Direct observations of recording marks in the phase-change disk

用透射电子显微镜（TEM）研究了真实的相变盘中Ge_2Sb_2Te_5薄膜的原子结构。用激光辐照沉积的非晶Ge_2Sb_2Te_5薄膜进行初始化（晶化）和记录。横截面TEM观察显示，记录标记被完全非晶化的激光照射。在纳米束电子衍射图和原子对分布函数的强度分布上，观察到了激光辐照诱导的Ge_2Sb_2Te_5非晶样品与沉积态样品之间的细微差别。这种差异是由于非晶态Ge_2Sb_2Te_5的结构弛豫引起的化学有序度的改变。

Atomistic structures of the Ge_2Sb_2Te_5 thin film in the real phase-change disk have been investigated using transmission electron microscopy (TEM). As-deposited amorphous Ge_2Sb_2Te_5 films were laser-irradiated for initialization (crystallization) and recording. Cross-sectional TEM observations revealed that the recording mark was fully amorphized by laser irradiation. A slight difference between the as-deposited and the laser-irradiation-induced amorphous Ge_2Sb_2Te_5 was observed in the intensity profile of nano-beam electron diffraction patterns and atomic pair distribution functions. This difference was attributed to structural relaxation of amorphous Ge_2Sb_2Te_5, which gives rise to the alteration of chemical order.