Recent Progress of Boron Doping in Diamond by Ion Implantation

Abstract Ion implantation in diamond has long been explored, but many challenges remain before it can be fully realized for practical applications. This difficulty originates from a fundamental problem: lattice damage induced by ion irradiation reduces the effective concentration of impurity atoms. Nevertheless, the successful realization of ion implantation doping would offer major advantages, including localized doping, process simplification, and self-alignment capability using pre-formed electrodes. This topical review provides a comprehensive overview of boron ion implantation in diamond, tracing its development from early research to the latest advancements. We first examine the foundational work and the persistent challenges that have hindered progress for decades, such as low doping efficiency. The latter part of this review focuses on our recent breakthroughs, which have been designed to systematically overcome these long-standing issues. Our findings in the heavy doping regime (10 19 cm -3 ) have achieved a record-breaking doping efficiency of up to 78% with high Hall mobility. Furthermore, in the light doping regime (10 16 cm -3 ), our detailed analysis has identified a deep donor-like defect, which is likely a boron-vacancy complex specific to ion implantation doping. These findings demonstrate that a multi-faceted approach—combining optimal implantation and annealing conditions, a protective layer, and high-quality substrates—can make ion implantation a practical method for localized diamond doping, paving the way for next-generation diamond power devices.