非晶N:GeSb薄膜的光致晶化及其相干声子谱表征

Femtosecond Laser-irradiated Crystallization of Amorphous N: GeSb Film and Its in-Situ Characterization by Coherent Phonon Spectroscopy

利用对微结构变化非常灵敏的相干声子光谱技术研究了非晶N:GeSb薄膜的光致相变特征。发现当激光辐照能流达到某个阈值时,出现了一个新的声子模,表明相变的发生。同时,退火晶化的N:GeSb薄膜也出现此新的声子模,表明激光照射的确导致了薄膜的晶化。相干光学声子谱的抽运能量密度依赖实验结果表明光致晶化的N:GeSb薄膜的相干光学声子的寿命和频率均随抽运能量密度增加而减小,与晶体中的依赖关系一致。结果表明N:GeSb薄膜的光致晶化质量较好,具有相变光存储应用潜力。

Laser irradiation induced phase change of a new amorphous N：GeSb film is studied by coher-ent phonon spectroscopy,which is very sensitive to its microstructure.It is found that a new coherent op-tical phonon （COP）occurs as laser irradiation fluence reaches some threshold,implying laser-induced phase change emerged.Meanwhile,this new phonon also occurs in annealed crystallized N：GeSb film, which proves that the laser irradiation does lead to the crystallization of the N：GeSb film.Pump fluence dependence of COP dynamics of laser-induced crystallized N：GeSb film shows that the frequency and life time of COP decrease as pump energy density increases,which is in accordance with the annealed crys-tallized N：GeSb film.So it implies the high crystalline quality of the laser-induced phase-change film and the potential application of N：GeSb films in optical phase change memory.