Ge2Sb2Te5非晶薄膜中超快载流子动力学的飞秒分辨反射光谱研究

利用飞秒时间分辨抽运-探测反射光谱技术研究了室温下Ge₂Sb₂Te₅非晶薄膜中载流子超快动力学及其激发能量密度依赖性.发现光激发后05 ps时间内，反射变化率降到最小值，然后开始迅速增加，在几个皮秒时间内达到大于初始反射率的新的最大值.反射率的减小量、增加量和增加速率均随激发能量密度的增大而增加.利用高密度等离子体的Auger复合及其感应的晶格加热模型较好地定量解释了反射率由最小到最大的快速变化过程，表明高密度等离子体的Auger复合加热 关键词： 抽运-探测光谱 2Sb₂Te₅非晶薄膜')" href="#">Ge₂Sb₂Te₅非晶薄膜 Auger复合 载流子动力学

Study of ultrafast carrier dynamics in amorphous Ge2Sb2Te5 film by femtosecond-resolved reflectivity spectroscopy

Ultrafast dynamics and its excitation-energy-density dependence of photoexcited carriers in amorphous Ge₂Sb₂Te₅ film were studied at room temperature by femtosecond-time-resolved pump-probe reflectivity spectroscopy. It was found that the reflectivity reduced down to a minimum in 05 ps after pump excitation, and then started to increase sharply up to a new maximum value larger than the initial reflectivity in several picoseconds. Furthermore, the decreased and increased amplitudes of the reflectivity with respect to its initial value as well as its rising rate from the minimum to the maximum both increased with the increasing excitation energy density. The sharp rising process of the reflectivity was explained quantitatively based on the model of Auger recombination of high density plasma and Auger-recombination-induced heating of cyrstal lattice, which shows that the heating effect induced by Auger recombination in high density plasma should be the main mechanism of ultra-short laser pulse-induced phase change.