Positive secondary Ion emission from Si 1− xGe x bombarded by O 2+

Abstract

The positive secondary ion yields of B + (dopant), Si + and Ge + were measured for Si 1− x Ge x (0 ≤ x ≤ 1) sputtered by 5.5 keV 16O 2 + and 18O 2 +. It is found that the useful yields of Ge + and B + suddenly drop by one order of magnitude by varying the elemental composition x from 0.9 to 1 (pure Ge). In order to clarify the role of oxygen located near surface regions, we determined the depth profiles of 18O by nuclear resonant reaction analysis (NRA: 18O(p,α) 15N) and medium energy ion scattering (MEIS) spectrometry. Based on the useful yields of B +, Si + and Ge + dependent on x together with the elemental depth profiles determined by NRA and MEIS, we propose a probable surface structure formed by 5.5 keV O 2 + irradiation.