Identification of nitrogen decorated vacancies in CVD diamond films using positron annihilation coincidenceDoppier broadening spectroscopy

摘要

Coincidence Doppier broadening studies (CDB) have been carried out on CVD diamond films. The coincidence Doppler broadened spectra are analyzed to obtain information about the chemical surroundings at the annihilation site. Remarkably large fraction of positrons are seen to annihilate with the nitrogen present as impurity in low concentration. Complementary positron lifetime (LTS) measurements indicate Saturation trapping of positrons, primarily in monovacancies and vacancy clusters. The information obtained from CDB and LTS studies provides direct observation of nitrogen decorated vacancies or nitrogen vacancy complexes in diamond film. Our results highlight the Potential of CDB technique in characterizing impurity precipitates and impurity vacancy complexes in diamond.