Defect and Threading Dislocations in Single Crystal Diamond: A Focus on Boron and Nitrogen Codoping

Abstract

For the fabrication of vertical power electronic components, the use of a freestanding highly boron‐doped single crystal diamond substrate is mandatory, on top of which a thin low‐doped active layer is overgrown. The crystalline quality of this substrate is of prime importance as the high doping level required is also likely to lead to the generation of extended defects in the active layer. Herein, the improvement of the quality of thick highly boron‐doped diamond films grown by chemical vapor deposition (CVD) is investigated. Codoping with a low amount of nitrogen is explored as a way to limit the formation and propagation of extended defects. It is shown that the growth rate and boron concentration are not impacted by the addition of nitrogen with the parameters used in this study. Surface morphology and defect density estimated for each amount of nitrogen are presented; and Raman spectroscopy confirms that nitrogen addition compensates the strain induced by boron incorporation in single crystal diamond. Codoping with nitrogen is thus demonstrated as a useful strategy to obtain high quality boron‐doped diamond substrates potentially suitable for the development of power devices.