Nickel-induced in-situ nitrogen suppression in single crystal diamond: a pathway for high-performance ultraviolet photodetectors

This study proposes a novel strategy to in-situ suppress the nitrogen incorporation during microwave plasma chemical vapor deposition (MPCVD) growth of single-crystal diamond (SCD) through nickel acetate solution bubbling. By systematically optimizing the growth parameters, SCD with nitrogen (<5 ppb) and silicon impurity concentrations below the detection limit of photoluminescence spectrum is achieved. We propose that nitrogen radicals react with nickel species in the plasma to form nickel nitrides, which are subsequently evacuated from the CVD chamber. It demonstrates that a lower dark current and a higher photocurrent are obtained for the metal–semiconductor–metal UV photodetector after nitrogen suppression. The simulation results confirm that the nitrogen-related shallow defect level ( E c  − 0.6 eV) predominantly contributes to the dark current, while deep defect level ( E c  − 2.5 eV) determine the photocurrent. This nickel-mediated nitrogen suppression strategy establishes a pathway for developing high-performance diamond UV photodetectors.