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 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 (BETO) intensity to the free exciton (FETO) intensity ratio is evaluated (I-BETO/I-FETO). A linear relationship between I-BETO/I-FETO and FBI with a coefficient of 3.5 x 10(16) cm(-3) is demonstrated for [B]< 3 x 10(17) cm(-3) in single crystalline diamond, irrespective of the gas phase composition during growth. (C) 2011 Elsevier B.V. All rights reserved.