A cathodoluminescence study of boron doped {111}-homoepitaxial diamond films

In this work we use cathodoluminescence (CL) at liquid helium temperature to investigate the boron incorporation in {111}-homoepitaxial diamond films, grown outside the visible plasma ball by the Microwave plasma-assisted chemical vapor deposition (MPCVD) technique. The boron concentration of this set of films covers the whole possible doping range divided into four parts: Low doping (5 × 1016 < [B] < 1.5 × 1019 cm− 3), high doping (1.5 × 1019 < [B] < 3 × 1020 cm− 3), heavy doping (3 × 1020 < [B] < 2 × 1021 cm− 3), and phase separation range ([B] > 2 × 1021 cm− 3). The phase separation occurs for very high boron concentrations, between the diamond phase (sp3 carbon) and the other components of the layer, namely sp2 carbon and boron. A part of them is accumulated outside the diamond lattice.This detailed cathodoluminescence investigation of {111}-homoepitaxial diamond films has led to determining the doping range of the films and following the evolution of their crystalline quality when the boron concentration increases. In addition, a comparison between {111} and {100} films in the same doping ranges has been undertaken.