Boron inhomogeneity of HPHT-grown single-crystal diamond substrates: Confocal micro-Raman mapping investigations

Diamond-based rectifiers are promising devices for the development of next-generation power electronics. However, the present device structure limits current operation as low as 5A, which hampers diamond from real industrial applications. One of the critical issues is crystalline defects existing in conducting (low-resistivity) substrates. In this study, we investigated the structural defects of HPHT-grown boron-doped (p+) diamond substrates using Raman mapping. The observed peak shift and broadening of the zone-center peak of diamond occurred owing to the Fano effect caused by heavily boron doping. By considering this effect, the boron uniformity of the p+ diamond substrate is discussed based on the results of peak-shift and full-width-at-half-maximum Raman analysis. The inhomogeneous boron contents were revealed especially at regions where crystalline defects exist. Raman mapping of p+ diamond (100) substrates. [Display omitted] •HPHT-grown boron doped (p+) diamond (100) substrates were structurally investigated by X-ray topography and Raman mapping.•Raman spectra of p+ diamond exhibited downshifted, broadened, and intensity-decreased peak profile due to Fano-effect.•Growth sectors and stacking faults were successfully observed by Raman imaging.•High correlation between dislocation density and Raman peak parameters were revealed.