Nitrogen and hydrogen in bulk single-crystal ZnO

Zinc oxide (ZnO) is a wide band gap II-VI semiconductor with optical, electronic, and mechanical applications. Nitrogen is a promising acceptor dopant. Nitrogen-hydrogen (N-H) complexes were introduced into ZnO during chemical vapor transport (CVT) growth, using ammonia as a doping source. The N-H bond-stretching mode gives rise to an infrared (IR) absorption peak at 3151 cm-1 at liquid-helium temperatures. Along with passivating acceptors, hydrogen also acts as a shallow donor. In the previous work, we observed an IR peak at 3326 cm-1 that corresponds to a hydrogen donor. It is possible that this donor is actually a Ca-OH complex.