Optical evidence for 630-meV phosphorus donor in synthetic diamond

Diamond samples doped with phosphorus either during high-pressure/high-temp erature synthesis or during chemical vapor deposition growth are studied by cathodoluminescence at low temperatures. Some of the specimens unintention ally contain boron accepters in low concentrations as demonstrated by the o bservation of boron-bound exciton emission at 5.215 eV. Other samples show a lower energy-bound exciton line at 5.175 eV relating in intensity to the phosphorus concentration and indicative of a phosphorus impurity or a phosp horus complex. Four samples phosphorus doped by different techniques reveal almost identical discrete donor-acceptor pair-line spectra between 5.2 and 4.7 eV. The appearance of these spectra gives firm evidence for a phosphor us-related donor. Analysis of the spectra assuming boron as the acceptor in volved yields an ionization energy of (630+/-50) meV for the phosphorus don or. [S0163-1829(99)06219-0].