Resonance Raman and photoluminescence investigations were made of {100}<111> penetration twins which formed during homo-epitaxial growth onto (100) substrates via microwave-plasma chemical vapor deposition. A homo-epitaxially grown film which was 0.13mm thick and 1.6mm in diameter was studied using 457.9, 514.5nm and 647.1nm laser excitation. Amorphous C which was incorporated into the twin crystal exhibited resonance Raman enhancement under 647.1nm excitation. Photoluminescence spectroscopy revealed an increased incorporation of N-vacancy and N di-vacancy defects into the twin, as well as a new defect which was not observed in the bulk of the film. The results showed that, when micro-twins had nucleated, they formed a preferential site for the incorporation of amorphous C and other N-based defects.

Y.K.Vohra, A.Israel, S.A.Catledge: Applied Physics Letters, 1997, 71[3], 321-3