Mapping of ELNES on a nanometre scale by electron spectroscopic imaging

The amorphous interfacial layer between Si substrates, and diamond films grown by plasma-assisted chemical vapour deposition has been studied by electron spectroscopic imaging. The amorphous layer consists mainly of carbon, which can only be distinguished from the diamond film by analysis of the near-edge structure (ELNES) of the carbon K edge. Series of electron spectroscopic images were acquired across the carbon K edge and were analysed in order to reveal the presence of the pi*- and sigma*-excitations. After background removal from the corresponding images, phase maps for the distribution of sp(2) and sp(3) hybridized carbon can be obtained. From the whole series of images, electron, energy-loss spectra can be extracted for any given area in the images. The results show that the amorphous layer covers large areas along the interface and that regions with only 1-2 nm layer thickness can clearly be analysed. The results obtained with the electron spectroscopic imaging technique will be compared with results obtained on a field emission gun scanning transmission electron microscope. .