Berlin 2008 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 41: Poster SYM Hydrogen in Materials: New Developments
MM 41.17: Poster
Thursday, February 28, 2008, 18:00–20:00, Poster B
Hydrogen in ZnO - a challenge to experiments and theory — •Gerhard Brauer1 and Jan Kuriplach2 — 1Forschungszentrum Dresden-Rossendorf e.V., Dresden, Germany — 2Charles University, Prague, Czech Republic
Positron lifetime spectroscopy, nuclear reaction analysis and X-ray diffraction have been combined to investigate various, nominally undoped, ZnO single crystals. Hydrogen is detected in all crystals in a bound state (0.3 - 0.8 at.-%), and in some cases also in an unbound state (0.7 * 1.9 at.-%), which can be removed by annealing. A single positron lifetime of 180-182 ps and 165-167 ps is measured for all hydrothermally and melt grown crystals, respectively. These lifetimes are attributed to zinc vacancy-hydrogen complexes, as deduced from ab initio studies of various vacancy-hydrogen defect configurations in ZnO and related positron calculations. In addition, various defect studies of hydrothermally grown (0001) oriented ZnO crystals electrochemically doped with hydrogen are presented. It is demonstrated that a very high amount of hydrogen (up to ~30 at.-%) can be introduced into the crystals by electrochemical doping. It is found that more than half of this amount is chemically bound, i.e. incorporated into the ZnO crystal lattice.