New Compositionally-Ordered GeSi Nano Dots Fabricated with 1250 keV Electrons

Abstract

Transformation of uniformly strained GexSi1-x layers into GeSi dots of 3 ~ 7 nm which are compositionally ordered by one or concurrently two sets of {111} planes was carried out for the first time under non-equilibrium conditions induced by 1.25 MeV electron irradiation at Tc ≥ 200 oC in the high voltage electron microscope (JEM-ARM1300S). This microscope installed in the KBSI is characterized by an excellent point-to-point resolution of 0.12 nm allowing obtaining detailed information on chemical ordering at specific parameters of defocus (-800 Å) and crystal thickness (200~250 Å) determined by extensive HRTEM image simulation for the ordered dots.