Origin of band-A emission in homoepitaxial diamond films

Origin of the band-A emission of diamond was investigated to use homoepitax ial diamond films by means of scanning cathodoluminescence (CL) using field emission scanning electron microscopy and high-resolution transmission ele ctron microscopy (HRTEM). It was revealed that the band-A emission localize d only inside of the non-epitaxial crystallites (unepitaxial crystallites o r UCs), and grain boundaries and dislocations around the emission sire of t he band-A were also localized in the UC sites: cross-sectional CL revealed in sub-micron scale that some parts in an UC showed the band-A emission, an d HRTEM revealed that there were the same structures of grain boundaries as those had pi* states determined by electron energy loss spectroscopy (EELS ), where pi* states correspond to sp(2) states of defects in diamond. These experimental results indicate that one of the origins of the band-A emissi on is attributed to sp(2) states of defects in diamond located in grain bou ndaries and/or dislocations. (C) 2001 Elsevier Science B.V. All rights rese rved.