的探测器对激光的响应方向却与之相反.为了研究此现象,利用功率密度一定的10.6μm激光辐照不同开路电压状态下禁带宽度为0.91eV的探测器,实验结果证实初始开路电压是产生输出电压反向现象的原因.对这一机理进一步分析发现,光伏探测器在光子能量小于禁带宽度的激光辐照下,其开路电压是热激发载流子导致的热生电动势和自由载流子吸收导致的晶格热效应共同决定的.
Photovoltaic HgCdTe detectors with bandgap of 0.91 and 0.33eV were irradiated respectively with 10.6μm continuous laser with photon energy of 0.12eV.The experiments show that the positive output voltage of the detector with the forbidden band width of 0.91eV under laser irradiation , While the detector with a forbidden band width of 0.33 eV responds to the laser in the opposite direction.In order to study this phenomenon, a detector with a forbidden band width of 0.91 eV was irradiated with a laser with a power density of 10.6 μm at different open-circuit voltages The experimental results show that the initial open-circuit voltage is the reason for the reverse of the output voltage.Through further analysis of this mechanism, it is found that the open-circuit voltage of the photovoltaic detector under the laser irradiation with photon energy less than the forbidden band width is the thermal excitation carrier The resultant thermal eigenstates and the lattice thermal effects caused by free carrier absorption are jointly determined.