【摘要】 采用时间分辨抽运-探测透射光谱,研究了不同波长和不同激发流密度下半金属Sb薄膜的超快电子动力学过程.透射变化率的时间延迟扫描曲线显示在延迟零点附近出现强的振荡,正的吸收饱和峰在亚皮秒时间内衰减为负的吸收增强峰.之后,负的吸收增强峰在数皮秒时间内甚至再次演变为吸收饱和.正饱和峰和负吸收峰幅度正比于激发流密度和光波长.对这些现象进行了分析,引入"缺陷"态模型及考虑"缺陷"态对光激发电子的快速俘获和逐渐释放,能够合理、半定量地解释实验观察到的所有现象.更多还原

【Abstract】 The time resolved pump-probe spectroscopy was used to study the ultrafast carrier dynamics of semimetal Sb films at different wavelengths and pump fluences.The profiles of differential transmission versus delayed time showed sharp oscillation near the zero-time-delayed point.A positive absorption saturation peak turned into a negative absorption peak in subpicosecond time.Then the latter began to attenuate and again showed absorption saturation eventually in several picoseconds.The amplitudes of the positive and negative peaks were proportional to the pump fluence and wavelength.These phenomena are analyzed in this article and explained reasonably and semi-quantitatively by introducing the "defect model" and considering fast capture and release by "defect states" of hot electrons.更多还原