Ellipsometric study of F-centres in electron-bombarded KCl

Publisher Website
Google Scholar
Abstract
Bombardment of KCl by electrons with energies in the range of 2-10 keV results in the creation of F-centres to a depth 100-1000 nm. Such centres are identified by a characteristic absorption band centred at a wavelength of 556 nm. The time- and energy-dependence of F-centre absorption have been studied in the past, with some lack of concordance among the results obtained by different observers. Absorption measurements have generally been made in transmission, a matter of some difficulty in weakly absorbing layers of small thickness. It is shown that provided suitable precautions are taken, ellipsometry may be used to obtain consistent, reproducible results. It is established that within close limits. F-centre layers of practically uniform density are produced. The thickness/energy relation obtained in these experiments is found to agree closely with theoretical estimates.