High crystalline quality single crystal chemical vapour deposition diamond

Abstract

Homoepitaxial chemical vapour deposition (CVD) on high pressure, high temperature(HPHT) synthetic diamond substrates allows the production of diamond material withcontrolled point defect content. In order to minimize the extended defect content, however,it is necessary to minimize the number of substrate extended defects that reach the initialgrowth surface and the nucleation of dislocations at the interface between the CVD layerand its substrate. X-ray topography has indicated that when type IIa HPHT syntheticsubstrates are used, the density of dislocations nucleating at the interface can be less than 400 cm−2. X-ray topography, photoluminescence imaging and birefringence microscopy of HPHT grownsynthetic type IIa diamond clearly show that the extended defect content is growth sector dependent.⟨111⟩ sectors contain the highest concentration of both stacking faults and dislocations but⟨100⟩ sectors are relatively free of both. It has been shown that HPHT treatment of such materialcan significantly reduce the area of stacking faults and cause dislocations to move. Thisknowledge, coupled with an understanding of how growth sectors develop during HPHTsynthesis, has been used to guide selection and processing of substrates suitable for CVDsynthesis of material with high crystalline perfection and controlled point defectcontent.