低速高电荷态重离子辐照的GaN晶体表面X射线光电子能谱研究

X-ray photoelectron spectroscopy study on GaN crystal irradiated by slow highly charged ions

利用低速高电荷态Xeq+和Pbq+离子对在蓝宝石衬底上生长的GaN晶体膜样品进行辐照,并利用X射线光电子能谱(XPS)对样品表面化学组成和元素化合态进行了分析.结果表明,高电荷态离子对样品表面有显著的刻蚀作用;经高电荷态离子辐照的GaN样品表面氮元素贫乏而镓元素富集;随着入射离子剂量和所携带电荷数的增大,Ga—Ga键相对含量增大;辐照后,GaN样品中Ga—Ga键对应的Ga3d5/2电子的束缚能偏小,晶格损伤使内层轨道电子束缚能向低端方向偏移.

We utilize slow highly charged ions of Xeq ＋ and Pbq ＋ to irradiate GaN crystal films grown on sapphire substrate,and use X-ray photoelectron spectroscopy to analyze its surface chemical composition and chemical state of the elements.The results show that highly charged ions can etch the sample surface obviously,and the GaN sample irradiated by highly charged ions has N depletion or is Ga rich on its surface.Besides,the relative content of Ga—Ga bond increases as the dose and charge state of the incident ions increase.In addition,the binding energy of Ga 3d5/2 electrons corresponding to Ga—Ga bond of the irradiated GaN sample is smaller compared with that of the Ga bulk material.This can be attributed to the lattice damage,which shifts the binding energy of inner orbital electrons to the lower end.