利用电化学分析仪对掺铁同成分铌酸锂晶体进行瞬态光电导研究。以不同掺铁浓度铌酸锂晶体为样品，在不同强度的纳秒级脉冲光照射下对光电导的研究发现：铌酸锂晶体的瞬态光电导是由较为复杂的电子迁移过程形成，其衰减可以用一个指数函数叠加一个扩展指数来拟合。拟合参数与光强、掺铁浓度存在以下依赖关系：入射光强增强时，幅值σmax1、σmax2、时间常数τ2和扩展因子β值增大，在光强增大到一定时，τ2和β出现饱和；晶体的掺铁浓度升高时，σmax1、σmax2、τ2值增大，而β值减小。根据实验结果，从理论上提出了光电子导带迁移伴随光电子在小极化子上跳跃迁移的复合电荷传输模型。该模型较好地解释了掺铁同成分铌酸锂晶体的光电导的衰减特点。%Photo-conductivity transient processes of Fe:LiNbO3 congruent crystals are investigated by electro-chemical analyzer. The ex-periments are executed with Fe:LiNbO3 crystals of different Fe concentrations in the conditions of different laser intensities. The results show that the transient photo-conductivity of the Fe-doped lithium niobate crystal is formed through a complex process of electron transport;the decay of photo-conductivity can be fitted to an exponential function and a stretched-exponential function. The dependences of the fitting parameters on laser intensity and iron-doped concentration are measured. The values of amplitudesσmax1 ,σmax2 , time constantτ2 and stretching factorβ increase strongly at low intensities, andτ2 andβ reach their saturation value for higher intensities;with the increase of the concentration of Fe ions, the values ofσmax1 ,σmax2 andτ2 incerease, butβ decreases. With experi-mental results, we propose a charge transfer model which includes the migration of electrons in the conduction band and the jumping of electrons between small-polarons. The model better explains the main features of photo-conductivity decay for Fe-doped congruent lithium niobate crystals.
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