Sources of n-type conductivity in ZnO

Zinc oxide (ZnO) is a strong candidate for energy-efficient white fighting and numerous optoelectronic applications. Hydrogen impurities play important roles, good and bad, in the pursuit of reliable p-type doping of ZnO. In pervious work, we identified hydrogen donors with the back-bonded or "anti-bonding" orientation, with an angle of 111 degrees to the c-axis. It is possible, however, that these hydrogen donors are complexed with another defect. Impurities besides hydrogen are also donors in as-grown ZnO. Results from secondary ion mass spectroscopy (SIMS) show significant concentrations of Al in samples of bulk single-crystal ZnO obtained from Cermet, Inc., Ga and B in samples from Eagle-Picher, and Si in both. (c) 2007 Elsevier B.V. All rights reserved.