Recovery treatments for ion-induced defects in high-quality homoepitaxial CVD diamond

Effects of vacuum annealing and hydrogen plasma exposure on ion-implantation-induced defects have been investigated in case of high-quality chemical-vapor deposited (CVD) diamond mainly using cathodoluminescence (CL) measurements. The well-focused 30-keV Ga ions were implanted into regions with different ion doses from 1 x 10(12) to 1 x 10(15) ions/cm(2). The free-exciton emission and the N-V center were observed at 235 and 575 nm, respectively, in room temperature CL spectra for as-gown homoepitaxial CVD diamond. The former vanished completely after all the implantation processes examined while the latter was destroyed more strongly with increasing ion doses. On one hand, the band edge emissions at 235 nm were hardly recovered even after any treatments examined. On the other hand, the CL peak at 575 nm reappeared either after a 30-min vacuum annealing at 900 degreesC for the Ga dose of 1 x 10(12) ions/cm(2) or after a suitable hydrogen plasma treatment for all the Ga ion dosages examined. Thus, it is found that the band edge emission signal is required to investigate the beam damages to 'high' crystalline quality diamond. A removal of the damaged surface layer by the plasma etching is also discussed in relation to the recovery process mainly for the 575-nm peak at heavier ion doses. (C) 2001 Elsevier Science B.V. All rights reserved.