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

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 1015 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 (BETO) intensity to the free exciton (FETO) intensity ratio is evaluated (IBETO/IFETO). A linear relationship between IBETO/IFETO and [B] with a coefficient of 3.5 × 1016 cm− 3 is demonstrated for [B] < 3 × 1017 cm− 3 in single crystalline diamond, irrespective of the gas phase composition during growth.

Research highlights
► Low compensation ratios are got in diamond epitaxial layers doped at 1016 B/cm3.
► Boron dosimetry in single-crystalline diamond can be performed down to 1014 B/cm3.
► Cathodoluminescence at 5 K is the more sensitive tool for boron dosimetry.
► Cathodoluminescence at 5 K is a non-destructive tool for boron dosimetry.