Toward large area conductive single crystal diamond: linear antenna MW PECVD of doped diamond layers on heteroepitaxy diamond substrates

This study describes the successful growth of highly boron-doped epitaxial diamond layers on heteroepitaxy diamond substrates using linear antenna microwave plasma CVD technology. Detailed characterisation by X-ray and electron diffraction confirms that the grown boron-doped diamond layers sustain epitaxy, while Raman and van de Pauw characterisation confirms high B incorporation and electrical performance with single crystal diamond characteristics. Electrochemical investigation demonstrates that the boron-doped diamond layers function as high-quality electrodes, offering a scalable route toward producing wafer-scale single crystal diamond devices. By overcoming the size limitations of traditional single crystal diamond and limits in cavity-based microwave plasma CVD technology, the combination of scalable heteroepitaxy diamond substrates with large area linear antenna microwave plasma CVD could provide a bridge toward future applications. Novelty statement: In this work we report the growth of highly boron-doped epitaxial diamond layers on heteroepitaxy diamond substrates using linear antenna MW PECVD. Characterisation of samples confirms high boron incorporation with Hall mobility values higher than that expected for polycrystalline diamond. Epitaxy in the grown layer is confirmed by bulk (X-ray) and localised (electron) diffraction. Finally, the suitability of the grown layers for electrodes in electrochemistry is investigated and confirmed.