Various defect studies of hydrothermally grown (00•1)-oriented ZnO crystals electrochemically doped with H were presented. The H content in the crystals was determined by nuclear reaction analysis and it was found that already 0.3at%H exists in chemically bound form in the virgin ZnO crystals. A single positron lifetime of 182ps was detected in the virgin crystals and attributed to saturated positron trapping at Zn vacancies surrounded by H atoms. It was demonstrated that a very high amount of H (up to ~30at%) could be introduced into the crystals by electrochemical doping. More than half of this amount was chemically bound, i.e., incorporated into the ZnO crystal lattice. This drastic increase of the H concentration was of marginal impact on the measured positron lifetime, whereas a contribution of positrons annihilated by electrons belonging to O–H bonds formed in the H doped crystal was found in coincidence Doppler broadening spectra. The formation of hexagonal shape pyramids on the surface of the H-doped crystals by optical microscopy was observed.

Defect Studies of ZnO Single Crystals Electrochemically Doped with Hydrogen. Čížek, J., Žaludová, N., Vlach, M., Daniš, S., Kuriplach, J., Procházka, I., Brauer, G., Anwand, W., Grambole, D., Skorupa, W., Gemma, R., Kirchheim, R., Pundt, A.: Journal of Applied Physics, 2008, 103[5], 053508