Characterization of deep defects in boron-doped CVD diamond films using transient photocapacitance method

We have developed a highly-sensitive transient photocapacitance measurement (TPM) system for deep defects in wide bandgap materials, and applied it to characterize the boron-doped diamond films grown on a highpressure/high-temperature-synthesized Ib diamond substrate using high-power-density microwave-plasma chemical vapor deposition method. The developed TPM system has both a low detection limit of less than 0.5 fF for changes in the photocapacitance and a low measurement temperature drift of less than 0.03 K in 12 h. By using the TPM system, we have successfully found an acceptor-type defect around 1.2 eV above the valence band maximum for the B-doped diamond film with a considerably high crystalline quality that had some strong exciton emission peaks in the cathodoluminescence spectra taken at approximate to 80 K. The photoionization cross section and the defect density estimated for the observed defect were 3.1x10(-15) cm(2) and 2.8x10(16) cm(-3), respectively.