脉冲激光烧蚀制备四方结构的橄榄球状Ge纳米颗粒

Synthesis of Rugby-Ball Like Germanium Nanocrystals with Tetragonal Structure by Pulsed Laser Ablation

采用KrF脉冲准分子激光器烧蚀金刚石结构多晶Ge靶材,选取合适的靶与衬底间的距离、氩气压力以及沉积时间,在单晶Si(100)衬底上首次制备了四方结构的Ge纳米颗粒,扫描电子显微镜表征显示这些Ge纳米颗粒有橄榄球状的外形。透射电子显微镜和选区电子衍射结果显示,这些橄榄球状的Ge纳米颗粒是四方结构的单晶。而这些Ge纳米颗粒的形成是由于脉冲激光击打Ge靶产生的小的团簇在局域高温的作用下生成四方结构的团簇,而这些四方结构的团簇和Ar气原子发生碰撞并聚集到一起形成橄榄球状Ge纳米颗粒。

Germanium nanocrystals （Ge-Ncs） were well synthesized by using a KrF excimer laser ablation to ablate polycrystalline Ge target with diamond structure. The rugby-like Ge nanocrystals with tetragonal structure were synthesized on Si （100） substrate by adjusting target-substrate distance, Ar pressure and ablating time. Scanning electron microscopy showed that these Ge-NCs had a rugby-ball like shape; transmission electron microscopy and selected area electron diffraction showed that the single-crystal state synthesized Ge-NCs were of tetragonal structure. Some small clusters were generated when pulse laser ablated the target and the tetragonal structure was formed due to the local high temperature and pressure. These small clusters with tetragonal structure aggregated to form rugby-ball like nanocrystals due to the collision with Ar gas atoms.