Diamond dislocations analysis by X-ray topography

Abstract

The dislocation identification method using X-ray topography by reflection mode geometry was applied to characterize IIa, Ib and highly B doped high pressure high temperature (HPHT) grown crystals. In both IIa and Ib crystals, dislocations are found to propagate in the <111> grown direction, with dominant vectors of [110] and [1-10], neither of which has no c-axis segment. For Ib crystal, many dislocations are also generated in the <112> and <121> directions, which are slightly tilted to <111>. It was confirmed that the dislocations in the same direction have the same Burgers vectors, but the dislocations are spread in broad area. A total of up to 20 HPHT crystals were measured and found to exhibit different dislocation distributions. This indicates an immature growth technique in terms of dislocation. Measurements of four chemical vapor deposition (CVD) substrates showed numerous dislocation bundles, making individual dislocation directions analysis impossible. CVD substrates suffer from an increase in dislocations due to CVD growth, resulting in poor diamond quality in terms of dislocation. XRT analysis on dislocations of epitaxial growth will be very important prior to CVD substrates analysis.