Chemical-state-selective observations on Si-SiOx at nanometer scale by photoelectron emission microscopy combined with synchrotron radiation

Abstract

Photoelectron emission microscopy (PEEM) excited by soft X-rays from synchrotron light source has been applied to observations on chemical-state-selective images at nanometer scale for micro-patterned silicon oxides on silicon. The micro-patterns of silicon oxides were prepared by O2+ ion implantation in Si(001) using a mask of 12.5 μm periodicity. By tuning the energy of X-rays, we have observed nano-scaled images of Si-SiOx micro-pattern depending only on the valence states of silicon. The interfaces between Si and SiO2 became dim upon heating, but only Si (Si0) and SiO2 (Si4+) were seen. It was elucidated that the annealing induces the hopping of Si valence states from Si0 to Si4+ without taking any intermediate valence states such as Si2+ and Si3+.