Infrared spectroscopy of hydrogen in ZnO

Zinc oxide (ZnO) is a wide-band gap semiconductor that has attracted tremendous interest for optical, electronic, and mechanical applications. First-principles calculations by [C. G. Van de Walle, Phys. Rev. Lett. 85, 1012 (2000)] have predicted that hydrogen impurities in ZnO are shallow donors. In order to determine the microscopic structure of hydrogen donors, we have used IR spectroscopy to measure local vibrational modes in ZnO annealed in hydrogen gas. An oxygen–hydrogen stretch mode is observed at 3326.3 ${\mathrm{cm}}^{\text{−1}}$ at a temperature of 8 K, in good agreement with the theoretical predictions for hydrogen in an antibonding configuration. The results of this study suggest that hydrogen annealing may be a practical method for controlled $n$ -type doping of ZnO.