Characterization of Defects in Chemical Vapour Deposited Diamonds

Room-temperature Raman and PL spectra, photocurrent (PC) and thermally stimulated current (TSC) were measured to investigate the mid-gap defects in diamonds grown by using a hot-filament chemical vapour deposition (CVD) technique. The Si-V⁰ centres caused by the Si-C bonds in diamond grains and at grain boundaries are located at 1.68eV. We firstly detect the level 1.55eV by using PL and it is tentatively attributed to the zero-phonon luminescence line or vibronic band of the Si-V⁰ induced by the Si-O bonds. The 2.7-3.2eV and 1.9-2.1eV PC peaks were detected and discussed. The N-V complex may be attributed to these defect levels. Some shallow energy levels lower than 1.0eV were also observed in the CVD diamond.