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 5 A, 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. (C) 2015 Elsevier B.V. All rights reserved.