Diffusion of hydrogen from a microwave plasma into diamond and its interaction with dopants and defects

The diffusion of hydrogen (deuterium) into various kinds of single crystal diamonds (defect free, boron doped or containing defects) is studied by electrical (Hall effect) and secondary ion mass spectroscopy (SIMS) measurements, Hydrogen is incorporated into the samples from a microwave hydrogen (deuterium) plasma at 820 K. Post-diffusion annealings are also performed, when required, up to 1700 K. The defects are introduced into the diamonds either by ion implantation or unintentionally during the homoepitaxial microwave chemical vapor deposition growth of the diamond layer. The diffusion profile of hydrogen is found to be affected by the presence of dopants and defects (impurities as well as native defects). Hydrogen diffusion is already observed at 850 K in B-doped or defect containing diamonds. This result is in contrast to the case where hydrogen is implanted into a B implantation doped diamond layer in which only a slight diffusion of hydrogen is observed above 1200 K. The electrical characteristics of the initially B doped layer are found deteriorated or improved by the diffusion of hydrogen, depending on the characteristics of the B-doped layer. The experimental results are interpreted in the light of published theoretical predictions. (C) 2002 Elsevier Science B.V. All rights reserved.