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Hydrogen diffusion studies were performed in GaN samples with different Fermi level positions. It is shown that, at 350 °C, hydrogen diffusion is quite fast in heavily Mg doped p-type material with the Fermi level close to E[sub v]+0.15 eV, considerably slower in high-resistivity p-GaN(Zn) with the Fermi level E[sub v]+0.9 eV, while for conducting and semi-insulating n-GaN samples with the Fermi level in the upper half of the band gap no measurable hydrogen diffusion could be detected. For these latter samples it is shown that higher diffusion temperature of 500 °C and longer times (50 h) are necessary to incorporate hydrogen to appreciable depth. These findings are in line with previously published theoretical predictions of the dependence of hydrogen interstitials formation in GaN on the Fermi level position. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

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]