Electronic properties of defects created in epitaxially grown n-Si by iow energy He and Ar ions

Ion beam etching with noble gases is routinely used in the fabrication of submicron-scale structures. Low energy ion bombardment, however, introduces near surface defects in semiconductors, which may alter their electrical properties, and may hence govern the properties of devices fabricated on these semiconductors. We have employed deep level transient spectroscopy (DLTS) to characterise the defects induced by low energy (1 keV) He- and Ar-ion bombardment of epitaxially grown n-type Si, each of which introduced several prominent electron traps. We found that the DLTS spectrum of low energy Ar-ion bombarded Si contained a number of peaks that that were not present in the low energy He-ion bombarded sample. The DLTS spectra of both low-energy bombarded samples displayed several peaks in addition to the V ₂, VO and VP centres which are generally observed in the spectrum obtained from high energy (5.4 MeV) α-particle implanted Si. We attribute the differences in the defects induced by low energy He and Ar ions and high energy He ions to their different stopping powers, i.e. the different rate of energy loss in Si, as well as the inclusion of He and Ar ions in vacancy complexes.