Application of spatially resolved electron energy-loss spectroscopy to the quantitative analysis of semiconducting layer structures

摘要

We investigate the potential of spatially resolved electron energy-loss spcetroscopy for obtaining quantitative information on the profile of semiconducting layer structures.Operating a transmission electron microscope with an attached imaging filter in the line focus mode and orienting the layer structure accurately parallel to the energy-dispersive direction,we record spectrum images with a space co-ordinate (the growth direction) as a function of the energy loss.We present two practical examples:1.Using Ge and Si core losses,quantitiative chemical profiles across a SiGe/Si quantum well structure are obatined.2. Recording spectrum images with high dispersions,we study the near-surface region of an oxidised and carbon-capped SiGe layer in cross-section.The fine structure of amorphous SiO_2.From the experimental data we estimate the accuracy of elemental mapping of SiGe by energy-selected imaging and the detectability of thin layers of C and SiO_2 in Si(Ge) by spcetrum imaging.