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The incorporation of hydrogen in n-type diamond has been investigated through its non-intentional introduction during the growth and through post-growth diffusion experiments. In the first case, (111) n-type diamond homoepitaxial films doped with phosphorus have been grown by microwave plasma chemical vapor deposition from a CH4+D2 mixture. The phosphorus concentrations were in the range 1.3×1018–3×1019 cm−3. The concentration of deuterium incorporated is usually 100 times below the phosphorus concentration, which indicates an absence of donor passivation by hydrogen in these films. These D concentrations are well below the H concentration of 1021 cm−3 reported in undoped (111) homoepitaxial diamond films. Exposures of phosphorus-doped and of nitrogen-doped diamonds to deuterium plasma show an absence of deuterium diffusion, even at elevated temperatures (1000 °C). The high migration energy of H−, combined with strong H-donor interactions and self-trapping of hydrogen, are possible reasons for the absence of significant hydrogen diffusion. In natural type Ia diamonds, a hydrogen-related vibrational band is very frequently observed at 3107 cm−1. From the similarity of some properties of this band and of the bands related to well identified (H, impurity) complexes in conventional semiconductors, we propose that (N,H) complexes are responsible for this absorption band. [Copyright &y& Elsevier]

The conversion of the conductivity of B-doped homoepitaxially grown diamond layers from p- to n-type upon deuteration and its reconversion to p-type following annealing is extensively studied. Several B doped samples have been converted to n-type when exposed to a deuterium plasma at approximately 500 °C. The n-type features are related to D uptake of the samples. The donors, thus formed, have an ionization energy of approximately 0.34 eV below the conduction band edge and a high RT (room temperature) mobility (up to 430 cm2/V s), as determined by Hall effect measurements as a function of temperature. In the B-doped layers that do convert to n-type upon deuteration, the D to B concentration ratio is found to be in the range of one to two. Higher D uptake (D to B ratio ≫2) must be connected to B-doped layers containing a large amount of growth defects, which trap the D. The exact nature of the donor is yet unknown. However, the reversibility of the effect and its relationship with the D concentrations suggest that deuterium is involved in the formation of some complex with B or with some other defects. [Copyright &y& Elsevier]