Mechanism of damage buildup in ion bombarded ZnO

Ion beam induced defect processes in wide bandgap compound semiconductors are rather complex because of the formation of different types of defects and their transformations. In this paper, we report results of the study on the mechanism of defect formation, migration and agglomeration in 300 keV Ar-ion bombarded ZnO single crystals. RBS/c analysis performed with the use of the unique McChasy code allowed determination of depth distributions for different defect types separately. Complementary HRXRD analysis was applied to study lattice deformation due to ion bombardment. It has been observed that migration of simple defects and their agglomeration lead to the formation of two types of dislocation loops: basal loops located at the depth corresponding to the range of incident Ar ions and prismatic loops located beyond the ion range. The stress induced by defects in the bombarded layer has been identified as the driving force for defect migration and loop formation. As soon as the critical stress is attained bombarded layer undergoes plastic deformation resulting in the formation of a dense dislocation tangle.

336