Excitonic recombinations and energy levels of highly boron doped homoepitaxial diamond films before and after hydrogenation

The incorporation of ≈1019 B-cm−3 has several effects in the cathodoluminescence spectra of homoepitaxial MPCVD film: (1) the TO free exciton and all the boron-bound excitons' peaks broaden and shift downward in energy (“electronic” effect). Plasma post-hydrogenation (P-H) destroys all of them. (2) It induces a low concentration of several species of defects (“structural” effect): (i) a broad band around 4.99 eV with a shoulder around 4.86 eV, small bands on a broad 4.68 eV band, peaks and bands between 2.9 and 4.5 eV, the “2.8 eV” A band. They originate from B-induced species of defects only existing when [B]≥≈1019 cm−3. Most of them disappear after P-H. (ii) broad bands around 3.65, 4.1 and 4.68 eV. They originate from B-induced species of defects already existing when [B]<1017 cm−3. P-H prevents the formation of free exciton, doesn't induce any new defect giving radiative recombination above 2.6 eV, heals some structural defects of diamond.