Dislocations in chemical vapor deposition diamond layer detected by confocal Raman imaging

Abstract

Dislocations in a homoepitaxial diamond film grown by chemical vapor deposition (CVD) were characterized by confocal Raman imaging. The diamond film was grown on a high-pressure high-temperature (HPHT) substrate using an oxygen-adding condition to minimize dislocation formation during diamond growth. The dislocation densities in the CVD thin film and substrate were found to be 3 × 104 and 2 × 104 cm−2, respectively, from large-area Raman imaging. The spatial variation of stress around dislocations in CVD diamond was analyzed three-dimensionally using in-plane images of peak positions of diamond first-order lines taken at different depths from the diamond film surface. The variational directions of the stresses depended on the types of dislocation: ⟨110⟩ variational direction corresponds to edge [001] dislocation, whereas the ⟨100⟩ variational direction corresponds to 45° mixed [001] dislocation. Most dislocations passed through the CVD thin film from the substrate. Some dislocations were newly generated at the CVD layer–substrate interface. The dislocations in CVD diamond propagate along the [001] direction of diamond crystal with the same Burgers vector in the HPHT substrate.