Electron microscopic imaging of an ion beam mixed SiO 2/Si interface correlated with photo- and cathodoluminescence

Abstract

Energy filtered transmission electron microscopy (EFTEM), scanning transmission electron microscopy (STEM) imaging, and electron energy loss spectroscopy (EELS) of a thin 28 nm SiO 2 layer on Si substrate implanted by Si + ions with an energy of 12 keV are reported. The maximum concentration of implanted Si + ions is located near the SiO 2-Si interface region leading there to an ion beam mixed gradual SiO X (2 ≥ x > 0) buffer region, which is even extended into the Si substrate by atomic collisions (knocking-off and knocking-on processes) during ion implantation. Thus, the width of this SiO X buffer layer amounts to about 30 nm extended from 10 to 40 nm depth. The SiO X profile is demonstrated by the above given electron microscopic and spectroscopic methods. Thermal annealing leads to partial phase separation from SiO X1 to SiO X2 with x 2 > x 1 and silicon precipitates (partially nc-Si) changing the photo- (PL) and cathodoluminescence (CL) spectra especially in the near IR-region, probably, due to the formation of Si nanoclusters and associated quantum confinement effects. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.