高电荷态离子$lt;sup$gt;126$lt;/sup$gt;Xe$lt;sup$gt;$lt;i$gt;q$lt;/i$gt;+$lt;/sup$gt;引起GaN表面形貌变化研究

用不同电荷态的¹²⁶Xe^q+离子（9≤q≤30）在室温下轰击GaN晶体表面，经原子力显微镜分析表明，当q>18，辐照区域由隆起转为显著的刻蚀.被轰击后的GaN晶体表面形貌主要取决于入射离子的电荷态.同时，样品表面形貌还与入射离子的剂量和入射角有关；在实验参数范围，与入射离子的初动能没有明显关系（180 keV≤E_k≤600 keV）.当入射离子的电荷态q=18，与样品表面法线成60°角倾斜入射和垂直表面入射时，样品的表面几乎没有变化，只是倾斜入射后有很微小的隆起；当q＜18时，样品表面膨胀隆起，粗糙度增强，倾斜入射时表面隆起比垂直入射时更明显，而且都有清晰的峰状分界区；当q＞18时，样品表面被蚀刻呈凹陷状，有明显的齿状刻痕，且侵蚀深度与离子剂量近似呈线性关系，倾斜入射时的刻蚀深度大于垂直入射时的刻蚀深度.关键词：高电荷态离子GaN晶体原子力显微镜表面形貌

Surface morphology of GaN bombarded by highly charged 126Xeq+ ions

N-type GaN films bombarded with different highly charged ¹²⁶Xe^q+-ions（9≤q≤30） at room temperature was studied by atomic force microscopy. The experimental results show that when q exceeds the threshold value 18, remarkable swelling turns into obvious erosion in the irradiated area. On the other hand, surface disorder of GaN films strongly depends on the charge state q of ions, incident angle and ion influence, and the damage behavior of films is unrelated to the kinetic energy within the scope of experimental parameters（180 keV≤E_k≤600 keV）.For q=18, the surface morphology of the films almost does hot change at normal incidence, and at incidence angle of 30° relative to the film surface, there appears small-scale swelling in irradiated region and a low step forms between the irradiated and un-irradiated regions. For q<18, the film surface is capped with an amorphous layer, with increased roughness, distinct swelling. Moreover, especially at and near the boundaries, a series of remarkable sharp bumps like ridges are observed. And an evident step-up is formed between the irradiated and un-irradiated regions. The step is more remarkable for tilted incidence than normal incidence. For q>18, film surface is etched, forming a deep dump with a high step with the increase of ions influence. Unambiguous indentations relevant to the ion influence on the step appear. Furthermore, the step height is proportional to the ion influence approximately and is much higher for tilted incidence than normal incidence.