He注入单晶Si表面形貌的变化研究

沿Si的（100）面注入He离子， 能量为30 keV、 剂量为5×1016 ions/cm2。 注入后样品切成几块， 在真空炉中分别做退火处理， 退火温度从600 ℃到1 000 ℃， 退火时间均为30 min。 利用原子力显微镜研究了各个样品表面形貌的演化。 发现样品表面形貌与退火温度相关联。 假设在气泡中He原子与空位的比值很高， 导致样品内部存在高压的He泡， 从而使样品表面形貌发生变化。 探讨了在Si中He泡随退火温度的演化和He原子在材料中的释放机制及其对表面的影响。

Study of Surface Morphology of Helium Implanted Silicon

P type crystalline Si with (100) orientation was implanted by He ions with energy of 30 keV to a fluence of 5×1016 ions/cm2 . After implantation， pieces of these samples were subjected to thermal annealing at temperatures ranging from 600 ℃ to 1 000 ℃. The microstructures of the annealed sample surfaces were investigated by Atom Force Microscopy (AFM). It was found that the sample surfaces exhibited distinct morphological evolution with annealing temperature. The results were discussed by assuming that the near surface region contains a high ratio of He atoms to vacancies， which lead to the formation of highly pressurized He bubbles and consequently the change of sample surface via bubbles growth and helium release.