Surface Erosion of GaN Bombarded by Highly Charged ²⁰⁸Pb^q+-Ions

Surface change of gallium nitride specimens after bombardment by highly charged Pb^q+-ions (q=25, 35) at room temperature is studied by means of atomic force microscopy. The experimental results reveal that the surface of GaN specimens is significantly etched and erased. An unambiguous step-up is observed. The erosion depth not only strongly depends on the charge state of ions, but also is related to the incident angle of Pb^q+-ions and the ion dose. The erosion depth of the specimens in 60°incidence (tilted incidence) is significantly deeper than that of the normal incidence. The erosion behaviour of specimens has little dependence on the kinetic energy of ion (E_k=360, 700keV). On the other hand, surface roughness of the irradiated area is obviously decreased due to erosion compared with the un-irradiated area. A flat terrace is formed.