锰掺杂近化学计量比铌酸锂晶体的电荷输运过程

用泵浦(350 nm)-探测(780 nm)法研究了轻度锰掺杂近化学计量比铌酸锂晶体的光致吸收的特征,结果表明光致吸收的暗衰减过程以扩展指数的形式衰减,并测量了饱和光致吸收、衰减时间常量和扩展因子对泵浦光光强的依赖关系.在z轴方向上加直流电场测量了紫外光照射下光伏打电流强度和光电导,发现它们与光强之间成超线性关系.实验结果可以用考虑本征缺陷能级和掺杂能级之间激发和复合的修正的双中心电荷输运模型进行定量的解释.

Charge Transport Process in Mn-doped Stoichiometric Lithium Niobate

Light-induced absorption was investigated by the pump-probe (350 nm and 780 nm) method in near-stoichiometric LiNbO_3 crystals slightly doped with Mn. It was shown that the dark decay process of light-induced absorption exhibits a stretched-exponential behavior, and the dependences of the saturated light-induced absorption, the decay time constant,and the stretching factor on the pumping intensity were presented. The photovoltaic current intensity and the photoconductivity under UV illumination were measured by applying a DC field along the z-axis of the sample. The photoconductivity and the photovoltaic current density showed superlinear dependence on intensity. The experimental results can be explained quantitatively by developing the two-center charge transport model with direct excitation and recombination between dopants and internal defects.