Study of boron doping in MPCVD grown homoepitaxial diamond layers based on cathodoluminescence spectroscopy, secondary ion mass spectroscopy and capacitance–voltage measurements ☆☆

Abstract Boron incorporation from the gas phase was achieved in MPCVD grown (100)-oriented homoepitaxial diamond layers, either with or without a small fraction of oxygen in the gas phase, in addition to hydrogen, methane and diborane. From secondary Ion Mass Spectroscopy (SIMS), it is shown that the 0.25% of oxygen decreases the Boron concentration [B] by two orders of magnitude. In this way, we demonstrate that it becomes possible to control [B] with low levels of compensation and passivation down to the 10 15  cm − 3 range. Cathodoluminescence spectroscopy is systematically performed in seventeen samples under a 10 kV acceleration voltage at 5 K and the exciton bound to boron (BE TO ) intensity to the free exciton (FE TO ) intensity ratio is evaluated ( I BETO / I FETO ). A linear relationship between I BETO / I FETO and [B] with a coefficient of 3.5 × 10 16  cm − 3 is demonstrated for [B]  17  cm − 3 in single crystalline diamond, irrespective of the gas phase composition during growth.