Cathodoluminescence and annealing study of plasma-deposited polycrystalline diamond films

Abstract

We have measured the cathodoluminescence spectra of microwave plasma-assisted chemical-vapor deposited (CVD) polycrystalline diamond films at 77 K over the spectral range of 2300–8000 Å. Annealing studies of these spectra have been carried out at 500, 800, 1000, 1200, and 1350 °C. Rich spectra are observed. Many of them are stable up to the highest annealing temperature. Two peaks at 3.188 and 2.638 eV and the 5RL lines are destroyed, while other lines at 3.57 and 3.462 eV appear, after a 1200 °C anneal. The two neighboring peaks at 2.330 and 2.320 eV are probably responsible for the broadness of the often observed peak at 2.328 eV in CVD diamond films. We also compare some of the annealing behavior of the CVD diamond films with those of natural single-crystal diamond, and conclude that while most of the annealing characteristics of plasma-deposited diamond films are similar with those which have been reported for single-crystal natural diamonds, some of the annealing behaviors are different for these two types of materials.