A Systematic Study on Zinc Oxide Materials Containing Group I Metals (Li, Na, K)-Synthesis from Organometallic Precursors, Characterization, and Properties

The reproducible preparation of p-type ZnO represents an important task that might be realized via the partial substitution of Zn2+ by Li+ in the ZnO lattice. Consequently, it is necessary to understand the effect of Li incorporation into ZnO in detail. A systematic approach employing molecular organometallic precursors for the preparation of ZnO materials containing different amounts of Li is presented. The materials have been characterized with various analytical techniques including X-ray absorption, micro-Raman, and low-temperature photoluminescence spectroscopy: high-resolution transmission electron microscopy; powder X-ray diffraction, and electron paramagnetic resonance. It could be seen that Li incorporation is successful only below 12% Li. Already at similar to 1% Li, a maximum in lattice substitution seems to be reached. At higher Li contents, more and more interstitial sites become occupied.